Is it safe to ride a steel bike with a dented/buckled frame? I just noticed, to my great sadness, a small-ish buckle/dent in my diagonal lower tube. (I'm riding a Cooper T200 single speed.) I just moved house; I hope I didn't do it. I probably did.

It's about half way up and looks like it's been bent against something, or crushed between something - the tube itself is still straight, it just has a bit of a ding. It's probably only dented in a fraction of an inch.

A fraction of an inch is no longer a perfect circle, though, and it'll inevitably weaken it. Question is, enough for me to worry about? Or should I just keep riding and forget it?

I ride on roads, to work, nothing strenuous, but want to be able to hit the occasional pothole or what have you without constantly thinking that my frame is going to collapse under me.

Does anyone have any actual experience with this sort of "injury"? Any suggestions how I might fix it, short of replacing the tube? I don't care if it looks a bit rough, we're through the honeymoon period, it's just a functional machine now. :-)

Thanks all.

Edit: added pictures, even though this is answered. Note that the other side of the tube to the visible dent is still perfect. (These are the same dent, from slightly different angles.)

All steel frames of any age get a few dings from serious use.

The failure point for steel frames is usually the highest stress points: the joins. That is why we used to have fancy tubing sets likes Reynolds 351 double butted, and I notice that your frame does too.

So, if the dent is away from the joins I say the frame is ok for general use. Steel is quite a forgiving material, but I wouldn't be doing bunny hops on it :-)

If the dent is within 25% of the tube length, but more than 10cm (4 in) from a join, then I would be using it, but cautiously. If it's closer than 10cm from a join then I would get a shop to look at it.

I would add that I've ridden high-end bikes for decades after their first (heart breaking) dents. One of them has just died, but a fork failed (at the join), not the dented frame.


Need help picking the right rear derailleur and chain for Giant Escape 2 Product page for the bike i have: http://www.giant-bicycles.com/en-us/bikes/model/escape.2/14810/75679/#specifications

I'm not able to make sense of the variations of shimano altus derailleurs,
here's one:
http://www.amazon.com/Shimano-RD-M280-Altus-Rear-Derailleur/dp/B00WY0NRYA

And would the , KMC Z7 6/7/8-Speed 116L Shimano HG, be a good replacement chain?

All 8- and 9-speed Shimano mountain derailleurs are compatible. Just pick one that you like. The one thing to worry is long cage versus extra long cage, and unless you know you have an extra wide range of gears, long cage is fine.

The chain is also fine. If you are changing the chain because is worn out or "stretched", you should probably replace the rear cogs too.


Bike Rack for Hatchback vehicle? I have a hatchback-style Vehicle (2007 Ford Focus) and a KHS Urban-X Bicycle.

Are there any standard styles of mount that work best in this situation?
Can you recommend any in particular or point me towards particular styles?

Thanks!

My answer only applies if you will be hauling your bike(s) frequently or somewhat frequently. My solution may not be worth it for occasional use, because one would need to invest in a trailer hitch for mounting the rack.

Get a trailer hitch like this: (Notice that the "trailer" hitching part is removable and the bike rack fits into that spot) And then choose one of several trailer hitch bike racks.

You may or may not haul a trailer, however, the bikes will ride a hitch mount just fine. With a hitch mount you don't have to worry about overhead clearance or (usually) the inability to open the rear hatch of the car.

My hitch mount can haul 4 bikes, (and I can still open the trunk) but I haven't used the total capacity yet.

Why do I like this?

The bike rack locks onto the trailer hitch in 5 minutes or less
The bikes are situated in 15 minutes or less.
I'm good to go. I don't have to worry about strapping things down or getting the trunk open, or overhead clearance.


Connect a classic raleigh dynamo hub to a lamp? How do I connect a classic raleigh dynamo hub to a lamp please?

Modern lights run on 6 volts. The front light is 2.4 watts and the rear is 0.6 for a total generator output of 3.0 watts. The first thing to do would be to see if you have one wire connection or two. If you've only got one then the dynamo is probably built to use the frame of the bicycle as ground. If there are two then one is the hot wire and the other is ground. With older, halogen, bulbs the polarity (which wire on the dynamo you hook to which wire on the light) doesn't matter. Modern LED lights may care, so use a meter to figure out which wire is which – you may also be able to tell by looking carefully. The ground, or negative, wire is usually marked in some fashion. Typical markings are a white stripe or a ridge on the wire.

After sorting out the connections, you need to know the voltage. See if you can find a readable rating on the dynamo, or failing that put a meter on the outputs and spin the wheel – the voltage will probably vary with speed, but it shouldn't be too hard to tell if you're getting something close to 6 volts at normal speeds.

If you have 6 volts then you should be able to hook up a modern light. Just connect the wires (if there are two), paying attention to the polarity. If there is only one wire connect the positive from the light to it and the negative to the frame of the bicycle. If you connect a light and nothing happens, try reversing the wires it may be that you have the polarity backwards.

If the output of the dynamo is more than 6 volts, you have a different problem. Too high a voltage will damage the light. So if the voltage seems too high, start by connecting a light that works and spinning the wheel at a slow speed with a volt meter attached. Watch the meter as you spin the wheel. Sometimes a load on the generator will bring down the output voltage. Again at normal riding speed the dynamo output should be right around 6 volts.


How I can see who watched my Strava profile? I have strava account,
Can I somehow see who watched my strava profile or my strava activities?

No, you can't.  You can only see who is following you, not who is just looking at your profile/rides.


conversion to rigid fork Is it possible to put a rigid fork onto a 120mm travel hardtail without upsetting the handling?

I used to ride a Kona P2 fork on a 96 AA frame, which I suppose was designed for a max. of 100 mm travel and that worked fine.

I have to get a new frame, am eying up some rigid ti frames but the ones I like a designed for 120 mm travel, so I am a bit lost.

You can purchase suspension-corrected rigid forks which are designed to work with the geometry that suspended frames offer (Essentially the axle-crown measurement places the head tube where it needs to be. Pretty simple.) There are a few manufacturers out there, but my favorite is Surly (in terms of quality and in value. They offer several forks for 26"-29" with disc and canti options.)

While installing a non-suspension-corrected fork might not totally ruin the handling of a particular bicycle, it would be VERY noticeable (as 120 mm is a good bit of distance to be dropping the front end of a bike.) It will be worth the investment.


Mountain bike trainer tires I received a trainer that fits my mountain bike. I am trying to find a tire that is quiet.

I can't find any online that are the same size as my current tire which is 26 x 2.25. I found only one close which is the WTB ThickSlick Comp tire 26 x 2.0. No real trainer tires at my size.

Any recommendations on trainer tires at this size? or will a 2.00 tire fit on a rim that holds a 2.25?

On a trainer that supports the bike, normal tire rules do not apply, as the tires don't have to support the mass of you and the bike, nor provide any lateral grip.

How narrow tire you can drop down to depends on the actual width of the rim, not the width of the original equipment tires. You can probably fit a tire that is not much wider the the outside width of the rim.

I've run a 1.5" hybrid bike tire on a MTB wheel on a trainer with no issues.


Heart rate during a ~1 hour individual time trial? I'm wondering about heart rate data during a flat(-ish) Individual time trial that takes a bit below 1 hour to complete at elite level, like the typical ITTs in TdF. I know HR alone is far from the big picture but I remember reading about average HR during marathons and variability was remarkably low, irrespective of finish time. So does anyone know the average/max heart rates of well trained cyclists during such efforts?

This is absolutely specific on the heart rate zones of each individual. Each person has a different heart rate at their functional threshold (FTHR). Professional cyclists are able to cycle for a long time (most of the road race) almost at their functional threshold but the actual heart rate is completely individual. Even the percentage of the functional threshold heart rate to some "maximum" heart rate will be individual. All these values must be determined by an appropriate physiological stress test to be reasonably accurate.

See, for example, https://cyklopedia.cc/cycling-tips/what-is-ftp-in-cycling/#1

When it comes to the maximum heart rate, that is not a very reliable value (may vary strongly for different activities) and it is much better to start all you zones and comparisons from your FTHR than some percentage of some maximum.

As a good source of example pro-cyclist heart rates you can use https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572307/ although it uses a longer race.

  The HR during the race was 158.9 ± 10.6 bpm (86.4 ± 2.2% HRmax), and
  exercise intensity is categorized as vigorous intensity.

As you can see, the variance for the heart rate is higher (more individual) than the variance of the maximum percentage.


Anyone seen a hollow crank spindle cut through by an internally-routed derailleur cable? I just want to share a recent observation, but I have to pose it as a question.
A person showed me an FSA Gossamer 30mm hollow crank spindle broken into 2 parts. The break looked almost as good as a machined cut from a lathe. He explained that his frame has internal routing of the gear cables, and that having changed the rear gear cable some time ago, eventually the gear cable wire had sawed through firstly the plastic sleeve cover, then finally the spindle.
Rather an expensive lesson learned here, in that he needs to replace at least the right crank c/w integral spindle. I just wanted to document the occurrence which may help others in future.

As clarified in comments, this frame appears to have a 30mm spindle crank with a bare derailleur cable somehow routed internally through the bottom bracket. I surmise that maybe the cable didn’t cut all the way through the spindle, but it might have abraded through the spindle enough to cause a stress riser and later a fracture.
While I haven’t worked on internally cabled frames, my understanding is that most current designs should use full internal housing, I.e. cable housing is pushed through openings in the frame, rather than leaving bare cable. I am not sure how the routing was done on this frame. I am also a bit surprised to hear that bare cable was rubbing against the spindle. If you aren’t routing full housing through the frame, I would imagine there has to be a cable stop to keep the cable under tension. If the frame was designed so that the cable was actually in contact with the BB sleeve, then that does seem like a very elementary error. Basically, I have not heard of this particular issue, and I am surprised by it. It sounds like something might be missing from the story.
While I’m not a frame designer, it does seem like many metal BSA shells with a 30mm spindle would have little room for internal cables or wires. Frame designers may choose to route hydraulic hoses externally at the BB, I.e. the hoses enter the down tube, then exit around the BB, and either re-enter at the chainstay or just get zip tied to the chain stay. One example is the 2021 Trek Domane aluminum bike, photo below from a review by Cyclingtips.

