How quickly can the body restore energy reserves mid-ride/post-bonk, and how do we optimise this? I'm interested in how we can maximise restoring energy stores (mainly glycogen, but I'm deliberately being vague) either between closely spaced rides or on long rides.

I ask in the context of a couple of tough rides at the weekend: Friday 277 km solo into a serious headwind, Sunday 324 km with a group (they were all stronger than me and some of them were better rested; we had a bit of a headwind at times but not severe).  In between was a rest day, and a well-fed one at that.

I got to a stage on Sunday's ride where I was clearly running on pretty much  empty: even gentle climbs were almost impossible, and a snack of 100–200 kcal of mostly carbs would perk me up for a few minutes, starting a few minutes after I ate it but then it would wear off.  A meal of several hundred kcal (again lots of carbs) with a bit of sitting around had a similar effect but lasted a little longer.  I'd obviously overdone it: still depleted from Friday ride, trying to keep up with a fast group in the morning and missing a planned stop due to torrential rain, and nowhere open to have a food break out of the weather.  This also meant I ran out of pocket snacks (at least those compatible with rain gear) towards the end and had to stop to get food out of a pannier.

There's literature on refilling glycogen stores over a period of several hours (example paper) but not much about shorter timescales, and how do we translate this to a post-bonk situation when you need to carry on against the clock?  Is it better to have a long break, (perhaps eat, rest, eat again, go), or is it better to try to keep stuffing the carbs in while going along slowly?  Is there a difference if there's a known hilly stretch?

This is related to my old question Fuelling multi-day riding (carb loading/replacement) but this time I'm thinking of what to do when reserves are gone mid-ride – the multi-day aspect of last weekend is more like background, so this is about a much faster timescale.

I'm interested in how we can maximise restoring energy stores (mainly glycogen, but I'm deliberately being vague) either between closely spaced rides or on long rides.

On a ride

Here your ability to actually rebuild glycogen stores are compromised as your body is trying to fuel the activity not rebuild your stores.

Exercise actually alters your physiology, for example the blood flow to the gut is restricted. As such, severe or exhaustive exercise actually inhibits gastric emptying and interferes with gastrointestinal absorption. This makes it difficult to absorb food, why easily digestible  foods such as gels were invented.

Your insulin response is also greatly reduced during exercise as your body is trying to keep your blood sugars elevated so it can create high energy molecules (e.g., ATP) through glycolysis which in-turn are used to power your muscle contractions.

As long as you continue to exercise your body will prioritize creating energy over rebuilding stores, so rebuilding or recovering from a bonk while riding will always be severely compromised. The short answer is on a ride DO NOT let your glycogen stores get depleted. The general rule of thumb is eat something easily digestible carbohydrates at least every 45 minutes. The idea is you want use ingested carbohydrates to elevate blood glucose levels, rather than relying on your glycogen stores, which can be depleted relatively quickly (e.g., within 2 hours)

In-between Rides

Here refueling within the first 4 hours post-ride can be critical:

  Finally, take advantage of the glycogen repletion window that facilitates muscle glycogen repletion in the 4 hours immediately following vigorous exercise. During this time, any carbohydrates you eat are converted into muscle glycogen at up to 3 times the normal rate. And this window of opportunity closes fairly quickly as some data suggests there is a 50% fall in this super charged repletion rate by 2 hours with a return to the normal repletion rate by 4 hours post exercise. (Ivy JL et al,J Appl Physiol 1988 Apr;64(4):1480-5).

  [...]

  After this initial 4 hours surge, muscle glycogen stores are replenished at a rate of approximately 5% per hour. And while it may require up to 48 hours for complete muscle glycogen replacement following a 2 hour ride, for all practical purposes glycogen stores are almost completely rebuilt in the first 24 hours post event.

  [...]

  The rate of glycogen repletion is highest in the first 2 hours and then begins to fall off.
  Is more better? Although the rate of CHO incorporation into muscle glycogen storage begins to fall at 2 hours, there is a maximum repletion rate in the range of 1.5 grams of CHO per kg body weight during the first 2 hours post exercise. Thus a strategy of taking all your CHO replacement in the first few hours is not going to work.

  http://www.cptips.com/recvry.htm

Summary

There are physical limitations to how fast we can rebuild stores. The optimal strategy is not to let your glycogen stores get depleted if you are planning on completing back-to-back endurance bouts.

A lot of this comes down to strategies:

Nutrition, before, during and after;
Not digging too deep on earlier rides, or too early in the final ride (i.e., pacing);
Minimizing your effort where ever possible:

Skipping pulls in the group;
Never letting gaps form between you and your daft; and
Not running a pannier (these are essentially parachutes), instead try a frame bag or a larger saddle bag, as the latter has very little drag.


Crank Set Quality Differentiators I work for a bicycle tour operator in Cambodia. We run daily tours on mostly paved roads. I'm looking to purchase new crank sets for ten bikes but I'm having trouble determining if any of the models are worth additional investment. We don't care about weight, just durability. The tour route is essentially flat. We have a tight budget so I don't want to invest additional money if it's not going to pay off over time.

The specific options I'm considering are Shimano FC-M171, FC-M371 and FC-M361 for $17, $30 and $40, respectively. What should I take into consideration when deciding which ones to buy?

Shopping advice and product recommendations are specifically off-topic here.

However, general advice:

Shimano makes products in a deliberate hierarchy of incrementally improving features, weight and quality. The feature you probably want is removable chainrings, so when those wear out you don't have to replace the whole crank.

The FC-M361 is from a higher product line (Acera) than the other two and has that feature (you can see the chainring bolts in pictures online) the other two do not appear to have it.


Is a 51cm frame road bike the correct size for someone almost 6ft? Looking for some advice on my first road bike.

I've had my eye on a Carerra Virtuoso for about 6 months now, they haven't budged from £350, however I've just spotted one on ebay second hand.

None of my local stores have this bike in stock, otherwise I'd go sit on it to size it up.

Being 5'11" (about 180cm) and 194 lbs, would I be too big/small for this bike?

I currently have a 22" Carerra Kraken and that feels about right size wise

Also, bearing in mind they are £350 new from halfords (and I have £50 halfords vouchers..), how much would be a reasonable bid?

From the website:

  Large bottom bracket to top tube = 51cm which is equivalent to our standard 58cm frame

51cm sounds too small for you; 58cm might be ok or it could be too big.  But there is no substitute for actually trying out the bike, or at least something similar to it.  Your leg, arm and torso lengths all have an effect on how well any bike will fit you and it's based on more than just the seat tube length.

Remember that a bike that's comfortable and fits you well will be more fun to ride.  Good fit is more important than weight or colour -- or even price -- so choose wisely.


Can I upgrade my Specialized Epic Comp 29er 2x10 to a 1x11? I have a 2016 Specialized Epic comp 29er mountain bike that has a 2x10 drive train. I’d like to upgrade to a 1x11 (instead of a 1x10 wide ratio) drivetrain to drop the front derailer and also make room for an internal dropper post routing.

I see complete kits for both SRAM or Shimano with what appear to be all the parts:
crankset and single cog for the front
New 11 gear cassette
New rear derailer
New gear changing switch + cable
new chain

I’m nervous to drop the coin on a new set to find out it won’t fit? how do I know:
1) if my Specialized hi Lo hub is big enough to receive the 11 gear cassette?
2) that my frame is the right size to fit this?
3) is there something else I haven considered?

Yes, it can be done, but you should consider what the cost of the components and  tools or paying for installation would be vs a whole new bike.

You will indeed need a new crank, cassette, rear shifter and chain. May as well replace cables and housings at the same time.

If you have and will stay with Shimano, you might be able re-use the rear derailleur, as Shimano MTB 10 and 11 speeds use the same cable pull ratio, I believe. You just need to check that the derailleur can accommodate the largest sprocket size you will be using.

Unlike road systems, 11 speed MTB cassettes fit on 10 speed wheel freehubs as the largest sprockets can overhang the drive side flange and sprockets a little.


Which threaded fasteners on a bike should not be lubricated? I have the habit of lubricating most screws on a bike with whatever grease I have laying around, except those which aren't meant to be tightened completely, there I use threadlocker (for example the screw holding the brake lever on a canti brake lever set because it would make it compress to the point the lever gets squeezed and can't proerly be pulled anymore). I put some grease on the thread and sometimes on the bottom of the bolt head as well. Also other parts which might move/need loosening (e.g. inside of stem, seat clamp, seat post, cranks, ...) get some greasy treatment. I do this since I've had major problems in the past loosening screws and parts of all kinds, especially drivetrain related, presumable because when not greased water can get in and form rust etc making the two threads stick together. Or maybe different types of material tend to form a bond, not sure. And because in my head I have the idea that when there's less friction one can actually tighten a screw better. And because I assume it can avoid creaking sounds.

Does this make sense? (bonus question: I mostly use generic ball bearing grease for everything, would there be something more appropriate for things which get fastened?). I don't recall ever having problems with things coming loose due to this practice, but are there any screws or parts which should definitely not be lubricated and why?

Basically every metal-in-metal thread on a bike should get some kind of treatment, because at the very least none of them are perfectly corrosion resistant, and as you say, thread lubrication helps with tightening. What it really does is greatly reduce all the many factors that create friction in threads, usually into the negligible range, so that a given amount of torque applied to the fastener gives a more controlled amount of thread preload.

Most manufacturers say to install plastic bottom bracket cups dry.

Many have observed that over time, medium Loctite does a better job preventing loosening on M5 rack and fender bolts than grease.

Disc caliper and adapter mounting bolts are usually Loctited, or left with their pre-applied threadlocker. Probably the big reason is to ward off grease contamination.

Cantilever brake mounting bolts on brakes without an integral pivot are kind of an oddball, because tightening them in the 8-10 Nm or thereabouts range that applies to most other M6 bolts can result in the tip of the boss getting deformed. They should have medium threadlocker applied to the internal thread and then be very lightly torqued, around 3Nm. Because of the low torque, there's little thread preload and grease may make it loosen. But only plain pivot types - brakes with integral pivots, where the bolt shoulder or washer is contacting the brake and not the post, need a more normal amount of torque.