In general, if you have housing against bare metal or carbon, then if the latter is moving, you introduce the risk of fretting. With some current generation frames with fully internal cables/hoses that are routed against the fork steerer, I wonder if this will become an issue over time. At least some bike reviews on Cyclingtips have raised this as a possible issue, although I forget which ones. That could be solved by putting some sort of foam or rubber insulation against the house or cable housing.


Name of colour of paint on Kink Volte BMX I am looking for the color name for restoration on my kink volte?
serial # aca10e001651
Any ideas would help. I'm hitting a brick wall with google.

Sadly serial numbers are useless - they're not a VIN like cars have and only mean something to the manufacturer, who may have encoded info in the number, or may not even have kept track of the numbers.

If you have a sample of the paint you want, take it to an automotive paint specialist and ask for a colour match.  Not your local big-box store, somewhere that just does car paint.  Explain what you're painting, and whether the sample is fresh or faded, which will give the mixers extra info.   You can generally get the paint installed in a spray can.

If you don't have a sample, try and get a good photo of a suitable bike.  Ideally a photo taken in sunlight would help.

Don't bother matching colours.  Just pick a shade that you like and go from there.  Consider what decals you have and get a contrasting or tonal matching colour for the labels.

Either way - get clear coats as well to protect the paint and decals/stickers.

Try a powder coating company - this is a baked on plastic-like finish that is super hard wearing.  You may be limited in the colour selection to the powders that are on hand.  This stuff doesn't need a clear coat, but you will have to clean and prep the frame perfectly including blocking all machined surfaces and threads etc.

Try contacting Kink directly at  https://kinkbmx.com/  though this may get ignored.  Doesn't hurt to try.

Your bike is your bike, build it how you want it to be.


Stuck nut on bike axle? I've got a bike. There is a stuck nut on the axle, and when I try twisting it.. well.. the axle turns too (obviously.). I'm trying to get it off, but it won't come off. My grandfather has a vast arrange of tools in the garage, so I have a good chance of finding any tool I need to get this pest off. WD40 is also in there. If you can help me and tell me how to get it off, please do!

The first approach to take is try to immobilize the axle by getting the other side dropout extra super duper pinched between the locknut and axle nut. If that side's axle nut can be freed, remove it and grease the threads. Snake in a cone wrench and open wrench on that side if applicable and get the cone and locknut very tight against one another. Then with a wrench on the cone if possible or the locknut if not, reef down on the axle nut. You may get more preload by adding a washer if it doesn't have one, and you'll tear up the dropout less. Then try again on the stuck nut. If you can put a wrench also on that side's locknut while doing so, it will help to immobilize the axle. (If you have access and think it will work, you could also just try putting a wrench on that locknut without doing the other steps. That will be enough some amount of the time.)
This only takes a minute and usually it just works.
Depending on what locknuts you do and don't have access to, another approach can be do the above to the extent possible, then try to break free the offending side's cone and locknuts from each other, then do wrenches on that side's axle nut and locknut.
Getting penetrating oil on the stuck nut will help with any of the above.


Can someone help me identify this old Shimano derailleur? I want to poke around online a bit and see if I can find anything out about it. It's a long cage, on an old 18 speed Univega MTB. Thanks.

I can't find the exact model, but it looks very similar to this one that I found on VeloBase.
If you have the patience check out this list. Shimano starts around page 8.
I suspect it might be a bottom of the range version of a Light Action, but I'm far from an expert
EDIT:
I think it might be this one. You're fortunate I stumbled across this question when I was in the mood for a bit of a treasure hunt :)


Coping with crash fear? This will be my first season racing collegiate this spring and I recently crashed on a group ride going about 22 mph around a corner and slammed my face into the ground. Crash was pretty bad and had road rash across my body and tons of stitches in my face. Before the crash, I had gotten really good at cornering at high speeds and was comfortable in doing so, however, now, I can't even take an easy corner at any speed without being way too wide and being fearful of falling. Any tips on overcoming my fear so I can get back into the crit-racing mindset?

Some people never do.

In races, people push to the limit, and sometimes past it. And people make mistakes. So there will always be crashes.

It's part of race craft to learn to read the corners and your competitors, to know when to make sure you are ahead or inside the risky riders.

At this early stage of your career many of the riders you are riding against are enthusiastic learners. Some strong athletes can't cope with the risks and drop out of Crit racing or ride at the back to build condition for other kinds of race.

You don't say anything about how the crash happened. It might sound unkind, but you don't have to fall when someone bumps into you, or falls in front of you.

Keep at it. Try riding at the back for a while to watch and learn. And watch other higher grade races.


Trying to replace a wheel I am a big dude, I weigh 250 lbs, and I kill bikes.

The best thing I have found so far is putting 12 gauge spokes on my Mt. Bike, which has reduced the number of spoke I break monthly.

I have a Cannodale Adventure 5, and I destroyed the rear wheel in February.  Anyhow, it had 700c wheels, and I want to replace the 700c wheel with another, but with 12 gauge spokes.

I've been to 2 bike shops, and they seem confused, asking questions like

how did it break,
how many spokes do I break in a year?
do I have them fixed?
why do things wear out so fast for me?

... which all comes back to being a big dude putting loads of miles on a bike.

They want to know more pertinent things too, like freewheel or cassette, and type of rim. Which the answer is I don't think I care. Then they ask other questions like what the wheel spacing is, and I have no idea what that even means.

So, what details do I need to be able to replace a wheel for a frame which I do not have the original wheel to?

What details should I consider to get a sturdy wheel for someone of my girth?

First off, the number one cause of broken spokes is not enough tension. When spokes aren't tight enough they load and unload with each revolution of the wheel – basically they are getting bent back and forth each time they go around. Over time they break, just like bending a paperclip. The most likely place for the spokes to break are at the bend at the hub.

Any good wheel builder knows this and will take great care to get the spokes uniformly tensioned. Once the spokes are tight enough they don't load and unload on each revolution and they will last a good long time.

Here's what you need to know to order a new wheel:

The size of the wheel: 700 C on your bike.
The rear dropout spacing: you can measure this by taking out the rear wheel and measuring the distance between the dropouts (the part of the frame where the wheel attaches) in millimeters. Odds are good it will be 135 mm, although 130 mm is also likely. They need to know this to choose the right hub width.

Beyond that the wheel builder should be telling you (or at least making recommendations). I think the bike shop questions were being asked to learn about how you ride and care for your bike.

Unless you've been riding hard (jumping curbs, bouncing through pot holes, etc.) I'm very suspicious that your spokes were too loose. Really, you're not "too big" for a decent bike. Trek, for example, says their road bikes are good for riders up to 300 pounds, and mountain bikes are good for 275 (if I recall correctly). I'd guess that the mountain bikes are lower due to the rough service they are likely to get.

Some things I'd expect your wheel builder to recommend:

Don't use heavier spokes, use more. I'd go with more (at least 36 or even 40). On our tandem our wheels are built with 40 14-gauge double butted spokes. They are holding up just fine, and our team weight is 360 pounds, with the bike and bags the load is up around 425 pounds. We're using nice sturdy rims, but the big thing is that I built them with good tension on the spokes.
Use the biggest tires that will fit and run them with relatively low pressure. This will enable the tire to absorb road shock, and being big it let you run a lower pressure without risk of "snakebite" punctures in your tubes.
Consider using an asymmetrical rim in the rear. Asymmetric rims offset the spokes to the left a bit to help equalize the bracing angles of the spokes (on a symmetric rim the drive side (right) spokes are much tighter because they are at a steeper angle. This is because the flange of the hub is moved to the right to make room for the cassette.


Sandals in the winter? Other winter footwear options? I used Shimano cycling sandals during the summer months here in the Chicago, Illinois area.  I'm wondering if I can use these during the cold winter months also or if different shoes are required.  In favor of continuing to use the sandals, I could add SealSkinz and/or wool sock layers as the sandals are expandable.  Other than looking strange in the winter, are there problems with doing this?  What other winter cycling footwear should be considered?

I go through 3 different types of shoes as the seasons change:

Hot (80F+): sandals
Variable (30-80F): indoor soccer shoes (eg adidas sambas)
Cold (30F-): light hiking boots/trail running shoes

For cold weather, you not only need to be comfortable while pedaling on your bike, but also confident off your bike. Lightweight hiking boots, with windproofing, waterproofing, and breathable layers, not only keep your feet happy while pealing but also let you feel like a mountain goat when you put your foot down in the slush at a stop light, or dismount on top of ice, or have to portage down wet stairs. Trail running shoes with these attributes are also a great choice if you want something even lighter and without the additional ankle support.

As others mention, wool/smartwool socks and switching to platform/toe clip/half-clips on your pedals are both good changes in addition to changing up your footwear. My winter setup is smartwool socks, size 13 light hiking boots from North Face and Velo Orange half-clips.


What rear mech can I use with 105 shifter? I would like to use a set of 105 shifters (10 speed), but I don't have a rear mech yet for them.
I would like to purchase a mech that would allow me to use a big cog cassette, like a cyclocross or mtb one.
What is the compatibility with other models, like mtb mechs?
Thanks in advance

It depends on what you mean by big, which can now be interpreted many ways.

Without doing anything too tricky, you can run them with any 9-speed Shimano mountain derailer, some of which can natively handle up to a 36t, RD-M592 being a currently made and easily available example.

10 and 11 speed Shimano mountain rear derailers use different actuation ratios, so they can't go directly on your shifter, but they could be made to work using something like a Jtek adapter or Wolf Tooth Tanpan. If you wanted to run a 40 or 42, you could use a Wolf Tooth Goatlink on an applicable 10-speed RD that you also have a cable pull adapter on.

If you want to use a road RD, you can go up to a 40 with a Wolf Tooth Roadlink. It's important to understand that they increase the clearance but not the capacity of your RD, so whether it makes sense depends on what's going on up front. (True no matter what route you choose actually.)


Upgrade Peugeot 5-speed to indexed flat bar shifters My girlfriend got a vintage Peugeot with original 5-speed cassette (2 front gears) and friction stem-shifters (with a flat bar). She's struggling with the shifting. I'm considering the following upgrades:

Replace the stem shifters with 5-speed twist shifters. Would I need to also replace the rear derailer in that case?
Replace only the rear derailer (and maybe the cables) and see if that makes it easy enough for her to learn friction shifting.
Alternatively, I could go with new 6-speed parts: shifter and derailer. But would that mess up the shifting since the cassette is still 5-speed?
Replace the front derailer as well, but not the front shifters. So I'd have twist (indexed) rear shifters and stem (friction) front shifters. Is there any reason that wouldn't work?

Which of these would you recommend? Are there any important things I should be aware of/look out  for (I've not done a bike project like this before)?

If the goal is to make it easy and work well, for sure get a modern freewheel, like a Shimano 6-speed hyperglide one. Hyperglide style ramping is the glue that holds indexed shifting together. Even if you jumped through all the hoops needed to try to make it index with the freewheel you've got, it wouldn't work.

A lot of gripshifts threaten to take up too much room on the sort of bar it probably has, so good idea to measure that ahead of time (adding in the length of the grip you'll use).

If it can fit them, then a good cheap approach would be getting 6-speed MRX comps with the semi-index aka non-index left (lots of small clicks) plus almost any cheap MTB/hybridy rear derailleur and the aforementioned freewheel, plus a new chain. You could even get the rear gearing lower this way, which is good because that sort of bike didn't come with very thoughtful gears. You could do the same thing with similar thumbshifter sets, where the left is friction and the right is 6.

Making the front index is a whole other ballgame and usually would require replacing the crank before it works smoothly, which isn't necessarily bad depending on how hard you want to commit to the bike.


Bottom bracket harder to turn half way around does this sound like a I need a new bottom bracket ?
When I turn my cranks with no chain attached, it's pretty smoothe, no real noise and just goes for a while if I let it spin.
When I attach the chain I can turn about half a rotation freely and then it becomes stiff and seems to be in the same place each turn.
I think my bottom bracket is press fit type - it looks like cartridge bearing on either side - I've probably done a couple of thousand miles.
I did just change the cartridge bearings in my rear wheel & hub, think my chain is worn between 75% & 100% from the tool I used to measure.
this may be unrelated but im riding a lot on a turbo trainer - something is causing the chain to vibrate a lot in the lower / harder gears - but appears to be indexed fairly well.
Thanks.

When I turn my cranks with no chain attached, it's pretty smooth, no real noise and just goes for a while if I let it spin.

This does not look like a bad bottom bracket.

When I attach the chain I can turn about half a rotation freely and then it becomes stiff and seems to be in the same place each turn.

However, chain and other attached stuff creates a side load onto the bottom bracket, which may skew the crank axle a bit, and that may reveal looseness in BB's bearings.
Have you tried to wiggle the cranks side to side by hand when they are installed? If you can see or feel noticeable play, then it is a sign of worn bottom bracket.


Performing a manual on a road / gravel bike I've been trying to improve my manual technique. I ride a Hakka MX and want to get better at manuals so I can better negotiate drops and whatnot on MTB trails.

I'm having a hard time getting the front wheel up enough without also giving some power through the pedals. And then it's a wheelie, not a manual.
I'm wondering, is this a consequence of the geometry of the bike compared to a typical MTB? (No dropper post, lower stack, longer reach...) Or just a consequence of my technique?

You are correct. The geometry of a road bike leads to a different body weight distribution than you would have by default on an MTB, BMX or other type of a bicycle. To lift the front wheel, you'll need to shift your mass center to the left of the rear wheel's axle to ground projection, that's just statics in physics.
You can ease it slightly by e.g. installing a shorter stem and by lowering the saddle, but it still would not be enough to make it as easy as it would be on certain other bicycle types.
It is not impossible, you may find videos on the Internet of people doing manuals, front manuals and whatnot on road bicycles. By as for the beginner, it would take much more time and frustration to learn it on a road bike frame.


Difference between two drivetrains with the same gear ratio? Given two identical, fixed-gear bicycles, one with a 36/12 gear combination and another with 48/16, will there be any noticeable difference when pedaling these two bicycles?  I understand there may be some negligible differences due to differing amounts of chain wrap on the cogs, etc.

I have a friend who alleges that, despite those bikes having identical gear ratios, the 48T chainring will be "better" for a rider preferring a lower cadence and the 36T chainring will be "better" for a rider preferring a higher one.  I've attempted to explain to him that this would require the bikes to somehow have differing amounts of development per pedal rotation, which they do not as I have tried to demonstrate here: http://www.gear-calculator.com/?GR=SGLS&KB=36&RZ=12&UF=2240&TF=90&SL=2.6&UN=KMH&GR2=SGLS&KB2=48&RZ2=16&UF2=2240

Please help me win this argument!

The gear ratio is exactly the same, the only possible difference is in the efficiency of the power transmission. Big/Big is generally more efficient, so it should be better for both, unless there is some reason that greater power losses in the transmission chain help "spinners".

So they will potentially feel different if you can notice the difference
( pretty small ) in the efficiency of the drive train. I don't see how that translates to masher vs spinner though.

http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf


How to increase friction on a Shimano SIS+Friction rear shifter when it is in friction mode? I'm using some Dura Ace SL-7700 downtube shifters on my road bike. I bought them NOS.  The right (rear) shifter has the D-ring for switching from SIS to friction mode.  It's a bit strange that the user manual didn't include mention of the friction mode, and while the D-ring on the shifter itself does have the little triangle marker that points to "SIS" stamped on the lever, the lever doesn't have 'Friction" stamped a quarter-turn away like it does on my older 8-speed shifters with the same feature.  Yet, if I turn the D-ring a quarter-turn, just like with my 8-speed, I get friction mode.

However, I feel like the friction mode doesn't have enough friction.  The front (left) shifter has plenty of friction, and it is easily adjustable by turning the D-ring.  What do I do to increase friction on the rear (right) shifter if the D-ring is used to change between SIS and friction modes?

There should be a screw opposite the D-ring that you can tighten down to increase the friction on the shifter. On a shimano shifter a flat head driver should be used, but you can use something like a dime if you're in a pinch.


Flat handlebar caliper brake compatibility I am trying to convert my flat bar bike to drop bar. I have bought STI's but I also want to use additional brake levers(like cyclocross bikes, flat bar levers) as well.

I may be wrong but cable pull ratio of caliper brakes(which I am going to install on my bike) must be different so I think I can't use my old levers with caliper brakes. This is my first question, V brake levers can be used with calipers?(I think no)

Now I am looking for a suitable brake lever. But how can I understand if I can combine them with STI's and caliper brake? Do they have a name like "Flat bar road brake system"? I have taken a look to some bike stores on web, they only tag "v brakes" and "road brake shifters".

The product you are looking for is interrupter levers. regular flat bar brake levers aren't designed to work in conjunction with STI levers.  The ones I linked to specifically say they are compatible with caliper/cantilever brakes.  I'm pretty sure most interrupter levers would be compatible with caliper/cantilever brakes because v-brakes don't tend to be found on bike with drop bars, which is where one would normally need interrupter levers.


Noise when pedalling What is causing this noise? Is it normal?

I found the source:

The chain and the other thing (I'd love to know what it's for by the way) were too close. The image is showing them after the adjustment.


Freewheel vs cassette geared hub motors serviceability With ebike conversion kits there appears to be 2 types of rear hub motors: the ones that accept a cassette and a freewheel (see the image below from this aliexpress item)

Is the freewheel option more serviceable?

I mean when I'll be replacing the freewheel I'll be replacing worn out sprockets together with the ratchet mechanism.
Whereas with the cassette option the ratchet mechanism comes with the motor and I'll be only replacing sprockets and if there's a need to replace the ratchet then I'll have to replace the whole motor or is the freehub part with the ratchet that the cassette attaches to also replaceable?

Or is the freehub on the image above just screws on top of the freewheel attachment threads?

Whether the freehub rachet mechanism is servicable depends on the design of the hub. Nominally the pawls and teeth are separate steel parts in an aluminum hub body and therefore replaceable; but only if the hub manufacturer makes spare parts available.

Something else to consider is that the freehub version will be substantially stronger. The drive side bearing is further inboard on the freewheel version making the axle prone to bend or break.


How safe is to use 700x25-32C tube on a 32C tire? I know this question begs a clear "of course" answer. But is there any drawbacks stretching the tube to its maximal proportions provided by manufacturer?

Are tubes even more elastic/stretchy so using maximal width isn't nearly as much as this tube can handle? I always worry that inflating the tube to 80-85psi and maximal width can lead to more frequent, irreparable flats.

It is completely safe and shouldn't be of concern.  The only existing questions I can find discuss using an undersized tube (18-23 in a 28 tire, 23-25 in a 32 tire) and even those cases might work.  (If you've ever pumped up a tube to find a puncture, you've seen that tubes typically can easily expand far more than their rated size.)

The tube doesn't contain the pressure; the tire does that, so max pressure is purely a function of what the tire is rated for.


Comparing 'upright-ness' across several endurance road bikes I'm comparing the following endurance road bikes, all in 58cm or L:

BMC Roadmachine
Cannondale Synapse
Trek Domane
Look 765 Optimum
Specialized Roubaix

I'm 6'2" and recently recovered from a herniated disk and hip arthroscopy. Given that, I'm looking for a geometry that is "upright" in riding position.
How can I best compare or measure 'upright-ness' between these bikes?
I know the basics: shorter reach + longer stack == more upright. But those measurements actually seem to conflict here, and I'm not sure the degree to which other measurements may counteract them. For instance, the Roubaix has the longest stack, but also a relatively high reach and the shortest head tube length. The 'best match' seems to very widely by different categories/measurements.
Is there a slightly more nuanced way to compare this measure between the bikes shown here?

You're almost there. You can quantify "uprightness" as the stack/reach ratio. Just add another row to your spreadsheet and insert that formula.
I'd say anything over 1.5 is pretty upright; down around 1.4 is pretty racy. You can compensate to some extent with spacers and stem length.


What is the difference between different types of disc brake pads I've seen several different descriptors for disc brake pads: Metallic, Semi-Metallic, and Organic.  What is the difference between these types of disc brake pads?