It's good to use anti seize instead of grease on all titanium threads, to prevent thread galling and seizing. I also use it on track cogs and singlespeed freewheels, because it helps ensure they can come off easily again after a hard life of constant torque. You can use it in a pinch on any thread you want to lubricate, the downside being it's messy.

Bearing grease is the normal practice for all threads on a bike you want to lubricate, because it's cheap, does the job well, and you need it anyway.


What does FSR stand for in mountain bikes? What does FSR stand for in mountain bikes?

Ref: http://www.bergwerk.ch/archives/3726/specialized-enduro-comp-2013/

FSR is the name of a suspension design from Specialized. According to a FAQ, it originally stood for "Future Shock Rear". The Specialized website contains an FSR Suspension page with marketing information about the system.


Sleep or not to sleep I am planning to have a tour 230km with roady bike, elevation <600m overall.
I think with average speed will be ~20-25 kmh
What you recommend should I sleep on half of ride? Are you talking about sleeping or just have a 1 hour break?
Problem is if I will start 7a.m I need min, 14 hour to finish. I don't want to ride  at night.
Please share your recommendations.

Note: I have SPD-SL pedals, and all other dress code :)

If you can maintain 20-25km/h riding speed over 230km, that's 9-12 hours of riding time. If your stops are efficient, you can easily achieve that in daylight hours in summer. I still recommend you take lights to be seen by at dusk, and in case you're delayed by a mechanical. You're not likely to be riding for long enough to be sleepy at the half way (or better, 2/3) point. If the distance is much longer than you're used to, your speed will decline and your need for rest will increase. You may then have to stop if you don't want to ride in the dark. Aiming to stop for around 20 minutes every 3 hours, and extending one stop for a proper meal is a fairly typical approach, though many would stop less or more briefly.

You use the word "tour". If that means more luggage than you're used to, then you should probably reduce your speed estimate a little, though your ride is essentially flat, to take account of extra drag.

200km in (max) 14 hours including stops is randoneuring (audax) pace, and the pace is very doable of the distance is. Example :My first 200km (230km including getting there and back) was well under that, despite being a winter ride (always slower).


Cracks in paint on aluminum frame I noticed some small cracks in the paint on my aluminum frame bike. The cracks are clustered around the rear brake boss, and only on one side (NDS). The bike is from 2011 and has been ridden over 10,000 km. Just wondering if it's just cosmetic or something I should be worried about.

I believe the cracks are just in the paint, not the alloy.

Only the white paint is cracked, not the black, the cracks are evenly spaced and run in all directions rather than the single direction a stress crack would follow.


Sound coming from back wheel After the crash I straightened back wheel, and cleaned and lubricated the chain, but now spinning the wheel causes sound as if there is something wrong with bearings.
Here is the video: https://streamable.com/fhb81d.
My bicycle model is Trek Domane AL2. What might be wrong with the bicycle? Should I try to disassemble the bearings and regrease them?
Not holding qr spindle spinning the unmounted wheel in the air: https://streamable.com/gnew8e
Holding qr spindle and putting wheel on a glass table which amplifies the sound: https://streamable.com/keu4xj
Holding qr spindle and holding wheel in the air: https://streamable.com/keu4xj
QR skewer removed and holding the wheel in the air:
https://streamable.com/42vtit
Edit 1
Went to bicycle shop. Confirmed that degreaser got into the bearings.

If the wheel was impacted enough to require truing it’s plausible the hub was damaged. The axle might have been bent, bearings damaged or the freehub mechanism.
You can easily check for bearing problems. Take the wheel out, turn the axle manually. Feel for play or roughness in the bearings as the axle turns.
Hold the axle ends and spin the wheel, check for clicking or grinding noises. Hold the cassette and spin the wheel backwards, check for clicking coming from the freehub mechanism.
The nuts on the axle indicate you may have a cup and cone style hub which can be disassembled. I’d hesitate to disassemble a rear hub though as the bearing arrangements can be complicated.


Keep getting flat with road bike tires I keep getting punctures with road bike tires riding the street in Baltimore. I know they are not the cleanest but I should not be getting a flat every single time. Using Continental Gator Skin and Continental 28mm tubes on my Trek hybrid, which I converted to dropbars to make as many improvements without blowing the bank on a road bike.
I typically keep the PSI around 80-90. These are new tubes and tires as I thought the first flat was related to having tubes and tires that hadn't been replaced in 5 years. However, that was not the issue. I was able to identify one cause being a 3-4mm glass shard that punctured the tire and tube. This most recent puncture shows no sign of puncture on the tire for a very tiny circular puncture on the tube.
Can anyone suggest a couple reasons why I would be consistently getting flats other than road conditions?
Should I consider getting some commuter tires instead?

First thing to check for is sharp foreign objects embedded in the tire that poke through to the inside. These can be small enough or not protrude enough to be invisible, but can poke a small hole in the tube over time.
As this has become a chronic problem I'd thoroughly inspect the insides of your tires. Remove tires from the rims and turn them inside out. Use bright light and run your fingertips along the interior surface feeling for small sharp objects in the rubber. Run your fingers both directions to catch objects embedded at an angle.


What difference does bike size make? I am 6.2 feet tall, and I have a mountain bike that is 17 inches long.
I know it looks bit small for me, but will I hurt myself by riding this bicycle? What should be the preferred bicycle length for someone my height?

That does seem small for your height. Are you hunched over while riding? Does your leg stay fairly bent all the way through your pedal stroke? Are you comfortable after riding for a few hours?

The preferred bicycle size depends on more than just your height, and is best figured out by going into a bike shop, getting some help from the staff, and trying out a few bikes.

Ideally: You want to have the seat up high enough that at the bottom of your pedal stroke, your leg is just slightly bent, similar to how your leg naturally works when you walk. You want to be able to bend forward at the waist a comfortable amount that you could hold for hours, put your hands forward into a natural-feeling position, and have the handlebars right there. You don't want to have to 'reach' for the pedals. You don't want to have your knees bent too much. You don't want to be hunched over. You don't want to be stretched out. You don't want to be leaning on the handlebars. You want to be comfortable.

It's not just your height that affects what size bike you want. It's how long your legs are, how long your torso is, how long your arms are, how flexible you are, and how much core strength you have.

2 people that are both 6'2" may have very different proportions (long legs with short torso, short legs with long torso, or anything in between) have different sizing needs.

Generally, bike size affects both how long the bike is (from headset to where the seatpost goes), and how tall the bike is (from pedals to where the seatpost goes). Both go together.

There are 3 contact points: pedals, saddle and handlebars. You can't really move the pedals, except to get slightly different length crankarms. However, you can get a longer seatpost, seatposts with different amount of setback, and you can move the saddle around a fair bit. You can also get different stems and different handlebars to move the handlebars around quite a bit. All that means that for a bicycle that's only a couple sizes too small, you can probably still adjust it to give you a reasonable fit.

With an MTB that's ridden off-road, you may want a frame that's a touch small, so that when you fall with the bike between your legs, your feet can hit the ground well before your crotch hits the top tube.

In other words: can you get the fit right on this bike? If it feels good to ride for hours and doesn't give you any pain, it's probably fine...


Do you change from cycling clothes when out and about OK, fairly new to cycling, and looking at getting some cycling clothes. Question is do you change into different clothes if, for example you go in for a meal during a days cycling?

Just a matter of priorities, really. If I'm riding out to a meal, then I'll wear clothing appropriate for the meal, and choose my bike accordingly.

However if I'm out on a day's ride, I'll dress appropriate for the ride and a spare set of clothes just represents bulk. Do I really want to carry that extra weight? No way.

Third scenario, if I am away on a multi-day cycling trip, I will wear cycling gear for the day's riding, but will have a shirt and some trousers for the evening. These have to be as light as possible, as again they represent bulk in my pannier. I suppose I could get away with eating in the hotel in my lycra, it's just possibly a bit whiffy for other diners!


Need to know what bike I have the serial # is LP9 0246 badge # is 0589 I believe I have a 1978 Schwinn cruiser the serial number is on the bottom of the Frame and it reads just like this LP9 0246 and the badge number is 0589 can someone tell me what I have?

That serial number is consistent with a Schwinn frame produced in Chicago in November 1978. The numbers on the headbadge refer to the 58th day of 1979, which presumably was when the full bike was assembled, so it was probably a 1979 model.
You can find old Schwinn catalogs online at Bikehistory.org, so I suggest you look through the 1979 catalog and see if your bike matches any models there.


How can I ride a bike having severe spinal disease and pain? I am 27 years old and bound to a power chair due to severe back pain and spinal disease. I have had multiple surgeries and will soon have more. I would like to be active but I know that is nearly impossible due to me being bound to a power chair and the inability to walk except for around the house without a cane. Is there a way or a special bicycle that is made that I can ride a bike??? Please help! I'm dying to get out more without my chair!

I would think some sort of a tricycle would be the best choice for you, probably a recumbent.

Something like this is the first thing that comes to mind:

You lay in a reclined position and pedal with your feet in front of you.  These come in several variants, from fully reclined (such as the above) to more upright.

There are also numerous variations of the hand-powered cycle, and some that are operated with both hands and feet such as this one:

Some of these are "stock", while others are fairly highly customized "one-off" bikes.  (But several versions of the basic tricycle recumbent are available "off the shelf" at relatively reasonable prices.)

I never seen any of these bike styles with an auxiliary motor, but I'm sure there are some.  Several battery-assist systems are available for standard bikes and could be easily adapted to a recumbent.  A full-power gasoline engine would be a bit more complicated.


Electronic shifting for planetary gear hub Gear hubs are nice, but after getting a Rohloff I realized that shifting is extremely difficult and requires lots of effort. So this got me thinking: do electronic shifting systems exist for gear hubs? I know about Di2 for derailleurs, but what about geared hubs?

Rohloff has developed electronic shifting for their hub; Shimano offers an electronic-shifting add-on for Alfine. I'm not aware of any such from SRAM or Sturmey-Archer.


Best type of headphones while riding I'm starting to commute on my bike soon and was looking for suggestions or advice on what type of headphones I should use to listen to music while riding?

I am aware of the dangers of listening to music while riding and intend to only ever have one earpiece in at a time (so thinking in ear / over ear headphones).