Youll run into two types of metallic pads- sintered metallic and semi-metallic. The term "metallic" without any modifier gets used for a couple of reasons- a) many manufacturers don't offer both varieties of metallic pads for a given brake, so the type is implicit, and b) lots of folks don't know the difference or think the terms are interchangeable. They are similar, but different:

Sintered metallic pads offer the best stopping power, but also cause the most rotor wear and can make the most noise, especially when wet. They are also the least affected by adverse conditions. Sintered metallic are typically used in downhill/freeride applications, but can be used for less demanding riding types as well. Depending on the setup, sintered pads can feel "grabby", that is, that they lack modulation at the lever. That problem tends to arise on more powerful brakes with larger rotors though, and both of those factors play towards that perception.

Semi-metallics are a tradeoff between braking performance and pad wear/noise. They still stop very well but can be a little less noisy and cause a little less rotor wear. They may also offer better lever modulation than sintered metallic pads. This pad type can often be found on higher end all-mountain, trail, and cross country oriented brakes, though some manufacturers opt for sintered pads while others may opt for organics.

Organic pads are the kindest to your rotors and typically quitest, but don't offer the same bite as metallic pads. These pads also wear the quickest. This does not mean that they're low end pads though, and depending on conditions, riding style and personal preference they may be a great choice. Organic pads can offer the best lever modulation of the three pad types, but may not stop riders sufficiently in demanding circumstances.


Will putting bicycle bottles in dishwasher damage them? I have been using the dishwasher for my bottles more regularly since I started using powdered drink mixes, which leave a lot of residue in my bottles that's harder to clean out by hand than when I was only using electrolytes or just water.

Will putting bicycle bottles in dishwasher damage them?  I've been noticing a distinct plastic taste on my bottles as of late.

The first step is to probably check the bottle for the icon shown below to identify that the manufacturer has said the product is Dishwasher Safe.

I just checked my bottles, and they don't contain an icon saying they are dishwasher safe, but it does thankfully have the "food safe" icon. On the manufacturer web site it says that the bottles are dishwasher safe, but to avoid using the 'sanitary clean' or 'heat boost'  settings as they may distort the plastic. It also goes on to say that the recommended way of washing them is by hand. Following the manufacturers advice is probably the best option.

Personally, I just use regular dish soap (Sunlight) and water. Once in a while I'll do the full brake down pulling off the silicone nozzle and soaking them in very hot water with some added bleach. After letting them soak for a while, I'll rinse them thoroughly and then finish off with soap and water method.

I also try to use certain bottles only for water and try to never put anything other than water in them.  Bottles that get Gatorade or similar tend to take on the taste of the drink and therefore don't work well with water.  The ones that have only water in them tend to last longer and the ones that get Gatorade are replaced more frequently.


Wheel going badly out of true on final tightening On two occasions (same wheel, loosened everything off and re-did the whole thing after the first time) as I've applied a final half turn to tighten the spokes round the wheel it's gone from being pretty laterally true (within about 0.5 mm) to badly out of true (probably a couple of mm or more out).

The simplest explanation would be that I've managed to mess up by missing spokes/over under-tightening some of them, but I'm fairly sure that's not the case.

What else could cause this?

This is a rear wheel with a fair amount of dish. I'm worried that I might be over-tightening. On both occasions I decided to do a final half turn as the non drive side seemed a little loose, but I was concerned the drive side might be over tight. Could this cause a sudden change in trueness?

I've got the wheel back to a reasonable state, but I'm no longer sure I have even tension in the spokes.

From the lack of detail in your question I'm going to assume you don't have a tensiometer. If you do, please tell us what tension you're actually using and what the limits for your rim are.

edit The "final half turn" is, as Andy points out in the comments, scary. That will give you an extra 100-200N of tension at a time when you should be working in selective 1/4 turns (ie, some spokes get tightened 1/4 turn, others get loosened 1/4 turn) or even smaller increments. It's also something that will stretch spokes (ie, they'll tighten beyond their elastic limit and become permanently deformed). You can't undo that, you have to replace the spoke as it's permanently weaker than it should be. And it's not necessarily the spoke you were turning when the problem became obvious that has stretched. A spoke giving like this will produce the minor taco problem you talk about.

Building wheels without the proper tools is hard, and you have to expect to make a lot of mistakes. Completely redoing an old wheel is harder because you have spokes that are bent and some may have deformed as well as dirty threads and nipples that may be partly seized in the rim. Much online advice says "it's easy" but is specific to small wobbles recently appearing in a reasonably new wheel. You're well past that now.

What you're trying to achieve is perfectly even tension on each side of a straight rim. To do that you either need to measure the tension or do extra work to make guessing the tension easier. There are various approaches and I'll make suggestions for each:

nipple feel. You guess the tension based on how hard it is to twist the spoke tool/nipple. For this to work you need to have clean threads and clean, even seating of the nipples in the rim. Very unlikely to work on older rims without eyelets unless you take the wheels apart and clean the nipples before oiling them and reinstalling. You can fake this to some extent using a degreaser and penetrating oil but if you also have rim brakes cleaning up afterwards is both crucial and difficult (you'll need to use a light solvent to remove the oil).
Using this method your problems above may well be caused by one or two sticky nipples that feel tight in the rim, meaning the spoke is looser than you think it is.
Spoke pinging/musical method. This can actually work, but relies on the length of the spoke section you're pinging being the same for all spokes on one side, and your sense of pitch being accurate. IME I can get a 1-2% variation by stress relieving a wheel, and 5% by pushing spokes back and forth. But I have perfect pitch so I'm excessively sensitive to changes like that. I have seen someone build a wheel this way and get nice even spoke tension. It was ~10% off the tension they wanted, but it was even and the wheel worked fine for years afterwards. Using this method your problem is that you're not getting the pitch as accurate as you need. Maybe go round and push all the spokes the same way then ping again.
Position is all. Don't worry about spoke tension, just get the rim straight. This can work, much as buying a lottery ticket can make you rich. It's just that unless you happen to have even tension when the wheel is straight it's going to go out of straight very quickly. By iteratively straightening and stress relieving you can eventually get a wheel that will stay straight for a while. The more you iterate the longer it will stay straight, as long as you keep refining how you define straight. People doing this often talk about needing to get wheels straight to better than 0.1mm. Using this method your problem is that you're missing half the picture, spoke tension is also important.

These days a Park Tensiometer (TM-1) costs about the same as the labour for two wheelbuilds. I suggest making a truing stand out of an old front fork and buying the tensiometer rather than buying a truing stand and not having a tensiometer, if you're looking at spending money.

This question is more encouraging about the pitch method and is worth a look.


Where (UK) can we rent an adult tricycle or recumbent tricycle There are a lot of cycle tracks (mostly old railway lines) in the UK that have bike rental, however very few of them have adult tricycle or recumbent tricycle.

Does anyone have the list of where you can rent an adult tricycle in the UK?

Where abouts in the UK are you?  You might want to check out the following places:

London Recumbants - http://www.londonrecumbents.co.uk/bikes_we_hire.html
DTek - don't have a web site but can be emailed on dtekhpvs@btopenworld.com
FutureCycles - futurecycles.co.uk

Hope you get sorted.


Which threaded headset size do I use? I have a frame that I want to use. It is an old early 80's Cannondale frame. How do I tell what size threaded headset to use? What diameter should the tube be?

If you have the fork in hand, it's easy enough to directly measure the outer diameter of the steerer tube using a set of calipers or a ruler across the top. The common threaded headset size is 1" (25.4mm), but 1 1/8" (28.6mm) is not unheard of.

If you have only the frame and are trying to measure from the inner diameter of the head tube, then you are measuring for the outer diameter of the headset cups. For a 1" headset this should be 30.1mm, for a 1 1/8" headset this should be 33.9mm, give or take at most 0.2mm.

1980's should be too early, but Cannondale also experimented with oversize head tubes at several points - if the fork or frame is larger than that specified for the 1 1/8" size, you'll probably want to look into a different fork, and probably a reducing headset as parts are going to be almost impossible to find.


Can I fix or replace the quick release lever on my thru axle? I've got a problem with the quick release lever on the front thru axle of the bike I use for a short commute (a several-years old Motobecane Fantom Cross Outlaw, FWIW).

The last time I tried to remove the front wheel to fix a flat, I had trouble with the lever on the thru axle. The lever would just spin, and no force was being applied to the axle itself. I fiddled with the mechanism to try to get it to engage properly, but nothing seemed to work. I even tightened (and eventually removed and re-installed) the tiny screws on the sides of the lever. Still no luck. Finally I had to use pliers to turn the axle and get it off.

Once I got the wheel off the bike, I played with the lever mechanism some more and it seemed to be working again. I put the wheel (with new tube) back on, and the lever worked fine until I'd gotten the axle just barely tight enough. Now it's refusing to engage again, and I can't either tighten the axle further or loosen it up.

Anyone have an idea as to whether this is fixable? I've already tried tightening the screws that are on either side of the lever mechanism. If it's not possible to repair, can I replace just the lever, rather than the entire axle? I'm also open to replacing the quick release lever with a setup that would require a wrench to loosen/tighten. Thanks in advance for any advice!

Anyone have an idea as to whether this is fixable?

It's not worth it.

Quick release skewers are cheap.  The medical costs you might incur if your "fixed" one were to fail while you're riding won't be - even if you have full medical coverage and no amount of medical care will cost you money, the non-monetary costs of any potential injury from a front wheel falling off while riding are potentially huge.

Buy a new one.


Cycle law: definition of Dismounting Some area requires you to dismount your bicycle. So what is the exact definition of dismounting your bicycle?

Can you just simply dismount from your bike seat, but keep one foot on the pedal to propel the bike forward?

Or do you have to completely dismount and walk the bicycle?

By definition, dismount means to get off the bicycle. That means you should not be straddling the top tube, but should be standing next to the bicycle. Then, you can walk the bike if needed. This is the safest bet, and the one you should use unless you have additional information.

You shouldn't just get off the seat and pedal with one foot or waddle, unless you have additional information that says its okay in that area.


Is vehicular cycling legal in France? I learned to ride in Toronto, where behaviour such as the following is legal:

  if there is not enough space to share the lane safely with another vehicle, it is legal to ride near the centre of the lane, so that drivers must wait or change lanes to overtake

Is this also true in France?