I'd imagine that headphones that just "fit" into the ear (Example) would fall straight out. Those that go deeper into the ear (Example) wouldn't fall out but would also reduce outer sound (bad?).

So with this in mind I believe the best choice for cycling would be those that go over the ear (Example)

Am I right in thinking this? Is there anything else I should be considering when choosing a pair?

Many thanks.

N.B. All links are from Play.Com (UK) and are just the first examples of each I found.

I'm not sure there's a best type for cycling, but the latter two examples have their pros and cons and I think you pretty much nailed them.

The last type you posted is going to give you a good snug fit but without the noise isolation of the in ear type (2nd example) which isn't great for listening to music given the wind noise, but for safety reasons is preferable. So if you're riding on public roads and safety is your primary concern, go with the earbud style with the around the ear clip (last example). If you're more concerned about blocking out wind noise and listening to your music the in ear (second example) is the way to go.


6 speed derailleur works for 7 speed cog? I am confused with description it say 6 speed, but below mention 7 speed as well.
Will this derailleur work on 7 speed freewheel?

Shimano derailleurs marketed as 7, 8, 9 speed (and in addition, 10 speed road), can be interchanged in any of those speed drivetrains. Six speed is included in there as well, it's just not common to see. So yes, a six speed rear derailleur will work correctly with 7, 8 or 9 rear speed systems. The derailleurs in these speed groups will all move the same amount based on the amount of cable pulled by the shifter. A limitation of the derailleur can be the size of smallest and largest rear cogs it can handle.  So you might put a six speed derailleur in a 9 speed drivetrain with an 11-34 tooth cassette, and it may shift in the middle of the cassette just fine but will not be able to get the chain on the extreme cogs because it's not designed to handle such extremes which don't exist in a 6 speed system.  So, it's not totally correct to say, ya you can use any of these derailleurs in any of these speed drivetrains because other considerations are necessary to address.
In general, a 6 speed derailleur CAN work in 7 speed drivetrain.


Shimano SIS rear hub offset question I'm a beginner bike mechanic and am working on a used project bike I got cheap. I was just switching out the rear tire and tube for some new 700x25c Gatorskins and when I went to go put the wheel back, I found a really perplexing issue that I hadn't noticed. Namely, the derailleur side of the rear hub had this very strange offset to it, while the opposite hub had no offset.
When I went to put the wheel back on, I struggled with putting the derailleur side hub in, and with getting the right alignment on the non-offset hub.
This is the first time I've encountered this type of derailleur and I'm not sure what to do. Is it possible to get an offset of the same length, on the other side? Any advice?

Yes that's normal for an 80s style bike.  Notice the rear of the dropout slot goes back the same distance, but the drive side has the derailleur hanger there.
You can fit a block in the non-drive side, but having the slot open allows adjustment both ways.  Getting the rear wheel aligned right can be easier if you clamp on the rear brake while doing up the axle nuts, and holding the wheel in the middle of the chainstays while doing the nut up with your third hand.


The name of my frame Can you tell me what the name of this frame is?
The handle is Philips.

It's probably a Phillips brand English roadster. The lugs on this example do not match the picture, but the strange looking rear fork and BSA bottom bracket are typical on English 3 speeds.


What is the difference between MX goggles and mountain bike goggles? After my last ride I have decided that I need to get some goggles, and there seem to be some MX and some mountain bike specific ones, but they seem to be the same. The only difference being that MX goggles are cheaper.

Does anybody know what the difference is between MX and mountain bike goggles? (I ride in wet muddy conditions if that's important.)

Thanks.

Mountain bike specific goggles have less foam padding around the top and are generally lighter. Also the lenses seem to be more flexible but that might just be my imagination.

Cheers


Will increased weight make me go downhill faster? I have had this question for a while. I want to know how I can get down a hill as fast as I can. So, I was wondering if increasing the weight of a bike increases the speed on downhill stretches, or will it just slow me down because of rolling resistance, drag or other factors?

I am talking long stretches here, and long, 10-30% hills. I have also checked the road surface, and there are no bends, and I can easily see if traffic comes along. It is very rarely used for traffic anyway.

Thanks

EDIT: I would also like to factor in things like rolling resistance in this question.

The main thing you have to consider at speed is drag:
The force F on you+bike (mass m) is:

F = ma = mg sin Q - F_d - F_rr

where a is your acceleration, g is the acceleration due to gravity and Q is the hill angle to the horizontal. F_d is the drag force which doesn't scale with mass. Try dropping a balloon and a (soccer) football of the same size and you'll see this in action. F_rr is the rolling resistance.

Drag dominates rolling resistance at any decent speed for a well-set-up bike: More detail than you probably want or a nice graph so you should be able to neglect rolling resistance.

Weight will have a small effect on rolling resistance and (assuming it doesn't affect the cross-section) none on drag so it will make you accelerate faster but not by much.

You might want to experiment: start with some measured speeds with no extra load, then test the extra mass, and a dummy load of the same volume/shape/mounting made of polystyrene or cardboard.

The biggest effect you'll have is on the drag - so the first thing to try is a better tuck, not wearing flappy clothes, etc.

For really high speeds a fairing is the way to go - compare the hour record for a fully faired recumbant (~92km) with a UCI racing bike (~52km).  There are no stats I can find specifically for an upright with a fairing.


timing chain keeps dropping/derailing only with partner For a volunteer project biking with blind riders (NiewidomiNatandemach.pl), we've been partnered up and provided a tandem bike, that seems new enough and in good condition.

Unlike the guy behind me--about my same weight and pedaling strength--as the pilot in front I get to see the upcoming terrain and decide to gradually steer or shift gears (5-speed) before it is "felt" and becomes tactily intuitive.

I can't quite figure out why the timing chain(front) keeps dropping out of its front chainring, jamming to the right, between the teeth and disk separating the pedal. Almost always we have to come to a full stop and re-seat it by hand.

There is a sprocket 10-teeth wheel supporting the lower part of that chain, pulling it upwards. I had adjusted it higher & lower to test various tensions; often it too easily loses the chain.

The top part of that chain is nearly a straight line with little to no drooping. The whole configuration is thus (actual bike photo now...evidently wasn't clear enough that previous was just smth similar from Google Images):

Some findings:

No matter how much I try to "aggravate" it with sharp turning, gear-shifting, breaking, etc., I cannot get it to derail when riding alone. Then it works fine.  No slipping nor skipping either.
Our latest working theory vaguely points to situations when the rear rider is momentarily applying more pedaling torque than the front. Unfortunately these are inevitable and unforeseen, as much as we try to communicate and coordinate maneuvers. (Comment response: yes, we thoroughly talk or otherwise signal while biking. Again, there are situations despite this when the pilot has to make unplanned but instant judgement calls for our safety, though these are not dramatic nor unusual for the bike itself.)
Yet the rear chain never slips off, even though that's the only place gear shifting happens: at the rear wheel only. There is no left-handed gear shift.

Any ideas?

Other things tried that didn't seem to change much:

Switching to an 11-tooth sprocket
Bypassing the sprocket entirely by removing 4 links in the front chain

Local mechanics & standard bike shops in our small town happily mucked with it, but don't appear to know exactly and be able to remedy.

EPILOG

This band-aid at least kept us going pretty well the whole week:

The strings/cables suspending the sprocket directly upwards added tension to supplement its thick spring/coil.
Again, shortening the chain by even the minimum possible made it already too short to fit.

This answer has been significantly changed since being accepted because the accepted answer cannot be deleted.

Based on the new photo, your timing chain needs checking. Its quite uncommon to see both chains on the right side of the bike, but not impossible.

Do both timing chainrings have the same number of teeth, or do pedals go out of phase over distance ?

Are the chainrings in line? You might need a keeper on the front chainring - essentially a front derailleur mech that doesn't move.

Check for timing chain and chainring wear too - if its worn/elongated then fit a new 1/8" timing chain. Leave it too long and the chainrings will wear out as well.

1/8" chain will last much longer too, and will slip less because it doesn't flex left and right as much as normal 3/32" chain.


Can I install a gears cassette on a regular bike? I was given a bicycle for my birthday (yai!), it has 24" wheels and it is awesome!

But it is single speed and sometimes it is hard to ride up-hill in my daily commute.
Could I change the rear gear for a gears cassette?
If so. Do I need to change the rear wheel as well?

PS. Am I using the correct terms? I'm new using english to talk about bicycles.

Converting your single speed bike to geared one is probably not worth the effort, for several reasons:

Cassettes and hub gears both need different kind of wheel hubs than single speeds. You will need to change the whole wheel.
Single speed bicycles usually have narrower rear fork spacing (distance between rear fork dropouts) than geared ones. Your rear fork might not be wide enough to accommodate any geared hub.
Being single speed, your rear dropout most likely doesn't have hanger for a derailleur. Add in parts, and derailleur than can be mounted on the axle do exists, but it adds extra layer of trouble for the whole enterprise.
The frame of your bike probably doesn't have any cable guides either. You will have to either find add in guides, or use makeshift solutions.

In short, I wouldn't try it. It might not be possible at all, due to rear fork spacing. Even if it is possible, it's going to take money, special tools and quite some time put functional gears on your bike.


How did my rear freewheel become incredibly tight overnight? I got a flat yesterday morning after a normal ride, walked my bike inside the house and propped it upside-down (like this) overnight.  This morning, I changed the flat and put on some brand new tires I bought last week.

When I take it out for a ride, I find that the freewheel is nearly locked up!  I can forcibly move it by dragging on the pedals and bunching-up the chain, but it's not easy.  I've tried adjusting the tension on my quick-release, but that doesn't seem to make a difference.

The freewheel on my SRAM S27 has always been tight (to the point of putting some slack in the chain when back-pedaling), but now I can't even coast!  How did this happen, and what should I do about it?

Edit - the next day:

I made my adjustments on Tuesday morning as I said in the comments, but after only a 15 mile ride the freehub was completely tightened back up again!

After looking into it a bit more carefully, I found a service manual for my wheels with some nice pictures.  Here's what I adjusted on Tuesday morning:

I apparently loosened the "end cap" from the threading on the axle.  Here's another pic of the whole assembly:

Unfortunately because it tightened right back up that obviously wasn't a very robust solution.

I decided to put up another answer because while Daniel's hunch and Billy's excellent answer get at the gist of the solution, I did find some specifics that might help someone else (though perhaps only a SRAM S27 owner).

First of all, the service manual is pretty helpful.

In my case, the "end cap" was tighening on its own during rides.  Normally, this little set screw is supposed to keep the end cap from threading or un-threading (ie. you get the adjustment just right, apply the set screw, and it should all just stay put).

The set screw actually applies pressure to a rubber o-ring, which in turn presses against the threads on the axle to keep the end cap from turning.

On my wheel, that o-ring had actually partially disintegrated where the set screw contacted it.  So instead of pressing a healthy o-ring against the threads, it just sort of mashed some rubber particulate in there.

The right solution to this problem is probably to get a new o-ring.  The route I took, however, was to rotate the o-ring about 90° so the set screw was once again above a healthy bit of rubber.  I then re-adjusted the end cap tension and re-applied the set screw.

Hopefully that keeps me going for a while without tightening up again.  Thanks for all the help, everyone!


Winter tires with removed studs as summer tires? I have just a set of summer tires in very poor condition and a huge heap of studded winter tires. Selling winter tires is very hard so I got an idea to use the winter tires as summer tires with removed studs.

Is it a good idea and how should you remove studs without damaging the tire itself?
Can you use the tire afterwards as winter tire or will the studs become too loose? Any experience?
Should I fill the stud-positions with something if I remove the studs?

The winter tires are W106 Nokian tyres, Hakkapeliitta.

While the tire itself might or might not be intact after removing the studs, the tube inside the tire would suffer. Studs are installed by piercing the tire itself, and you'd have to patch the hole left by each stud or you'd have blowouts.

I suggest selling the extra studded tires.


Damaged Carbon Steerer Tube, repair/replacement? I cracked the top of my 2007 Schwinn 1 1/8 fork black label steerer tube.
What kinds of repair are available? Should I just buy a new name-brand carbon fork, e.g., Canondale, GT, Trek on ebay?

The standard line from the carbon repair shops is they don't do forks because new ones are a lot cheaper. My understanding is that safe steerer repairs are technically possible in a lot of cases, so if you want to go nuts or if the original is unique in some way you might be able to find someone to do it, but it's probably not worth it. I think in practical terms, the real problem is that a lot of the time if one part of a carbon fork is destroyed, the rest might be pretty well-loved also.
The usual approach is to measure the axle-to-crown and offset dimensions of the original and go shopping for something close. Among carbon rim brake road forks, there's not a lot of variance. A number of companies make what are essentially repair forks for this kind of situation.


GPS bike tracking (locks) I have seen a few GPS devices either in the backlight or unside the seat tube which you can track if you lose your bike (your bike gets stolen).

What do you think about this stuff. Is it worth the money and how easy is it to track your bike with this things.

Pain in the ass, and waste of money.

As of the last time I checked, you can't track them directly (there'd be no way for you to receive a signal from a battery-operated device 5mi away), so you need to sign up for a recurring monthly service. On top of that, they chew through battery pretty quickly, requiring a recharge every few days.

Contrast that to just buying a decent set of locks. If you need to lock up your bike in the same place every day, get a thick $80 chain and a cable for the front wheel. If you need something lightweight to carry around you, a $50 u-lock is going to be a reasonable level of protection.

If your bike is worth more than a few grand, you're absolutely crazy to leave it outside at all.


Possible cause for Google Maps / bicycle odometer divergence (tire size setting correct) I have plot my exact route from home to my office using Google Maps. By exact, I mean that I took nearly every turn and change from auto-calculated route to match my exact route into consideration.

Google Maps claims that my route is 10.4 km. Everyday I'm riding it, my bicycle's odometer claims that I have actually traveled 11.11 km.

I did exactly the same with my return route (a bit different) and after including every actual turn, change etc. it turned out that route is 9.5 km according to Google Maps and 10.43 km according to my odometer.

The difference is 0.7 / 11.1 = 6.3% on the outward trip and 0.9 / 10.4 = 8.6% on the return trip1.

My first and of course obvious clue was an incorrect tire size setting in my odometer. However, I double-checked to be sure it's correct:

I have (50-559) 26x1.95 tires, so I believe I should set it to 2089.

What else could cause the difference?

I have consulted this with a very experienced bicycle rider, but he mistakenly thinks it's because the Google Maps route doesn't always match the actual route. However, I spend some time adjusting the auto-calculated route, so it matches my actual route in about 99.5%.

1 Assuming that my difference calculation formula is correct. Plus -- I don't know why divergence is higher in case of return trip. The only clue, that I have is that it takes much more backroads, turns, slow downs (while onward trip is riding on the streets nearly all of time), which causes, that travel time is longer in case of return trip even though it is shorter. But, that is a weak argument as divergence should be the same in both / all cases.

Google maps probably treats roads as not having any width, and corners as point turns. Unlike bends, if you zoom in you tend to see a sharp 90 degree change in line on a curve This will cost you the length of the arc you really take.

It certainly omits all the lane changes, obstacle avoidance and similar manoeuvres.

However there is some variation in tyres - particularly some of the anti-puncture tyres have a bit of extra thickness; inflation vs. weight on the wheel will also have an effect. So you're better off seeing the wheel circumference based on counting the wheel revolutions over an accurately-measured straight line.


Best practice for patching snakebite pinch flats on skinny tubes So, I tend to run 700x23c or 700x25c tires on my commuter bike. Sometimes I'm lazy and forget to check the air pressure and inevitably get a pinch flat when I hit some stationary object, pothole, or big curb.

When I get a snakebike type of pinch flat (2 holes somewhat separated, usually on opposite sides of a ridge in the tube, I find it hard to patch.

Either I use a small patch without having the small patch only extend past the holes 1mm or 2mm and usually placed over the ridge/seam in the tube, or I use a large patch which is really hard to apply since it is wider than the tube (making it hard to apply glue and appropriate pressure to patch when gluing) but provides coverage for both holes at once.

Park tool GP-2 glueless patches seem to work ok for this situation since they can easily be overlapped without issue.  However, I hear anecdotal evidence that they are not as durable as patches used with vulcanizing fluid.

What is the preferred way to patch these type of tricky flats?

Use the thinnest conventional (tube-of-glue type) patches you can find.  They should be the type with feathered edges.  A little overlap is OK, but trim the edges if there will be a lot.
Better still, swap in your spare tube.
Better still, don't let your tires go flat.

(Avoid using large patches as they won't expand as the tube expands.)


What do I need to replace my singlespeed freewheel cog? As I learned in this question, the cog of my freewheel are damaged and should be replaced.

I've been searching for some information but I'm still not sure of what I need. At the beginning I though I just needed to search for a cog like this with 1/8" like my chain:

But reading the description it seems like it's only for fixed gears, so I was completely worng. Searching for more items under the single speed category in the website everything looked like that.

What do I need to buy as replacement?

This is how what I have now:

As tools a I just have the basics, when i search for freewheel remover I see hundreds of different things like this:

 ...

How can I know what I need?

Update with photo of the wheel:

Park tool has a guide to figuring out what type of free hub/freewheel you have, and what tool you need to get it off.

https://www.parktool.com/blog/repair-help/determining-cassette-freewheel-type.

With that knowledge you should be able to to figure out what type of replacement freewheel/spocket you need (or two, as you have a flip-flop hub).

Update:

Also see the Sheldon Brown page on Freewheels.

Depending on what the freewheel thread turns out to be, you should be able to get a replacement freewheel that has a more standard lockring.

You might consider creating a 'bodged' tool to get the current freewheel off. You might be able to 'drift' the lockring loose by tapping the ring around with an old screwdriver and hammer.


Is there a polite way to take the centre of the road without antagonizing motorists? The city I live in isn't especially well designed for cycling.

There are some streets with parallel parking on the sides, and in this situation it's safer to ride in the middle of the lane as to force cars to pull right over to pass, (or wait), rather than trying to squeeze past on the same lane.

However I get the feeling that this antagonises some motorists, even though it is the safest way to ride.

Is there a way to ride safely, while minimising motorist antagonism?

In my experience, no. The problem is that however polite you try to be you're taking the lane so you're in their way.

My commute takes me over a narrow one-lane-each-way bridge that's a bit of a choke point, so it's busy. It's also a raised bridge, so sight lines are very poor. Since I ride it twice a day I've had the chance to experiment with some different approaches. Normally I ride during daylight, so I'm only considering that at the moment, but I have dynamo powered lights that are always on (they don't flash).

1: ride normally, take the lane
Result: most motorists are fine, perhaps 10% follow closer than I'd like (within 3m), occasionally one will (illegally) overtake, often failing to allow the 1m separation that I like, but since I have room I simply move away from them.

2: ride "politely" as close to the side of the road as I can
Result: 5-10% of motorists try to squeeze past me, often pulling back in before they have actually done so and forcing me to brake to avoid being hit. Some of them are aggressively close and these are the only times I've been abused.

3: take the lane, but turn my daylight-bright blinking lights on
Result: very few motorists follow too close, only one overtaking motorist and that was when there was clearly no oncoming traffic (still illegal, but relatively safe)

4: ride on the (narrow) footpath
Result: rather than being scared of misbehaving motorists, I'm now illegally terrorising pedestrians (of whom there are quite a few). I've only done this a couple of times, both because the road was packed with cars and I really didn't feel up to fighting for my place on the road. I don't feel good about it.

5: take the lane, lights on, helmet camera
Result: sore neck, as for (3) above.

I've basically stopped experimenting with this because the results are, in my opinion, conclusive. I turn my lights on when I leave the bike path a couple of hundred metres before the bridge (bright flashing lights on the shared path are, IMO, rude and unnecessary), or when I leave home (the bridge is ~1km from home). So I'm always using the flashing lights when I'm on the road.


Finding a serial # 1952 Schwinn Panther I believe I have a 1952 Schwinn Panther.  Trying to find the serial numbers but very rusty.  Where exactly should I look and will a wire brush help or hurt the bike?

Up until 1952 serial numbers we printed on the Bottom bracket shell, after 1952 they moved them to the rear dropout until 1971 when they were again moved, this time to the head tube beneath the oval badge. Being on the cusp of years i would check both the BB shell and the rear drop out. This information can be found in an informational bulletin released by Schwinn here.