I asked a french man (the father of a competitive cyclist) who replied something which implied, "no": that cyclists should keep right at all times, and that although groups ride two-abreast, they return to single-file if a car approaches from behind.

I would like to double-check: is it legal, and is it at all customary or is it likely to annoy or cause aggressive driving?

Examples of when I might want to use it include:

In a town where the road is narrow or lined with parked cars
In the country-side, going up a hill with many bends, where it wouldn't IMO be safe for an overtaking car to leave their own lane (which would tempt them to overtake me without leaving much margin)

Cars routinely slow down behind tractors when they go up that hill; but when I was driving (a car) I was surprised to see a cyclist hugging the verge as if there was enough room for me to overtake him safely (I didn't think there was and so I didn't).

Also, is there any legally-required overtaking margin (for example, "cars must leave a gap of one metre (3 feet) when overtaking a cyclist")?

FWIW I understand there is strict liability law in France, which may help, nevertheless I'd like to do whatever it is I should.

The Code de la Route also states the following:

  En marche normale, tout conducteur doit maintenir son véhicule près du
  bord droit de la chaussée, autant que le lui permet l'état ou le
  profil de celle-ci.

Which means:

  In a regular situation, any driver must keep his vehicle close to the right side of the road as much as the state of the road allows it.

This part does not specify the nature of the vehicle so bicycles are impacted.

The "as much as the state of the road allows it" is a freedom breech that allows you to add good sense to this law:

ride on the right, but not too close as to be within reach of an opening door of a parked car!
ride on the right, but if the road is narrow enough that you consider overtaking by a car unsafe, prevent it from happening a ride closer to the centre!
ride on the right but if the side of the road is covered by debris, move closer to the centre!

True it might piss the drivers off but ensure your own safety first.

The police is not that picky with cyclists and when they're riding on the right half of the right lane, everyone is happy I would think.


Shouldn't use two extreme gears? I purchased a new Mountain bike a month ago and noticed after a week or so the gears were starting to slip, this was expected because of stretch in cables and wear in etc so I took it in for a tune up at the place of purchase and when I got it back the gears were still slipping in places.
I then took the bike to a local mechanic and he said that I shouldn't be using the gears on the high extremes ie the two smallest cogs at the back because of the angle of the chain. I will admit I am no expert but in all my life I have not heard this, is this true?
Thanks
Thanks to all that answered! and to add to my question to clarify some points, i have 3 chain rings on the front and the slipping sensation is more like a clunk from the front crank when i put pressure on the pedals, its not a constant noise. this happens on a flat surface so its impossible to use this gearing on an incline.
It only happens when i have the chain on the small front ring and either of the two smallest back cogs.
I also get a 'ghost' gear shift when i use the middle front chain ring and either of the two smallest back cogs.
There seems to be polarising opinions about cross chaining which i will look into but either way i think i should be able to use all my gears if i want too. yes?

Using the smallest chainring with the smallest sprocket or the largest chainring with the largest sprocket should indeed be avoided. It’s called “cross chaining”. It’s less efficient and causes slightly increased wear and noise. On the small-small combination it can cause chain slap (because the chain will be almost slack) and on the large-large combination the chain is almost taught, so getting something like a twig caught in your chain can easily cause the rear derailleur to snap.
However cross-chaining is not very bad and it should work just fine. Just avoid it if you can.
Of course if you only have a single chainring it can’t be avoided and you should just use the gears when you need them.


What does a good weld look like Reading various questions and answers around here, I've heard a lot of people say you can tell the quality of the bicycle by looking at the welds.  How do I know what a good weld looks like as opposed to a bad weld.  In this answer its stated that good bikes have smoother welds.  However, when looking at my bike, the welds don't really appear to be smooth at all, even though I know it is a high quality bike.  What should I look for when looking at the welds of a bike? Pictures would be greatly appreciated.

I found This site about welding to be somewhat helpful. There's an image near the bottom comparing a good weld to a bad weld on aluminum.  The good weld is actually the one that isn't smooth.  The type of weld used differs on the type of material used (steel vs aluminum).  A lot of the information on this site talks about coloring, so you can tell if they went too slow and burned the material, but this would often be covered up by the paint on a bike.


How do I train to gain Tony Martin/Fabian Cancellara/Bradley Wiggins esq abilities to turn over a big gear 58t, 11t,? Assuming you had access to a power meter and a heart rate monitor. What sort of training would you do?

To just turn it over for a short period?  You would just need to have above-average leg strength: the quickest way to gain this strength would just be to do leg strength exercises such as squats, leg presses, etc.  You don't need superhuman levels of leg strength merely to turn over the gear.

The hard thing is to turn it over at a good cadence, for an hour at a time.  If you don't have the cardiovascular capacity, your legs will be burning and you'll be gasping for air in short order.

To actually make use of the gear you need to have the cardiovascular capacity of be a world-class time-trialist.  The first step there is to be one of the few born with sufficient innate ability.  The second step is to do years of intense training building up your cardiovascular fitness.  After that, you would probably need to work out what your preferred cadence is at time-trial speeds.  If your cadence is slow enough to need the bigger gear, then you probably already have the leg strength needed.  If your cadence is fast enough that you don't need a big gear, then why bother?


Data to convince teenager that blinking rear light is worth the "uncool" factor I've read the topics on flashing vs. steady lights, but my question is even more basic:

Is there any data to support my contention that a flashing rear light will significantly increase the safety of a rider in the DAY time?  I know as an automobile driver I certainly see them sooner, but that's purely anecdotal.

My 14-yr-old, raised on a cul-de-sac with what I would call a "less than stellar" sense of urban traffic, naturally thinks blinky lights on the back of your bike make you a loser.  But while he is a teenager, he's smart and logical enough that if I had some convincing data on accident rates, he'd probably buy it.

Try as I might, I've been unable to find much!

After much searching for any possible statistics on flashing versus steady lights, I found none...only opinions, and lots of them! It seems people do recognize a flashing red rear light more quickly and from a greater distance away than a steady light, but as far as judging the distance to the bicycle rider the vehicle driver is, seems to be a problem for some. I use a flashing red light in the rear at all times. On cloudy overcast days and before sunset, I use a flashing white light at the front ( especially when the setting sun may be in the drivers eyes ). And of course a steady white light after sunset. Emergency vehicles have flashing lights for a purpose. You can see them coming from the front or the rear well before you may hear their siren, so the flashing lights do draw attention. Your 14 year old son will be just like other kids his age ( I know I was! ), and won't pay much attention to what you ask...until he has a "close call!" Kids his age think most drivers are about their parents ages. They don't really consider the elderly person driving down the street with 80 year old eyes or other problems, as being a danger to their activity on a bicycle. If he thinks the flashing light is "not cool", then there's a lot of flashing red light "nerds" in my area includiong me! I wish to live to ride another day, so I tend to attract as much attention to my position on the road way as possible. All you can do is "advise" and hope eventually they feel you're more right than they are. As long as he uses the rear light, that will give him more time to realize you're only looking out for his welfare.


Are there real use of the lowest bicycle speeds? I'm confused about the speeds amount in my bicycle. There are totally more than 20 different speed configuration on my bicycle, but are there any practical use of such speeds as 1-1, 1-2, 1-3, 2-1. What are that crazy places to use these speeds in real world?

Imagine, we can mount top 7 speeds of 10-speed cassette. Would it make sense to avoid slowest speeds since they are unused?

P.S.: The smallest speed i have ever used it 2-3 and that was a crazy steep uphill ride with plenty lot of small stones on it. What is your lowest speed?

You're right - there's an awful lot of overlap between the gear ratios offered.

I dunno about your riding, but I have a 21 speed (3x7) and the lowest gear is 26/28  (that's a 26 tooth front chainring with a 28 tooth big cog on the back block)  and I occasionally want one lower on the super steep climbs.

At the other end I have a 52/12 and on a downhill I am spinning out too soon.

This shows that 28/16 is about exactly the same ratio as 48/28.

You might choose to be on the big chainring if you're about to go down hill or flat and smooth, but if the next section is an uphill you would want to be in the little chainring ready for the grade.

So the middle chainring is useless?  No -  without that the front mech would have to lift the chain from the small to the big chainring, and that's a gap of 20 teeth.  Most derailleurs can cope with 13 teeth gap, not 20 teeth.

To make best use of your gears, you want to ride at a pedal cadence of ~80 RPM.  So pick a gear that lets you spin the pedals at about this speed.  Too slow and it hurts your knees.

Many riders live in the middle ring and use the rear mech to get gears, only changing front ring in the extreme of headwind/uphill or downhill/tailwind.  Personally I live in the big ring all the time, until it gets steep.

Changing gears will also help spread your overall wear, and lets you get moving quicker from a stop at the red light.

Edit: Here's a segment where 26/28 is only just sufficient:  https://www.strava.com/segments/9230838    Strava says the grade is in the upper 30's percentage, and having ridden it I'd agree.  The main problem is keeping the front wheel on the ground.


Can outer tyre (casing) punctures/cuts be fixed? My flatmate got his tyre stabbed. With a knife, it seems. (The bike was tied to a staircase railing in the building and was obviously in some maniac's way. Though there was plenty of room around. And another bike next to it.)

Is there a way to fix the cut (it's quite big, some 2 centimetres)?

EDIT:

Here are some photos: https://www.dropbox.com/sh/oulsuugvjaihta2/a3tiZm2BEp

You can "boot" the tire.  This involves placing a piece of relatively stiff material inside the tire to cover the hole.  For smaller holes a piece of US currency (which is printed on quite durable paper) is often folded several times and inserted, but 1cm is about the limit for that.

You can buy a commercial "boot" that is a piece of plastic or stiff rubber designed for this duty, but they're a bit expensive and really only intended for cyclists to carry for emergency repairs on the road.

If you can get your hands on a scrap bicycle tire you can cut a boot from that.  Generally you'd cut the piece from the sidewall, not the tread area (because the sidewall is thinner), and for a 2cm cut in a tire you'd make the boot at least 6x6 cm, and ideally as large as you can manage.