I doubt you will do to much damage with a wire brush, as long as there is not good paint on the frame, which will be scratched from a wire brush. You may also consider using a rust eliminator such as CLR (Calcium Lime and Rust), it could be sprayed on with a spritzer style bottle and rinsed off with alcohol or water. Light brushing along with this may be enough to make out serial numbers.

Once you find it This web site may help you decipher it's model as well as date of production.


Shimano Ultegra 6800 front derailleur tension problem I'm building up a 2015 Salsa Colossal Ti with a full Ultegra 6800 groupset (though with the RS685 hydraulic shifters).  I'm having an issue setting up the front derailleur.  I've followed all the various tutorials online, but whatever I do, I can't seem to get the cable tension right.  Too little tension and I can't get the derailleur to hit the high limit screw.  But when I add the necessary tension, then the derailleur won't hit the low limit screw.  I either have chain rub in the 50/11 or in the 34/32.

I even have the little plastic tool that tells you whether the converter should be on or off (off in my case).  Out of desperation, I've tried the other converter setting, but no luck.

The factory built bike from Salsa comes with the same Ultegra components (apart from the RS685 shifters), so I know I should be able to get this to work.  Am I making some rookie mistake?

The rotational position and height not being exactly right would cause this. Shimano now has a more specific procedure then in the past to establish them, which you can see starting on page 5 of the dealer manual.

If following the procedure in their manual to a T doesn't work, the other thing you may be looking at is a situation such as Lennard Zinn describes in his column on 11-speed Shimano road FD setup where the cable anchor has to be set in an unorthodox position going over the top of the bolt. The dealer manual demonstrates this as a thing you're not supposed to do on the page 14, the two graphics on the right hand side of the chart. It may be worth a try.

As is pointed out further down in that column, problems with these derailers almost always revolve around not having enough cable tension. All aspects of the setup have little if any margin for error and they need as much cable tension as possible. They also need the low limit screw set super close. That  0-0.5mm inner cage clearance number on page 15 of the manual is one that's been around for a while and used to be more or less unrealistic, but they mean business now. It has to be all but touching, and it will work better if it's almost kinda sorta touching (the "0" end of the range). Usually it's the case that if you set it up in the stand for the chain to just barely touch the cage sometimes in the low gear, it won't rub when you're actually climbing because the chain is under so much more tension.


How urgently do I need to replace my tire? When I came home today from by bike ride I found my tire like this:

I understand that I'll need to change my tire. My question is how urgent is this? Can I just keep using the tire until it stops holding air, or is this dangerous, and the it might pop when I'm on the bike?

That’s really bad. Replace that tire immediately, before the next ride for sure.
When you can see the cloth skeleton of the tire, that means it’s finished. The cloth is nowhere near as abrasion resistant as the rubber, and you’ll soon rub through it. When that happens, the tire is likely to fail dramatically in something known as a “blowout”. This is a very sudden event that leads to a high risk of crashing. Don’t tell yourself that you’re skilled enough to ride it out, it’s just not worth the risk.
Furthermore, see how the side of the tire is fuzzy? That means the cloth on the sides is damaged. If it tears, again, your tire might explode and you will likely crash. Do not try to risk it.
Edit: Realize that it is not the tire which holds air. The tire itself is porous. From a pneumatics viewpoint, it only serves as the mechanical device resisting the 70+ psi outwards force from the air. Inside the tire, there is another rubber donut, which is an impermeable bladder known as your “inner tube”. This inner tube is not strong enough to hold that amount of pressure by itself. Henceforth, when you wear through enough of the outer tire, it will fail to be strong enough to resist that 70psi and subsequently tear. The weak inner tube will then expand through the tear and burst because it isn’t being contained by the tire anymore. Although it will become easier to puncture the tube as the tire wears down, it will not give you any major advance warning (you might hear cloth ripping and threads breaking, or you might not. Depends on your luck and the exact cause of tire failure. Hitting something like a sharp rock definitely will not give any warning) before it lets go altogether. Since it is only the inner tube which holds air, the tire will keep on going until it instantly rips apart.
Congratulations for riding so much you’ve worn a tire out though! That’s awesome!


Can I change from short to long derailleur to increase cog size I am have a tiagra 11-25 10 speed cassette with short cage. I am a poor climber and looking for extra gear; I would like to go 11-32 for this year until my climbing improves, will the short cage derailleur take a 32 teeth cog?

If not what 10 speed derailleur is recommended?

It doesn't look like you'd be able to use an 11-32T cassette at all with a 10-speed Tiagra rear derailleur.  From [Shimano's documentation] (http://bike.shimano.com/media/techdocs/content/cycle/SI/SI_5XN0A/SI-5XN0A-001-Eng_v1_m56577569830746860.pdf), the largest sprocket that either the short cage or long cage version supports is 30T.  If you wanted to use their 12-30T tiagra cassette, you would need the long cage because the tooth difference has to be 16 teeth or less for the short cage, whereas the long cage supports a tooth difference up to 22 teeth.

If you really want to go up to 32T and stick with a road derailleur, it looks like you'll have to upgrade to the newer 11 speed stuff and get the long cage version.  The [11 speed Ultegra] (http://bike.shimano.com/content/sac-bike/en/home/road/shifting---braking/rear-derailleurs/rd-6800-gs.html) derailleur looks like the only road derailleur from Shimano that would support an 11-32T cassette.  Incidentally, that's the derailleur that came stock on my 'cross bike and it's got an 11-32T cassette on there.


Will 2 x 10 speed front derailleur work with 11 speed set up? Would an existing 2x10 front mech work with a new 11 speed rear set up? Using all Shimano SLX with 11 speed shifter, rear mech and chain. Front chain rings are 2 x SLX 38/28.

11 and 10 speed cranksets have slightly different chainring spacings to accommodate the difference in 11 and 10 speed chain widths. Front derailleurs have slightly different movement also.

You have a matching 10 speed front derailleur and crankset, so really the question is whether an 11 speed chain will work on a 10 speed front. I think from past answers I have seen here it will work OK.


Massive and sudden increase in heart rate and vomiting after when cycling The heart thing has happened a few times before, and the vomiting only once; but I haven't cycled in about a year and am getting back into it. I used to be a gymnast and did pretty extreme conditioning and never experienced this then; it's only with cycling.

My body doesn't feel fatigued, overall when this happens my muscles, legs etc feel like they could sprint for a mile with no issue. I'm never panting or struggling for breath or anything like that. It's just my heart and a sudden overwhelming sickness.

If you've seen Gattaca; the scene where the main character is on the treadmill with the fake heart monitor and then later collapses in the lockerroom is exactly how I would describe these episodes. In fact watching that scene makes me feel very uneasy and my hands start shaking; because the episodes feel like I'm about to die...it's extremely frightening.

Is this just a matter of endurance? I'm definitely going to talk to my physician next time I go for a check up. I don't eat large meals and I wait at least two hours before I go on a ride, and I don't particularly "go hard", I just kind of cruise. But I live in Seattle and it's pretty hilly here. Normally I just rest, lay down, sit-up, vomit, and I'm good to go. But I would really, REALLY prefer to not experience this ever again.

Advice?

Go to a doctor - this sounds dangerous. Anything you see on SE is not a substitute for professional medical advice and it sounds like you really need to see one.


Look Keo pedal no longer floats. Can it be fixed? I've had look Keo pedals installed on my road bike for a few years. Recently the right pedal has felt like it no longer has any float (potentially seized up?). This is starting to cause me foot pain on longer rides, so very keen to solve it before it leads to injury.
The cleats I'm using are only a few weeks old, so I can't see how it would be those causing it.
My main question is whether there is a way to service pedals to fix this? I know the axles can be serviced quite easily. Otherwise, is my only option to replace the pedals?

I have tried old and new cleats in the pedal and in the other pedal (Which seems to be fine). I use the grey Keo 4.5 degree cleats and always have done.
I've tried putting the left shoe into right pedal and vise versa, and it appears that the problem is pedal specific (Right shoe works in left pedal, left shoe doesn't work in right). I believe it was an issue before the cleat change, the same foot pain existed, but I didn't know the cause. I've checked for for stones/muck, both pedals are clean and clear of debris.
As a follow up question, what are the reasons that would make you change your pedals? Could this be caused by one of those reasons?

Put some soap on the cleat contact points to lubricate it.
Be careful not to get it everywhere, just in case it becomes too floaty!
This assumes you have covered a bunch of other options (of course!)

The cleats are actually the same and you didn't mix-n-match (some other manufacturers make compatible cleats which might be slightly different)
The black protruding insert is not different / damaged / inserted incorrectly.
All the caveats above regarding dirt etc.


Too much movement in the stem Basically what is going on with my bike is that I tried to fix a creaking problem in the area where the stem and the bike frame meet. I took apart the front of the bike and some of the headset pieces came off without me knowing and I don't know how to put them back. Whenever I try to put the pieces back together, the fork tends to still move around.
Description:One picture consists of the original bike and how it looked.

Description: The other image shows how when the front of the bike is lifted, the front wheel moves downward leaving a gap.

Please take your bike to a competent bike mechanic.
We can explain how to properly adjust and maintain a threadless headset. We can also give you hints on how it has to be assembled. However, that you are asking this question shows that you are not at a point where you can fix it so that someone can ride confidently. If the steering, headset, or stem fail a terrible crash is likely to happen.

Assembly
Your bigger appears to have a threadless headset. A headset is the set of bearings that holds the fork in place and allows smooth turning. Since it has to take side loads, forces perpendicular to its plane of rotation, It consists of two angular contact bearings. These need to be pre-loaded.
There is a conical ring with a 45 degree face on the fork crown. The lower cartridge bearing is slid onto the steerer onto it. It should fit closely. The bearing then fits into a cup pressed into the head tube or the head tube directly.
The upper bearing is always rotate by 180 degrees to the lower bearing, so that the angled races take forces along the steering axis opposite to the lower bearings. It slides over the steerer and sits in the head tube, either directly or in a cup. Make sure the 45 degree face of the bearing fits the angled face in its seat.
Next comes a split conical ring. It slides on the steerer and sits on the inside angled face of the bearing. This ring has to be pressed down by the rest of the assembly to pre-load the bearing.
The pre-load is applied through a conical cap, spacers, the stem, (another spacer), the top cap (parts in parentheses are optional).
Most likely there are a number of plastic or rubber rings to seal the bearing assembly.
Adjusting
While adjusting the headset the stem has to be lose. Just close the screws enough so it sits properly on the steerer but can be turned easily.
Tighten the top cap screw. This presses onto the conical ring in the upper bearing via stem and spacers. Here one needs a bit of experience for the correct pre-load. It has to be tight enough to take out any play of the system, and then a little more force. But too much and the bearings will not move smoothly. WIth excessive force the bearings, or their seats will get permanently damaged.
When the top cap is tensioned to the right strain, close the stem bolts. Even when you remove the top cap now, the bearings will keep pre-loaded. It is important that the stem clamp takes all the loads while riding. The top cap is not strong enough and will fail.
Again, get a bike mechanic to fix it. If you botch it, at best you get a bike that doesn't steer, at worst you get a bike that sends its rider to a tumble that breaks their neck.


Is my six-year old touring bike worth repairing? My touring bike (which I use for commuting) needs repairs which will cost £200... half the price of a new one.

I am not mechanically-minded.... and I am too busy and too old to learn!

A new bike will cost twice the price. But with the new bike, I get all the things the repairs will bring.... plus new wheels, new tires, a shiny frame (the current one is scarred but not damaged).

The bike shop say repairing is the best option.

I'm thinking.... keep the bike over the summer.... and buy another when the end-of-season sale comes along.

The repairs are: a major service, replacement of all the drive mechanism, etc.

Advice please!

As LBS mechanic, I also would recommend to repair - the cost is sufficient. Your bike will be almost as new.
So if it's a bike that worth repair (like mikes mentioned), and your tires and derailleurs are in good condition yet, go for it.
If you know that you should replace tires or derailleurs soon, better is to buy a new one with all parts new and a warranty.

Edit: if you will anyway buy a new bike soon, you should consider whether you want to do all this repair, or a part of it will be enough.


Missing lock nut part on Dura Ace WH-7900 wheels Not sure what to call it, but a couple of my wheels are missing the grippy washer thing that sits on the lock nut. They seem to be attached to the lock nut to begin with, but they just fall off after a while and get lost when swapping wheels.

Can they be replaced?  If so, where can I find the replacement part?

With:

Without:

It looks like the washer in your photo may be a "Wedge-Lock" washer like those available here: http://www.mcmaster.com/#standard-washers/=xhptlp

They appear to sell under the names "Heico-Lock" & "Nord-Lock".
This may be a UK source: http://uk.rs-online.com/web/c/fasteners-fixings/nuts-washers/locking-anti-vibration-washers/

I should note that there very well may be a similar looking shimano specific part that functions differently & that I am not familiar with. I'm basing this suggestion solely on appearances.

If someone knows that these are in fact not the same as the item pictured by the OP, please enlighten me!

EDIT: To add further to possible resources, at the bottom of this page: http://www.heico-lock.co.uk/products.html There is a list of "Wedge Lock Nuts & Wheel Nuts" (Nuts with an integrated washer half). I do not see any resale links though...


Old bike - what can I use for crank replacement? The LBS doesn't have anything in stock to replace the crank on this bike :

What is this type of crank and does anyone still supply them?

It's hard to tell from the picture, but it looks like a cottered crank. I don't think anybody makes them anymore, but not all hope is lost. You can likely replace the entire crankset and bottom bracket assuming the bike has a bottom bracket which is still available, which is somewhat likely. It may cost more than you are willing to spend on the old bike though.


Can broken caliper be fixed? I have a broken hydraulic caliper and am wondering if it can be fixed? Can I buy the half that the broken mount is on or would it be better just to buy a new one?

I highly doubt you'll be able to find a separate alloy casting to replace the one that broke. Even if you can you'll be faced with assembling the caliper which is not trivial.
Just buy a replacement caliper. Make sure you refill/bleed the hydraulic fluid according to Shimano's documented procedure, of have a competent bike shop do it for you.


What threads are used on Avid BB5 barrel adjusters? I thought I might replace the locknut on my front brake barrel adjuster because the current knurled one needs pliers where it sits in an awkward place behind the mudguard stays.  But it's an unusual thread.  It's bigger than M6, but it's 1mm pitch (or 25tpi) An M6 screw seems to engage the female thread but pulls straight out.
Their in-line barrel adjuster uses M6 threads, and I could fit one of those when I re-cable anyway, locking off the one on the brake - but I don't plan on replacing the cables just yet.

They did indeed turn out to be M7 (1 mm pitch).
Nuts are fairly easy to get, but at least the locknuts (half nuts) I bought take an 11 mm spanner.   None of my multitools, or any I can find online, have this size spanner built in; even my workshop spanner set omits it, but in over 20 years of building and maintaining hardware for work and play, this is probably the first time I've handled M7 parts.


Which size inner tubes to buy? New to cycling and have no idea what size inner tubes to buy for my particular bike.

Following dimensions on tire:

  N28x1.75*36H

  622*19c

Seems to me this is an unconventional wheel size? Was on Wiggle and most tubes seem to be 700x25c.

The 622 x 19 is the rim size. 622 refers to an ISO 622 (700c or 29" in mountain bike parlance) wheel. 19 refers to the rim width in millimeters.

The 28x1.75 is 700c x 45 tire size (or equivalently a 29 x 1.75). So, you need a tube suitable for this size. Tubes are sold by ranges, but it's not hard to find a 700c x 28-47c tube (this is what Schwalbe sells). You can also use tubes marked 29" x (some range containing 1.75). If you go to a bike shop and ask for either a 700c x 45 or 29x 1.75 tube, they should have you sorted out in a few seconds.

The 700c = 29" thing is usually 700c for road/hybrids, 29" for mountain bikes but its the same wheel size. Confusingly, another name for 700c is 28". Why? Aliens.

As Criggie points out in the comments, make sure your tube has the right kind of valve. You could take your old tube to a shop and they'll sort you out. Or the bike.


Can I change the rear cassette on a folding bike? I currently have a folding bike (think Dahon like) with 20" wheels and a front chainring of 52T and a rear cassette of 14-24T. Although 14 provides me with good speed I'd love to get faster speed for less spinning. I found a 7 speed cassette that is 11t-28t (Shimano HG30-7 which is 11t,13t,15t,18t,21t,24t,28t) and wondering if just switching the cassette would work or if I'd also need to switch out the rear derailleur as well (I think it is a Shimano TZ-21) and potentially also the chain (longer?)?

I can't say for sure, but you have a decent chance of being able to just adjust the body screw on the derailleur to increase its clearance for the larger cassette (see "B-screw Adjustment" on this page).

As you've also noted, the chain will be tighter when in that lower rear gear, which might work but more likely than not you're going to have some difficulty shifting into low rear gear and/or front big chainring without making the chain longer. You can potentially just splice in another link or three (most LBSs will give them out for free, although make sure you know what type of chain you have -- probably standard seven speed) rather than purchasing a whole new chain.


Is it legal for me to ride a bicycle on the pavement (sidewalk)? UK only, just wanted to check if it's actually legal. The area I'm living on is deadly on the roads, so want to know about riding on pavements (sidewalk/pedestrian walkways) instead where there is no bike lane (half of the roads have bike lanes around here and suddenly they disappear...).

According to the Highway Code:

Rule 64
You MUST NOT cycle on a pavement.

So the short answer is a definite no, although discretion is given for young children riding on the pavement.
This article has details the rules for cycling on things like footways, footpaths and bridlepaths.  (In short: no, no and yes - but the article is probably worth a read.)
More information about rules in other countries can be found in this question.


Can someone give me a short description and comparison of the different road cycling pedal / shoe systems? I am looking at buying a pedal/shoe system as the clips and straps I am using are hurting my feet again.

It's been a long time since I have bought a road pedal / shoe system, and I have forgotten the differences between SPDs, Look pedals and all the others.

Can someone give a short comparison of each pedal system with pros and cons of each? My usage is/will be mainly city street cycling and then road cycling (recreation, not racing).

I'd prefer if people would give the pros and cons of each and not their opinion on the "pedal system war".  :) However, "I use them because I find XYZ and it helps in ABC ways" is very useful.

First up, I'd strongly recommend switching to clipless pedals. I had the same discomfort issues you're describing with normal shoes and toeclips and find clipless pedal so much more comfortable and secure (therefore safer).

When comparing and evaluating clipless pedal systems, some of the more important attributes are:

Float - This is the property where the foot can swivel on the pedal while clipped in. Some pedals allow the float to be adjusted independently of the tightness, while other pedals have only a single adjustment for both. Also, see this answer.
Ease of entry - Some pedals require the pedal and cleat to be lined up carefully before the cleat can clip in. Others are orientation agnostic and a good stomp is usually enough to engage the cleat.
Compatibility with shoes - Most shoes have either the 2 bolt SPD pattern (typically mountain bike and more casual style shoes) or the 3 bolt SPD-SL pattern (typically lighter and more stripped down road shoes)
Availability - How easy it is to buy parts, cleats and pedals.
Surface area - The size of the contact point on the shoe. This can make a difference in how evenly the pressure of the pedal is distributed to the foot.
Walkability - How easy it is to walk while wearing the shoe with the cleat.

These attributes for a number of different brands are compared in the table below.

Shimano SPD

The most common style of commuter and mountain bike pedals.

Shimano SPD-SL

The most common form of road bike pedals

Look Keo

The first popular road bike clipless pedal.

Speedplay

The speedplay pedal is becoming more popular with many professional riders now using it. One advantage is that there are no moving or wearable parts on the pedal, providing exceptional durability.

Time Atac

The Time Atac is another mountain bike style pedal

Time equipe

Time equipe is the road shoe style Time pedals

Crank Bros Eggbeaters

Crank Bros Eggbeaters are commonly used on mountain bikes where their simple design is good at shedding mud. There is some question about the durability of the bearings, however replacement kits are available, making these pedals more repairable.


Why are my Shimano 105 11-speed shifter/derailleur acting like they're 10-speed? I recently got a pair of Shimano 105 shifters and a rear derailleur and put them on my bike. The front derailleur is a Shimano Tiagra, and the cassette is also Shimano. The cables are new, but the outer cables are old.