You insert the boot in the tire, maybe with a spot of tire patch glue to keep it from shifting (but make sure the glue doesn't ooze into contact with the tube and glue it in place), insert the tube, mount, and inflate.  Partially inflate first and check that the boot appears to be centered over the cut and not bulging, and that the tire is properly seated on the rim, then, when you're confident, fully inflate.

When you use a boot like this there will always be a "lump" in the tire.  And the repair is nowhere near as reliable as a "sound" tire.  But, properly done, this can be quite serviceable.


How often should I change road bike tyres? My road bike has now done 500 miles, but unlike cars, I've no idea how often the tyres should be changed. It's used on normal road conditions. The brow of the tyre is now smooth.

How do I know if my tyres need to be changed, and how long should I expect tyres to last?

How long a tire lasts depends on a number of factors, including what type of tires you ride, how much you weigh, the conditions you ride in, front vs rear tire, etc.  In general, a good set of tires will last a couple thousand miles.

When the tire is totally worn out, you can usually see threads beneath the rubber in places.  Alternatively, the tire may start to bulge in spots.  In practice, road tires rarely get to this point.  Much more commonly, they start accumulating a lot of cuts from glass and other debris in the road.  When you start getting disproportionately many flats, it's a good idea to replace the tire (you can use the tire longer, but you'll probably waste more than a new tire's cost in tubes).


Do brake cables become more elastic with time? I bought a used bike a few months ago, and I've noticed a drastic reduction in brake power.
At first, I was easily able to lock-up the rear wheel while squeezing the brake lever only half-way to the handle bar.
Now, I can squeeze the brake lever all the way to the handle bar and I'm experiencing negligible stopping power. I've shortened the brake cable at the caliper several times, and it's now as tight as I can make it without causing it to close slightly and rub the rim. Squeezing the lever slightly causes the brake to close and contact the rim, but I can continue squeezing all the way to the handle bar and still not apply any real stopping power. It feels as though the cable has become more elastic with time, like the whole rear brake system is softer to the point of being nearly useless.
Is this "normal"? Is it an indication that it's time to replace the cable? Is replacing the cable likely to make my brakes more responsive?
Update
Upon closer inspection, my brake pads are worn down to plastic-on-metal; there is no rubber left at all. This is very likely the cause for my perceived soft braking, and definitely the cause of the lack of brake power.

Cables will stretch over time, but they won't become elastic. They're made of twisted strands of metal, and metal isn't generally known for its elasticity.

This sounds to me like your brake pads are shot. When they become spongy and glazed, you can squeeze your brake lever quite far and feel like little pressure is being applied. Get thee to a bikeshoppery.


Seeking suggestion for headset and bottom bracket press I'm looking for a suggestion on a single press tool, good quality, that will allow me to press fit a Praxis PF30/BB30 conversion BB and also a headset on a nice titanium frame. A single tool would be much easier on the budget.

I've used the Park Tools BB30 tool thing and a bar clamp (eg this) to squeeze pressfit bbs in. I can't speak for headsets though.

I've found that local bike clubs are a good way of gaining access to specific tools like this. Especially as they can be expensive considering how many times you might need to use them. And you get the bonus of someone who's experienced fitting things like headsets before. People are usually keen to help a fellow cyclist out.


Is there an (un)official rule about twisting back a seat on broken bike for CitiBike or other shared bike programs? "don't pick a bike if its seat is twisted around backwards. That's a sign that a previous rider found the bike busted." -(from SamtheBrand's answer to How to choose the right Citi Bike? )

Can someone please elaborate on this rule please?

Is it widely known and used?[1]

Is this some sort of official or unofficial rule communicated somewhere?

Is it specific to Citi Bike program or generic to any bike rental/sharing ones?

[1] - I have ridden Citibikes almost every weekday for over a month in NYC, and have never observed a twisted-around seat. But I didn't set out to find one so it's not much of an evidence.

This appears to be a widely-used, but unofficial way of communicating that the bike is broken and should not be ridden. See the Wired article that documents this trend: "Courteous Citi Bike Riders Are Alerting Others to Broken Rides" by Christina Boddington.

Also, on Twitter, you can find numerous examples (many of which were cited in the Wired post).


Do I need a spacer between my cassette and freehub? I am fitting a modern Shimano 10-speed Hyperglide cassette (CS-HG81-10) to an old Shimano 8 speed hub (FH-M565). Fortunately, it is long enough (approx. 35mm) to take 10-speed.

The hub came with a spacer and I am not sure if I should use it or not. I know that when fitting 9/10 speed to an 11 speed hub you should use a spacer, but I am going up from 8 to 10!

The spacer measures 1mm. I can fit all sprockets with and without the spacer, however with the spacer the final sprocket will extend slightly over the end of the hub.

How do I know if I need a spacer or not?

My guess is that the spacer is for fitting 7 speed cassettes (which are narrower than 8-10 speed cassettes).

Try installing the cassette without the spacer, if you can tighten the lock ring up and it isn't bottoming out on the freehub, I think you are good.


Cyclocross on airplane I'm planning on flying to Japan for a bicycle vacation early this spring. Having had a look at flight bags, I'm puzzled. They are expensive, weigh tons and are huge, I couldn't feasibly bring them with me on my bicycle trek. I might be able to rent storage for roughly a month in Tokyo, but it seems like quite a tedious project on its own.

How do the rest of you manage? Remove the wheels and wrap the thing up in (EDIT: cardboard and) plastic-wrap on the airport, have it checked in instead of luggage, and then use the panniers as carry-on luggage? Is it safe? Has anyone had their bicycle damaged or stolen during transport?

For packing, a box from a bike shop will do fine and you can chuck it in the recycling when you get to Tokyo and find another before flying out. Most bike shops will give these to you if you ask nicely and even if they charge you, it ain't going to be much.

A much bigger issue is airline choice. Options for flying with a bike range from free to pay by the kilo in excess charges to some obscene special bike charge. Read up and check the baggage allowances for sporting goods very carefully.

If you fly a lot, get a loyalty card, the extra 10kg you get on most airlines' lowest tier covers a bike in a box nicely. And if you get some special luggage tags, that can't hurt either.

My bike has survived a few flights totally unharmed, this was in a bike box though. Though I do have friends who have shipped a lot of bikes all over the place in cardboard and I've never heard of any problems. Not that it can't happen, it's just unlikely. You can't move for bikes/bike shops in Tokyo so getting spares isn't going to be an issue.

Getting your bike stolen is not going to happen. Walking out of the secure side of an airport with a bike up your jumper is going to raise eyebrows.


Is rubber cement in stationery stores the same as in tire patch kits? Is the rubber cement that you can buy at the stationery shop:

the same as what's in the little tubes of cement that come with your patch kit:

If not, then exactly what is different? What makes tire patches stick much more strongly?

The "cement" used in tire tube patch kits (de)vulcanizes the rubber in the patch and of the tube. Which is a chemical process, usually using sulfur, where the rubbers bond and form a stronger bond than just an adhesive would do.

Rubber cement is just a gooey adhesive. Usually latex with acetone and other chemicals to make it more pliant. You wouldn't want to use it to patch a tube since it is not very strong, will degrade the integrity of the surrounding rubber and patch, and in general make a mess.


How can I tell if my bike can ride down stairs without damaging it? I would like to know if my bike can handle going down a flight of about 15 stairs. (edit: ride it down, not jump)

Specifically I have a Merida Crossway 100 . However, I would like to know if there is a general rule of thumb that I can use for my future bikes.

Just to clarify:

The stairs in question are 13 x 30 cm each.
I realize that technique is also involved, but whereas bones can heal, wheels cannot.

There's no real way to be completely sure but to try it. Anything else is merely a guess and no one can be 100% sure of the answer: suppose there's a tiny crack somewhere no-one knows of and it just happens to receive enough stress while riding the stairs then you might get damage. But such things are impossible to predict.

Moreover there are many other factors to consider but you don't specify any of those. What kind of stairs? 15 stairs where each step is 1.5m deep and 5cm high (yes that exists, architects invent all kinds of things) is like riding down 15 seperate tiny curbs with hardly any impact. But 15 stairs with steps of 20cm deep and 15cm high is already something else. Still, you don't specify how you plan to ride them nor what your skills are. If you ride them fast, lifting the front wheel so you barely touch them, most impact will be when landing them, on the back wheel. Which might or might not break, depending on rim/spoke/build quality. Or you could ride them very slow like going 1km/h while constantly braking and gently rolling down eacht step so there's hardly any impact at all. I wouldn't expect any damage there but you need some balance skills for that. Or you could just ride down at a speed of 20km/h both wheels at the same time. Then the geometry of the stairs vs the geometry of your bike plays a role in how gentle the ride will be. If you're lucky each wheel happens to land on each step 'nose' exactly and you won't even notice it's stairs as it will be like riding down a normal slope. If you're out of luck (usually, in my experience) it will be rougher. I'd still advise you to lift the front wheel to clear the the last couple of steps as it makes for a softer landing back to flat.

tldr; there's more to consider than just the bike

  is there a general rule of thumb that I can use for my future bikes

No hard rule, but: if the bike is rated for terrain which roughly matches the stairs you're aiming for, then it should handle those stairs. A 10000$ downhill machine should be able to deal with any 15 stairs with no problem as it's made to deal which much stronger impacts. I wouldn't take a 200$ BSO down stairs though.

Your particular bike seems to be some hybrid targetting 'cross' whatever that may be, but it doesn't exactly seem to be targetting rougher terrain. I don't have any experience with the brand nor quality so I have no idea how solid it is. From the looks and specs, and if it's in good conditions I'd take the risk and ride it down the stairs no problem but that's just me, don't take my word for it. Or maybe try with stairs of like 5 steps first: should there be damage, it will be less. As said before: ultimately the only way to know for sure is to try it.


Chains for fixed gear bike noise problem I mounted my fixed gear bike and I would like your opinion about the installation of my chain.
The noise in the following video is made by my chain (and nothing else) and I am not reassured.
I first thought the run of the chain was not correct but yet it seems it does.
I checked that my chain can move vertically more than +/- 0.5 inch (halfway).
Here are my components (they are all new):

Surly steamroller frame
chain 1/2 x 1/8
miche Bottom bracket 107mm
miche primato adavanced drive

Here is the video, how does it sound ?

At first I thought the chain was rubbing on the wheel, if its a new chain then it might not have been greased. Don't use wd40 if its not greased, it will wear it faster. Try White Lightning.


Change 700c rim to 650c I've bought a road bike for my wife. The bike size is 45cm or XXS. The problem is, the frame is high for my wife. Can I change the rim from 700c to 650 to reduce the problem? For info, my wife height is 155cm and her inseam is 68cm.

Changing to a smaller wheel may cause other problems, such as needing brakes with a longer reach (that won't work as well), or the bottom bracket is lowered, so the pedals may ground around corners.
This bike is super small already - the fundamental problem is, as you have guessed, the wheel size, which governs the dimensions of the frame.
I would be looking at a bike with 26" wheels, or even 24" - they generally didn't make road bikes with these wheels, so you might need to adapt a mountain bike or a kids bike. It is quite possible to put road bars and gears on these frames.


Short stem & riser bars on XC I found a crack under my handlebar and I'm thinking of buying a riser bar and a shorter stem for my mountain bike. is it a good idea? I don't ride on trails, not because i don't want to, I just don't have the chance to.Is it necessary to buy a riser bar & a short stem on a XC hardtail?

Not sure if it's necessary but here is a picture of my bike I found on the internet.

Generally you can use any stem and bar you like, as long as they have the correct clamping diameters.

Be aware that you might need longer or shorter brake and shifter cables.

As a sidenote: I think often when people have the impression that there is too much weight on their hands it’s actually because their saddles are too low or in the wrong position. With a proper seating position roughly a third of your weight is on your hands, butt and feet each. With more intense riding it can be more than half your weight on your feet (this is one of the reasons why pro riders can ride such low bars and hard saddles).


Quick question about V-Brakes? I'm interested in purchasing a bike, however due to my location can't get into a bike shop, so will need to order it online.

The 2009 GT 2.0 Transeo I am interested in does not explicitly say it has v-brakes. I know it is not the disk version though.

The 2010 GT 2.0 Transeo mentions it has v-brakes.

Is the v-brake a fairly recent improvement in rim brakes as recent as 2010?
I know it is common for people to assume disk brakes are better. But I'm trying to bring down the price of my purchase, and do not intend to go cycling on rough mountain paths, or do too much wet/muddy condition cycling. Which is better in your opinion for my usage?

Thanks in advance.

The 2009 edition will have 'V' brakes, although they may be called 'cantilevers' or something else that describes roughly the same thing. This is base specification for an MTB, to be assumed unless stated otherwise.

Disk brakes are better in the wet because the braking surface stays nice and dry, however, you can still stop in the wet with V brakes. We have already had this question:

Why are disc brakes rare on road bikes?


What size are shimano MTB (wheel) hub ball bearings? I wish to replace the Ball bearings in my Shimano hubs. What is the standard sizing for MTB?

Rear hubs are generally quarter inch (9 per side, so 18) and front are generally 3/16 inch (10 per side, so 20). Obviously, if you're going to do this, order extras.

See this crib sheet from Sheldon Brown.


Shimano Revo shifter does not shift I have recently bought a new bicycle and the left Shimano Revo shifter (3 speed) is not shifting, what can I do?

To really know what is wrong we need more information. But to give you some help:

If you don't know how to re-adjust the gear to shift correctly:
- Clean the derailleur (which pushes your chain to another gear).
- Push the cable back and forth a bit, and if possible, oil it a bit.
If this didn't work and you don't know how to adjust your gears to work correctly, bring it to a bicycle mechanic (such as me!). Because you can't do much more without disassembling the cable.

If you do know how to re-adjust the gear, this works better:
- Disassemble the cable.
- Clean the derailleur, and put some grease on the spring.
- Take out the inner cable, and spray a lot of oil in the outer cable
- Assemble the cable inside the outer cable. Check if the shifter works correctly by pulling the cable and shifting.
- Assemble it al again.

edit: it took me 2 edit's to correctly write 'inside'!


Chain slipping on middle chainring I have recently replaced the chain and the cassette. Previous chain never slipped. I never had any problems with it at all. But I have made about 10 000 km on it and the wear was beyound any limits, so friends and guys in the bike service recommended replacing both chain and the cassette. I did a lot of reading and I know that chain and the cassette wear together.

So I got chain and the cassette replaced. It is a 9 speed cassette. I have asked to replace it with a little lower gear ratio. Guys in the workshop also indexed the derailleur for me.

Since I collected my bike the chain slips terribly every time I stand up on the pedals. Sometimes it also slips when I apply enough pressure even while seated. But standing up is a definite slip. I already have few bruises from falling down on the frame.

I had assumption about chain being too long, but is seems to be just about ok.

I have also figured out that the chain never slips if it is on the lowest or the highest chainring. It only happens with the middle chainring. As I have said before - it never happened before with the old chain/cassette. Now I have tried to stand up and pedal very hard in all gears on low and high chainrings. Never got a single slip in about half an hour of trying. Changed back to the middle chainring - it slips in every gear from 1 to 9 when enough torque is applied.

So the question is: can it be that chain is slipping at the chainring? Do chains ever slip at the chainring at all? I have never heard of anything like that. Is there a simple way to test it in order to be sure that the chainring is the root cause?

I really don't want to blame it on the chainring and get it replaced just to figure out that the problem never went away.

I expect that after 10,000 km your chainring also needs to be replaced (frankly, I find it astonishing that you made it that far without replacing anything else.  That's amazing.).  Am I correct in guessing that you spend most of your time in your middle chainring?  If so, it will be significantly more worn than your large or small rings, which would explain why you're only experiencing slippage in that ring.

It should be very easy to tell if it needs to be replaced--either take it to your shop and have them look at it, or look at it yourself.  Worn chainrings will show a characteristic "shark fin" on the teeth if they're worn too badly.


How to repair a broken steel frame, at the rear drop out /chainstay location I have a Raleigh technium , recently broke at the rear dropout. Angelo had a post w a picture of a broken rear dropout and commented, that this failure on a steel frame was totally repairable, btw...Would really like to fix mine!

Apparently Raleight Techniums are weird combination of aluminum and steel. Rear triangle of Techniums are steel (chro-moly, I'd wager) so they should be repairable.

Looking at the pictures of Technium rear dropouts, they seem to be cast pieces that are brazed to the rear triangle. If the joint between the dropout and seat/chain stay is broken, then the fix is matter of re-brazing the dropout. If the dropout itself has cracked, then it needs to be welded together.

In either case, you need to take the frame to shop that can handle frame repairs. To do it yourself, you'd need a workshop and either TIG welding machine or oxy-acetylene torch and brazing materials. Not a job to the faint hearted.

Full disclosure: I'm a amateur frame maker. I've made couple of lugged frames and fixed a broken frame by welding it, so I have some idea what I'm talking about.


optimum frame size for very small 5'2" female I have a lady friend who's interested in getting into road cycling. The smallest frame sizes I've seen so far in the market are 48 and, in one instance, a 47. Is this about the most common and/or smallest starting point for frames for these riders? She's average weight (around 100lbs). Any recommendations on frame size would be appreciated.

My wife is 5' 2" and raced elite road for many years.  For her proportions 48-49 cm frames seemed to work well.  Sometime she had mentioned interest  in a smaller frame, but when I looked at how she fit on the bike I think it was due to flexibility issues (at that time) rather than frame sizing issues.

Of course this is one person's experience and therefore not a canonical answer. There are a lot of factors, other than frame size, that govern fit, but 48/49cm is likely a good starting point for someone 5'2".

NOTE: different brands will have slightly different fit dimensions (stack and reach) for the same quoted frame size. Frame sizing is  not standardized.


Super tight brakes don't work My son is at an age where I could be buying him a new bike each year because he is growing, but instead I managed to pick up a free bike from someone who put it out for trash collection.

Only problem is the brake pads were worn to the end.

I have replaced the brake cable, tried two different sets of different brand brake pads and tightened everything until it can't be tightened anymore.

You can see from the pics that the brake pads are right up against the rims, but those @&$@#%s just don't stop the bike.

The pictures show the pads right up against the rims when the brakes aren't even engaged.

The only thing I can think is the rims. Any suggestions?

Reading the comments I am going to presume the problem lies with the rim/pad interface not generating enough friction rather than pressure from the brake lever getting to the pad/rim interface.

First step - Presume the rim is contaminated with something slippery. Clean the rim presuming its either oil or silicon based. Use an degreaser/solvent first to attack an oil based contamination, the use an abrasive cleaner and scrub well with a steel wool or aggregative nylon scrubber and plenty of soapy water to remove non-oil based contaminants. Don't worry too much about damaging the rim - if you can't get the brakes working do you want you son riding on it?

Now the pads - presume these, even if new, have been contaminated by the rims. Ideally buy new ones (Come to that later), second best and worth a try is to clean them with degreaser, soapy water then file or sand the top layer off.

Assemble them with a bit of toe in (front of pad hits rim first). Put them together. (Look here for good instructions). Now the brakes need to bed in. Go for a ride, and give them a dozen of so max effort stops from high speed (careful you don't do anything silly)

Couple of points: Are the pads good quality one like Koolstop?  Cheap pads are often made of hard compound, take a long time to bed in and have low friction.  If possible, get softer pads with more grip (and shorter life). The brakes are calliper brakes typical of road bikes, that offer poorer braking compared to V brakes and discs. Better callipers may help, but they do have a limit of how good they can get.


Why are emergency inflation cartridges filled with CO2? Why aren't they filled with ambient air using air compressors? Isn't compressing ambient air cheaper than generating CO2? If it is, then those cartridges would have two benefits:

Cheaper to manufacture
CO2 filled tires deflate on their own far quicker than ambient air, so using air will mean, once you inflate your tire with a cartridge, you will not have to inflate it again when you are back home.

CO2 charger cartridges are used for bike tire inflation because they are a common, inexpensive product that has been around since the 1950s. Their other uses include powering air guns and inflating life vests.

They were originally developed by the Crosman Corporation and marketed under the name "Powerlet".