I managed to get the rear mech indexed correctly when I installed them, but the following day the bike wasn't shifting to the biggest sprocket. I tried to adjust the indexing, but if I loosen the barrel adjuster enough to shift to the biggest sprocket, the derailleur won't shift to the smallest one. Similarly, I tighten the adjuster until it shifts to the smallest sprocket, it won't shift to the biggest one.

If I pull on the cable and turn the cranks with my other hand, the derailleur shifts to the biggest sprocket but the chain drops back to the second biggest when I let go of the cable.

I have looked at the invoice and the packaging, and it says there the components are supposed to be 2x11, and I counted ten clicks from the shifter. What could be the cause of this issue?

Here are a few photos of the rear mech:

Rear view:

Now that I look at it, the derailleur cage seems to be in an odd angle. Here's the side view:

It's evident from your first picture that there is definitely a pretty bad derailleur cage alignment issue.

The derailleur hanger does not appear bent, but it does look like the derailleur bolt may be cross threaded , as the derailleur body seems to be at an angle to the hanger.

Check the derailleur installation and also check that the cage is not bent.


Where is the Shimano e-tube project light connection setting? I'm trying to install some aftermarket hardwired lights to my eBike which is running a Shimano steps e5000 drive system (bike is a Reid urban+ ebike). I've verified that the lights work and are the correct voltage, however when I press the light button on the headunit nothing happens, no voltage on the light terminals, and no response from the display (usually would display a light icon and beep).
I've tracked the issue down to a setting that needs to be enabled in the e-tube project software called "light connection." (excerpt from e5000 manual below:)

So because I don't own the expensive linking device - I went and brought my bike to the local bike shop and asked them to just enable this setting. Unfortunately they've told me that they can't find this setting in the software - and it's near impossible to find a manual for the windows version of the e-tube project software (I've only been able to find this manual for the app version of e-tube project).
Does anyone know where to find this setting in the e-tube project software?

Shimano hides this kind of information behind its TEC site. This is for 'industry professionals', but you can register by selecting some random bike shop as your place of work, there are no checks.
https://www.shimano-tec.com/
Here are screenshots from the relevant course https://www.shimano-tec.com/mod/scorm/view.php?id=2310

I downloaded the software myself, and it was extremely easy to find the setting following these steps:

from main menu click 'e-bike'
screen appears as in the screenshots above, but without the components (since I do not own them)
then after connecting to the computer and running 'connection check', you can select the 'drive unit' then click customize


27" x 1 1/4" back flip flop wheel or track wheel(rear) I'm looking for a good wheel, I don't know much about brands and what's reputable.  I'm replacing my back wheel because it's a suicide hub set up by a local bike shop(cheap short term fix)

I'm wanting to replace my back wheel without having to replace my tire and innertube so I need to match the current size.  any advice, or links to a wheel to buy will be very appreciated.

Current tyre size is 32-630.

The critical measurements are that you have to match the rim diameter to your brakes, and the width of your hub to whatever your frame needs.

A 27" wheel may be several different sizes.  Its best to use the ETRTO number which is 622-xx for a 700c wheel and 630-xx or 635-xx are nominal 27 inch.

So your existing tyre/tube will fit because the new wheel's rim has to be the same size as the old one.  Nothing else will do unless you want to risk needing a brake replacement.  If you have disk brakes then its a little more forgiving, but still not a good idea.

Also the new rim's internal width should be pretty similar to the width of the old rim.

If your existing rim's okay then you might choose to replace the hub and rebuild the wheel.  Its possible you need shorter/longer spokes at this point, and there's certainly no cost saving over a complete wheel if you can find one.


Chain really quite stretched, should I change cassette at the same time? I measured my chain last night - 10 links were 25.8-25.9 cm.  So I ordered a new one, tools and spare link pins (Shimano 8-speed HG).  I'm thinking this amount of wear might explain why my least favourite gears feel and sound not quite right, while the ones I use the most are fine (i.e. the favourites are worn with the chain).

A new cassette isn't much money, but changing the cassette makes for a much bigger job, and I'd have to buy the tools.  As it is, it's the first time I'll have fitted a new chain.

The bike probably has 2000-2500 miles of mostly tarmac, just enough dirty stuff to get grit everywhere, taking ~100kg up some reasonably steep hills.

EDIT: The difference between my question and this one is that the old question doesn't say anything about amount of stretch (though the answers there would tend to suggest the bigger job)

EDIT2: I finally got the chance to get a photo in daylight.  I don't like the way the chain is sitting (at the top) on the sprocket it's meshed with, though the 11 and the 32 are better than I thought -- I overlaid the image of the teeth of the 28 (little used) on the 32 (works quite hard sometimes).

The easiest way to tell is simply to install the new chain on the cassette. If the cassette is worn from the old chain, it will skip when you apply a decent amount of pressure (standing up will usually do this in your big ring and half way down your cassette). If it does jump, you'll need a new cassette. It's really as simple as that.

I would be surprised if you need a cassette. The lower model cassettes are made of steel and don't wear easily. (My current cassette, a Shimano 6700 is now 12,000 miles. I change chains about as often as you did and I do keep it well lubed).

You may notice a bit of noise when you change chains. I notice this also and it usually goes away after some mileage. If not, you can always try adjusting your rear derailleur a bit to see if that helps.


How to best quick fix worn out tyre I want to share my experience and ask for some further question on this issue.
I was on a roadtrip as I found out that tyre on my rear wheel was worn out. I could clearly see the threading (if this is correct name for that) on the side walls of the tyre near the rim. I swapped front and rear tyre to have the weak one in front because it gets less pressure. Was this correct thing to do? Also, should I have deflated the air pressure in tube when I saw this?
After some time, the tube punctured. As I examined it, the whole one side of the tube was worn out because the threading of the tyre rubbed against it. So there was a full circle of worn out material. Therefor, I didn't want to patch the tube because it seemed like it was already too weak.
What I did was cut that tube entirely open, wrapped it around new tube, stick it in place with some ducktape, and then put that tube inside a tyre. That way, the tyre could only rub on the outer tube, deform it, and perhaps even puncture it again, but the hole would have been too small to let the tyre reach the inner tube, and it seemed like pretty smart fix. What do you think about that?
Unfortunately, after some time, the tyre got so worn out that the threading start to break and a hole was made in the side wall. So, the tubes popped out of the tyre completely in form of a little ballon. At that point I had to stop and seek for new tyre.
But, I was in remote area and there were no bike shops, so I got some old tyre from some random guy that was also kind of worn out. It was worn out on the top wall (if that is the name of the part of the tyre where it touches the ground), but not as much as my old one. I put his tyre and it almost got me to a place where I could buy a proper new tyre when again the tube popped out in form of a ballon.
Then, I deflated the tube almost completely and walked the bicycle to the bike shop. Should and could I have put both my old and his old tyre to prevent leak of the tube? It seemed like a good idea, especially because they were damaged at different places, but I didn't want to risk some other stupid thing that might have happened. If that would have been a good idea, what about if the tyres were damaged at the same spot? Would then make sense having both of them? Two tyres and two tubes does sound ridiculous but in the means of necessity a lot of things cross my mind.
Also, I appreciate any other guidance on what to do in similar situation, or any sharing of your own personal experience.

Later:
Boot is something I wasn't aware that could be done and it sounds like a smart fix for a hole in the tyre. In my case, the threading of the tyre was damaged on the whole circumference of the sidewall, not from debris as Weiwen has assumed, just from being worn out. In that light, I think that old tube wrapped around new tube was better solution since there was no hole in the beginning. Of course, once the hole was made in a part of sidewall, I should have made a boot.
For some comments: I know I should have checked everything beforehand. I didn't. I hope this discussion will help someone other who gets into similar situation. Whether because he was stupid like me and didn't prepare, or did prepare but some bastard stole his panniers with equipment :-)

There are several questions here.
You were on a road trip and found a hole in your tire...

I swapped front and rear tyre to have the weak one in front because it gets less pressure. Was this correct thing to do? Also, should I have deflated the air pressure in tube when I saw this?

And...

Should and could I have put both my old and his old tyre to prevent leak of the tube? It seemed like a good idea, especially because they were damaged at different places, but I didn't want to risk some other stupid thing that might have happened. If that would have been a good idea, what about if the tyres were damaged at the same spot? Would then make sense having both of them?

To summarize:
You found yourself in a bad situation and improvised several amazing solutions using what you had on hand to get a little further down the road until you had no choice but to walk.
Your solutions were the best you could do in the situation.
Suggestions:
Do an equipment check and solve problems before you start your road trip. Identifying marginal tires, brake pads, etc. and doing basic maintenance before you start on a trip will reduce (not eliminate) issues on the road.
What your bring in the way of spares and tools depends on how long your trip is.
You brought a spare tube and the tools to install and inflate it - which is excellent. On your next trip consider bringing a spare tire. As a rule of thumb its nice to have a spare tire if you are going to be riding further from home than you want to walk back. Even if your tire is new they can be damaged while riding in a way that requires replacement.


GPS with maps for touring / using an iPhone We are going to do a bike tour through France and Spain with a friend at the end of the summer. I was wondering what is the best option for a gps. Ideally we want something with the ability to display maps. I know that sometimes it is possible to download some free ones off the internet (the ones they sell are really expensive!). Anyone has experience with this?

My budget is limited so I don't know if I can afford a Garmin 800 or even a 705.

The other priority is that it should have a more or less decent battery life. I personally prefer AA battery in case I cannot charge it somewhere.

By the way, has anyone used an iPhone for such a task? My friend has one. I can immediately think of a couple of drawbacks. First, the danger of breaking such an expensive gadget. Second, consuming all the battery very quickly.

I do mountaineering and trekking in the mountains as well so perhaps I wouldn't mind spending a bit more if I get something that I can later use on those trips as well.

If you have an iPhone or an Android phone there are various free options, some based on OpenStreetMaps, but even Google's own solution is excellent. For google maps you can download areas to store locally (for those areas you know you will have no connectivity) and it is free!