Powerlet cartridges are filled with CO2 presumably because it's the most suitable gas. Reasons I can think of are:

CO2 turns into a liquid at relatively low pressure compare to other gases -
liquids are much denser than gasses so a useful amount of CO2 can fit in a small container.
Containers are easy and cheap to make to withstand the required pressure
CO2 is cheap and easy to make (although probably not very environmentally friendly).
CO2 is inert, will not react with the container material. It isn't flammable but heating a cartridge probably isn't a good idea.

Updates to my answer seeing as it popped back up on the main page for some reason.

CO2 cartridges are not filled with compressed CO2, they are filled with liquid CO2. That has to be done to get enough of the stuff in the cartridge to be useful. The cartridge is not completely filled however, and the gas pressure in the space is essentially constant (the vapor pressure) as long as there is some liquid CO2 remaining.

You can't put liquid air in a cartridge because it's comprised of nitrogen, oxygen, water vapor and CO2, all of which have different boiling points. In fact, C02 turns to a solid before nitrogen turns to a liquid.


Truvativ Crank housing Im repairing a friends bike and changing the crank. I have removed it and want to find a replacement

The removed item is Model: BB-06-PSPL - 113/68
Im wondering if there is a replacement Shimano model? or an upgraded part available as the bike is quite old.?

His bike is running Shimano Tiagra triple crank 9 speed. I am wondering if I could change the crank over to shimano aswell or would this not be possible due to the fittings in the crank housing.?

Thanks for you time in advanced

RD

The item you removed (BB-06-PSPL - 113/68) is the bottom bracket. The 113/68 means that it s 113mm spindle length and 68mm bottom bracket length this means that it is a standard size and will be easily replaced. The PSPL means that it has a Powerspline interface with the cranks, this is a Truvativ/ SRAM proprietry system so if you wish to keep the cranks you are using you would need a replacement Truvativ cartridge.

If you are willing to change the crankset as well you are not limited in any way as long as:

The bottom bracket is 68mm and English thread and has the same interface as your new crankset, or you could choose and external bearing set up.
The crankset is built for the right drive train, if you have a 9 speed rear derailleur you need a 9 speed crankset as chain widths are different.
You can achieve the same chain line as your current set up with a new crankset through selecting the right spindle length.  (this may take a few internet searches for Shimano this is available in the Tech Docs for each crankset).


Long bar ends as drop-downs? There's a pair of long bar ends that I came across on Decathlon (https://www.decathlon.in/p/4407859/cycle-handlebars-stems-and-grips/3-position-long-bar-ends). I was wondering if these could be rotated 180 degrees (from upright position) to convert them into drop down bars or maybe tilt them by 90 degrees to make an extended aero flat bar? Can it work?

Yes - this is a known way to get stubby aerobars on a flatbar MTB, that don't stick out too far but provide some benefits of an aero position.
Downside is that you generally can't have brake levers, so your hands are a long  way from the brakes. This is definitely not for urban riding of any sort.
Likewise, you're further from the gear shifters.  Okay if you settle into a gear and stay there for a while, but not good in undulating roads.
Lastly remember that since your hands are closer together, there's less fine-control.  So to start with it will feel very squirrely, and crosswinds can have a much larger effect before you can recover.  Over-compensating is possible too.
Upshot: this is great if you have a long open road in your commute on a MTB, or if you have a gravel fire trail/track.

Normally these "Bar Mids" (instead of Bar Ends) would be attached to the bar inboard of your grips, brakes, and shifters.  So all that has to come off the bars first.
If you do races on this bike, remember that many disallow the use of bar ends, so bar mids might be disallowed in the event.


Repair superficial damage to a carbon frame I have a carbon frame with an integrated seatpost. The saddle sits on a clamp that is meant to secure the saddle on the seatpost and NOT hold the weight of the rider too. I went on a ride and my knees started to bother me, so I went to adjust the height of the saddle and after reading the torque number for the binder clamp, realized I was shit out of luck and was going to either raise the saddle and risk damaging the carbon fiber or let it be and hurt my knees more.  I of course chose to raise my saddle. So now I have some nasty gouges where the clamp rubbed the length of the seatpost.

I have spacers in place now to raise the saddle to the correct height but now I have some ugly scratches that are visible just below the binder clamp.

So, the question is, what should I use to keep the surface carbon from cracking more and to seal it up?  I have been told to use either paint(not sure what kind) and to use a clear nail polish. Thoughts?

I have repaired non structural and surface carbon blemishes with clear nail polish. I had no issues and used the handle bars for several years with no issues.


Can I fit a 26x3.5 tire on a 26x4.0 rim? i have a sondors bike that comes with a 4.0 fat tire. i am tring to find a street tire for my fat boy i only found one and its 3.5 not 4.0 STREET TIRE

A 26"x3.5 tire should work on any narrow 4" fat bike rim.  That is: 60mm-70mm wide rims.  It might work on an 80mm rim depending on the actual width of the tire. But will definitely not work on a 5" fat bike rim which is 100mm wide.

Surly does not recommend their Black Floyd (listed at 26"x3.8" but actually narrower) road tire for rims wider than 65mm, for comparison.

I tried to find the actual specs for a the rims on a Sondors Fat eBike, but it looks like there are a couple versions.  One comes with 59mm rims, which should work for a smaller tire.  However, the other version (with the 4.9" tires) might have a rim that is too wide for those tires.

The Apache Fatslick http://veetireco.com/listings/fat-tire-apache-fatty-slick/ is the only option I know of a "road" tire for a 5" rim.


Can you shift both the front and back gears simultanously? Is it advisable to shift both the front and back gear simultaneously? Can this cause any damage?

There's nothing wrong with doing this. It works well to shift the rear 1 or 2 shorter when shifting the front 1 taller (and vice versa) to avoid big steps in gearing.


Bike pump: what is this lump? What is this lump in the picture and how does it work?

I have another pump, which physically is the same but minus the bulge.  The one in the picture seems to perform better, ie less work to reach the same pressure.

This from an old article circa 1996 it references a Medai floor pump. "Screwed into the base near the compression tube is an air tight steel chamber. This chamber is known as a reservoir and holds a volume of the compressed air to assist in equalizing the pressure of the pumps compression chamber and the inner tube. This feature gives the tire a small assist in time as it "seats" on the rim."


Standing on cottered crank scuffs bearings? I have single speed road bike, with cottered crank and my caged bearings wear out too often, could it be due to me standing on the crank (like elliptical trainer) pretty often e.g. when i need to go up the hill or accelerate fast?
Would replacing caged bearings with loose bearings make it withstand more load?

My experience in general with bearings (Wheel hubs mostly, and some bottom brackets) is that if they wear out too quickly in spite of being well lubricated and adjusted is either the ball bearings are poor quality or the races and cones are already damaged, or both.
Substituting caged balls with free balls allows for somewhat longer maintenance periods but not much (1.5x longer aprox).
When the races and cones are pitted, corroded, or deformed they wear the balls faster.
The other factor is that the bearing must be correctly pre-loaded (that is, the cones correctly tightening the balls against the races).
The only times I messed around with bottom brackets It has been square taper axles, and was having a similar issue as the one you described. At the time I used a low quality bike and the only replacements available locally where low quality parts. At first I thought the cups where unscrewing themselves, but took note of their position and no movement was apparent. However the axle developed play in about six months of about 4 days per week use, around 2-3 hours. (teenager, riding up and down small paved hills).
At first I tried using only the balls, without the cage, using as many balls as they would fit without the cage. But then I noticed the cups had small holes in the race (the channel where the balls roll) and also, the "cone" part of the axle had a "groove" made by using the worn balls too much.
The solution was to replace all the parts (cup set, axle and bearings)
My adjustment was to tighten the cups all the way until I felt resistance when trying to rotate the axle by hand, then receeding a quarter of a turn, then tighten the locknut. I had to try a few times until I got it right. (No play on the axle was perceivable by hand when forcing the crank arms, slight resistance to rotation due to the grease)
That was the last setup that I performed on that part of the bike and it where good for at least a year, when I "grew up" to MTB and got a new, better bike.
I would argue that standing on the cranks should not wear then any faster, at least if they are well adjusted and in good condition. On the other hand, using them while out of adjustment definitely makes them wear faster. (I had a bad experience with a cheap bottom bracket cartridge. It developed play but kept using it for commuting daily. After a month or two, the cartridge failed catastrophically leaving me unable to pedal and in the middle of a street right after an intersection)
Just for reference: here is an image showing the terminology I use. Please excuse me if the labeling is not correct.


Internal friction in new Alfine 11 S7001-11 I just bought a new rear wheel with an Alfine S7001-11 internal-gear hub. Before installing it, I realized that it apparently has heavy internal friction. When the wheel is set in motion, it comes to a halt again after only a few seconds.
Since I have mostly used bikes with derailleur systems in recent years, I'm not sure if this level of friction is "normal" with internal-gear hubs, or if I received a damaged hub.
For an illustration of the issue, find a video with a comparison of the new wheel with the Alfine hub and my old one with a derailleur system via https://photos.app.goo.gl/5m6GG9HRmzLCeUyS9
Is the hub malfunctioning?

Summary: You should not expect this hub to spin like a well adjusted gearless hub. Make sure that the hub is lubricated and adjusted correctly (assuming it's not broken) and whatever drag is left is normal.

In addition to the drag from the gears and roller clutches, there may be drag from the bearing seals. Drag from the large bearing seal on the right side is highest when coasting, or in the lowest and highest gears, which are farther away from unity ratio.

Sheldon Brown on the Alfine 11
The question then becomes - How much resistance is too much?
The key to this is to adjust the hub correctly.

Place finger and thumb over the lock nut so that they are touching the hub, move the wheel rim up and down and feel for a slight bit of play through your thumb. If none is detected back of the cone until it is. Then by small increments turn back the cone and nip the lock nut until the play is almost undetectable then tighten the lock nut. Note: an over-tight cone can cause creaking when cycling, excessive play will strain the mechanism.

Cycling IK Forum - "Shimano Alfine 11 - Longer term reliability"
According to the Shimano manual - page 78 (there are pictures)

Screw the left hand cone to
adjust so that the hub shell can
be turned smoothly without any
play. After adjusting, secure the
stop nut with the locknut.

The manual also details how to add oil or change the oil in this hub.