I'm playing a lot of Ingress at the moment, which requires 10 - 20 hour stints with my phone continuously running GPS, with the screen on (ie very high load) and my solution to the power problem was this 12,000 mAh battery pack from Amazon. It is only a little larger than my Galaxy S3 so sometimes I hold it with the phone, or I pop it in my rucksack.


How do I calculate calories burnt using my bicycle's weight? I've just finished a long bicycle tour on a loaded touring bicycle, and I'm interested in calculating the number of calories I must have burnt over the trip. However, all the calorie calculators I come across don't take into account the weight of the bicycle, which means the data must be a significant underestimate.

So, what is the calculation used to calculate number of calories burned on a bicycle ride, and how can it be modified to take into account the weight of a heavily loaded touring bike?

To be honest, you're really asking this question too late. If you had asked before your tour, I believe the easiest way you could have measured it would be to find a cycling app which takes your weight and your other physical information. Then you simply weigh your fully loaded bike and add that weight to your own, then the app would measure your total calories burned. (Even this would only be a rough estimate).

However, there is no solid answer to this question. As I said before, you would have been better off asking this prior to the trip, as there are dozens upon dozens of factors needed to give you an accurate BALLPARK of how many calories you've burned. (I.e. Speed, terrain, average gradient, food consumed while on your trip, average power output, length of time spent in the saddle, cadence, over all distance, e.t.c.)

I suppose if you wanted a very rough estimate, find a calorie calculator online, input the total weight, (you and the loaded bike), take the distance traveled, and the estimated total time in the saddle. This method would be fairly inaccurate, but without the factors listed above, I believe it's the closest you would get.


After fall bicycle feels really slippery I fell pretty bad this winter, and after that (even now without a trace of snow where I live) I feel the bike really slippery, mostly the front wheel. Riding on slightly uneven surfaces makes me feel I'm going to slide to the side, and side wind also feels I'm losing control of the bike.

Bike is less than a year old and I only commute with it, no long distances.

Could it be a technical problem or a confidence issue?

For the most part, whenever the front wheel on a bike skids or slides at speed, the rider wipes out. The only people that manage to stay up right are either very lucky or have reflexes that Jedi warriors would be envious of.

If you are riding after a recent fall and feel like your front wheel is sliding, but you are still upright, then you have some sort of post-crash confidence hit, and are interpreting any motion as being an imminent crash.

Check that your fork isn't damaged, handlebars are aligned, and that your wheels are true, but otherwise just keep riding and rebuild your confidence.


What is the purpose of chamois cream? I've seen it advertised but never used it, what's it for? Is it effective ?

Chamois cream is useful if one is getting chafing from rubbing inside a pair of shorts. I've found it useful in high humidity.


How can I fix panniers that have got holes in I've got some Crosso panniers that have got quite a few holes in. I once fixed a drybag backpack with patches of leather and industrial strength glue which worked like a treat, but I've forgotten what glue it was (it came in a large tin and I spread it on with a knife)- it was in the textiles department at the uni I was studying in. Any advice / links / tricks would be great.

If you have water proof panniers made of soft plastic, patches made for fixing holes in bike tubes are really great (depending on the size of the holes in the panniers of course).


Does bike geometry or wheel affect maximum cog size? I got a used Cannondale Super X 105 during the winter and when I was getting it ready for the summer, I couldn't index the rear derailleur properly. It wouldn't shift to the largest cog and shifting to the smallest cog was iffy. I took it in to a bike shop to get it looked at (full tune-up while at it) and the feedback was that the cassette (11/34 I think) was too big for the bike and the derailleur was too small (plus bent cage which I suspected). Tried to see if I could keep the cassette and get a larger derailleur but the mechanic insisted the cassette is not right and would need replacement. Maximum I'd be able to put on would be a 30T.
I've searched online to see if frame size limits your maximum cog size but couldn't find anything. So now I'm wondering if he was simply assuming I would want a same for same replacement of the bent derailleur.
I already spent almost $200 replacing all bearings and BB  (total blindside there) which was what I had budgeted for the drive train so I don't want to spend money I don't have to.

No the frame size doens't limit your cassette choice.  Within reason any 700c wheeled bike should take any available cassette size.
What matters most is the Derailleur's capabilities.   The maximum and minimum tooth count is a published value for each derailleur model.
Also in the stats are other useful values.
Presuming your bike is a 2017, it would have had a "Shimano 105 GS" rear mech.  (from https://99spokes.com/bikes/cannondale/2017/superx-105)
This might be the RD-5800-GS which is documented at https://bike.shimano.com/en-EU/product/component/105-5800/RD-5800-GS.html

Item
Value

Low sprocket_Max.
32T

Low sprocket_Min.
28T

Max. front difference
16T

Top sprocket_Max.
12T

Top sprocket_Min.
11T

Total capacity
37T

So nominally this combination would take a largest cog with 28/30/32 tooth.  The smallest is 11 or 12T, so it wouldn't work well if the little cog was a 14, and probably jamb up on a 16T.
Shimano's specs are notoriously conservative, so this combo probably runs fine on 34T but would be nominally "out of spec"

That said, there might be something special about your bike which the mechanic has noticed, but not come across in the text of your question.  Adding a photo might help.


Can I use a Vittoria Zaffiro 700 * 25c road bike tyre with a hole in outer rim of the tyre? My road bike tyre got punctured couple of days ago and I just noticed that it resulted in a hole in the outer wall of my tyre. How can I close this hole? I rode just 500kms on this tyre so I am not sure if I need to replace it with a new one

Install the tire and pump up to pressure and see if there is any bulging which would indicate the chords are damaged. Damaged tires belong in the trash.

If there is no sign of chord damage and you decide to use the tire, I would strongly suggest 2 or 3 layers of duct tape or similar as a patch on the inside.  Not only will this provide additional strength but it will reduce the chance of gravel or debris getting into the hole.

FWIW, for small holes such as this I will use Shoe Goo to fill the hole and prevent debris from getting to the tube.  First I inflate the tire to a pressure above where I ride and then work some Shoe Goo into the hole. After the Goo cures overnight and the tire pressure is reduced to normal, the tire will squeeze the hardened Goo and hold it better.  If unfamiliar with Shoe Goo, it was originally marketed for repairing worn tennis shoes. It goes on like silicon caulk, remains flexible but is much harder than caulk.

Last tip: The repaired tire is always installed on the back wheel and I position the repair at the valve stem so I can easily check for any signs of bulging every time I inflate the tire.

Shoe Goo


Can cycling improve my stamina in soccer? I cycle about 2 km uphill every day, and it takes me about 16 minutes on my MTB.
I hope this will also improve my stamina in soccer as I am unable to sprint/run fast.
Please suggest me some good diet.  I am allergic to eggs.
I am 20 years  male  and I weigh 74kg ,height 5.6 ft. Is my body weight OK or bad?

If you want to run fast, you need somewhat structured training. Normal bicycle commuting is certainly beneficial to ones health, but without structuring it it will be often too short fort endurance training or too slow for speed training. If you want to be fast (on the bike, but there is some limited overlap) you need to train shorter fast sections - like sprints and short time trials. If you want to have endurance for long activities, you need to train long rides. Those can be your commutes, but you would have to significantly extend it.
The overlap to running is there but is not perfect, the sports use different muscles to some extent (as I reminded myself painfully when returning to running very recently), but at least you use the same lungs and the same heart - but also many common muscles.  You will certainly also need to train running specifically and the same logic applies. Short fast intervals for speed, long runs for endurance, but there are many detailed advices on running-specific sites.
Discussing your diet is really a completely different topic and cannot be done here. Look elsewhere, but normal healthy diet with balanced income of basic nutrients should be the start.


What is an alternative hitch for the Re~Cycled bike trailer? What is an alternative trailer hitch for the Re~Cycled bike trailer?  This is the webpage of the trailer http://www.re-cycle.org/sites/re-cycle.org/files/Trailer.pdf

The reason I don't like it is because it tends to spring open and closed. Maybe use a ball and rod like this?

Simplest answer would be to find a trailer that you like that sells the hitch as a spare part, and use that.
For example http://www.carryfreedom.com/hitch.html


My rear rim is worn off by braking My rear rim had those small indents in it for rim brakes, they have brushed off now.
Can I re-indent those dots to make braking efficient again. My rim is double walled mtb compliant.

No.  That indent or wear groove is to indicate the amount of wear on the rim.  If you can no longer see the indent, it means the rim is worn and should be replaced.  Sheldon Brown's take.  It's similar to if you no longer had tread on a tire.  You couldn't re-indent the tire to make new tread.


I shortened my chain, is this bad? H, I'm pretty new to bike maintenance.

This weekend I tried breaking my chain to clean it. This went well up until I accidentally popped the chain pin out and as a result had to remove a link. This chain came with the bike and AFAIK was well fitted before. It's a near-new hybrid commuter road bike. It still rides OK.

My question is, should I be at all worried that my chain is now about 1.5" shorter? How much leeway would be typical in a new bike? What rules of thumb exist around chain length?

"Never run with a chain that is too short, except in an emergency." (from Sheldon Brown's Derailleur Adjustment page). If a short chain ends up on the big chainring and big sprocket at the same time, then the derailleur will probably get damaged.
To avoid damage, there should be at least one full link of overlap when the chain is put around the big chainring and big sprocket (with the rear derailleur bypassed).
Unless the chain was too long to begin with (which is unlikely), you should get a new chain.
You can also by a single link instead of getting a whole new chain, and if you get a replacement master link, it will be easier to disassemble your chain for cleaning in the future.


25.4-27.2mm seat post shim on a seat tube with 26.8mm inner diameter From where I live (Philippines) , there seems to be no stock for 26.8mm seat posts. All other sizes are available except for 26.8mm; they don't even sell shims for that size. Currently I am forced to use a 25.4mm seat post on my bike.
Is it possible to use a 25.4 - 27.2 mm shim for that purpose? I've used beer cans and inner tubes for shims, but both options has led to the seat tube crimping as I tighten it down.

There are many different standards for seatpost size, and 26.8mm is one of the more-common ones.  Its not rare.
I suggest you buy the right-sized seatpost.  If your LBS won't order it, then look to buying one online.
A shim is a solution but as you found there are drawbacks too.  Bodging a shim from a can is really only workable for 0.2 of a mm at most.  More than that and you'd want a proper shim which is at least 100mm tall.