New Shimano m615 rear caliper fails and stops biting the rotor after 30 seconds of extreme downhill I never had this problem with my Hayes stroker trail. It only seems to start working after I stop for a minute or two. I am riding 30% grades so a lot of force for the short time period, then the brake softens up to the point where it loses 90% of the braking ability, and I can only use my front.

It's easy to determine that you're obviously losing your braking power due to heat generation. But hard to pin down exactly what's wrong without actually looking at your bike. There are a couple of things that could be going on, which could be a result of a mechanical issue, or an operational issue.

Mechanical Issue

First of all, your m615 brakes are only middle of the line, they aren't intended for extreme downhill (check out the Saint line), but even still, 30 seconds isn't a very long time before failure. There are a number of questions I would ask you in the shop;

Has this always been a problem, or is it something new?
How long have you been riding these brakes?
When was the last time you changed your pads?
When was the last time you had your system bled? and Did you use Shimano oil?

I would also inspect your bike, check what size rotors you're using and look for any obvious signs of oil leaks. I'd check the wear of your brake pads, and use a micrometer to check the wear on your rotors. I would look at the colour of your rotors, if they're blue then you've cooked them and they need to be replaced (Bluing steel makes it harder, harder steel means less friction–ergo–less stopping power). If nothing was visually obvious then I would bleed your brakes to check the condition of the oil, and make sure there isn't any air in the system.

Shimano Brakes use mineral oil, which is different than the DOT brake oil that would go in your Hayes brakes. Different oils have different boiling points, DOT oil is regulated (DOT 3, DOT 4, DOT 5.1-The higher numbers reaching higher boiling points) But Mineral oil is not regulated, which is why it's recommended to use the manufacturers oil. Some shops use bulk mineral oil made for other applications because it's cheaper to buy (Shimano oil is expensive), but it may not necessarily have a high enough boiling point. If your oil isn't pink, then it's either dead, or not from Shimano.

Opperational Issue

This is the part where I grill people about how they ride. Improper riding habits are a mechanics bread and butter, I've replaced more parts from riders causing damage to them than from parts wearing out due to normal use. One of the bluest pair of rotors I've ever seen came off of a bike whose rider was probably a good 250lbs and rode about 10km back down a trail–that was ALL downhill–riding his back brake the whole way. You have two brakes for a reason, and the FRONT brake is the one with all the stopping power. When riding extreme DH, your back brake is for steering, your front is the one that stops you. You need to use them together when you need a lot of braking.

I gave my big friend with the blue rotors a long lesson in proper braking, then installed a new 8' rotor on his rear wheel and a big 9' rotor on his front. He never had brake problems again. It's important to make sure you have a braking system that can handle you and what you ride, if you're  bigger guy, then you're going to need bigger brakes, if you like to ride fast and steep, then again, you're going to need bigger brakes.

If bleeding your brakes or swapping out brake parts is a bit beyond you, then you need to take your bike to your local shop, they'll be able to tell you exactly what's going on, and may recommend you upgrade your brakes or your rotors. The alternative is to slow it down and ride gentler grades.


Cant get my rear derailleur to reach all cogs I have been having an issue on my road bike getting the rear derailleur to reach all of my cogs.  I can either not reach my two smallest cogs or two largest cogs depending on the cable tension.

I found a nice set of instructions here: http://www.williambenedict.com/bikes/derailleurs.html and followed through them with the cable disconnected and I was able to set the limit screws so that if I moved the derailleur manually I was able to shift smoothly to every cog.  Once I connected the cable I was able to shift to all but the 2 largest cogs so I started adjusting the barrel 1/4 turn at a time.  I had to turn the barrel almost all of the way in order to get to the 2nd largest cog(I can't even reach the largest) and with this adjustment I can no longer reach the two smallest cogs.

From what I can tell my derailleur isn't bent at all.  Also, I'm not sure if it is much more difficult to shift to a larger cog than it is going back to a lower (I have bar end shifters).  I have to pull on it quite hard.

Since I am able to successfully shift to every gear smoothly whilst manually moving the derailleur, I imagine this is an issue with my cable.  Would it's age have anything to do with it?

As you suggested, the cable may be at fault.  I change my gear cables once or twice a year to keep shifting smooth and free. If the cable/cable housing are old and worn they could be offering resistance.  If that resistance is too high the springs in the derailleur may not be strong enough to pull the cable through.

Try removing the cable and housing, then make sure the derailleur and shifter are moving freely before fitting the new cable.

Then replace the cable and housing (these are cheap to buy online, but you do need a pair of housing cutters to cut the cable housing - think mine cost be about £15).


What is this bike model and year? Cannondale CAAD? I have an opportunity to buy this bike for $200 and was wondering what model and year the bike is? From one of the pictures I see CAAD and on another, I see seven, but I'm coming up empty handed when googling. The owner says he bought it last year.

Thanks!
Mike

Cannondale Quick 7: https://www.cannondale.com/en/USA/Bike/ProductDetail?Id=7adbe241-cc33-4ea5-b62f-9f32c8476f31

Not sure of the year; you can look up previous years and see if the color scheme is different, or if the components match what was spec'd on that year (derailleur, shifters, number of gears, etc.).

It's a fairly entry level hybrid from a major company, so bikes like these don't go huge overhauls very often -- it doesn't look much different than the 2018 visually aside from the black crankset in the figure below.

Image from Cannondale.com


Is it worth swapping two front-wheel hubs? I have an old Bontrager Select rim with cartridge bearings and a newer Syncros Race 27 with loose ball bearings.

Both are 20 spoke, would it be worth it to swap the hubs? Or would it even be possible?

"Worth it" is opinion-based, but no, probably not.

Possible, yes, but it's more technical than it might appear, and much more complex than building normal wheels, because the Bontrager wheel in the pic has paired spokes and the other does not. Normal hubs have spoke holes on the two flanges that are interleaved evenly with one another, to match the evenly spaced holes on the rim. Hubs for paired spokes have holes on one flange staggered a certain amount ahead of the other, also to match the holes in the rim. That's why your radial paired spoke wheel has spokes that still all radiate outward from the center of the hub.

If you were to do what you propose with these two hubs, you wouldn't be able to use the standard spoke length calculation formula. You'd have to do some measuring/math and rework the formula for the unusual spoke/hub angles that would result from doing this. You'd then be left with double-grooved hubs because the spokes wouldn't fall along the same path as original on either, which is never a good thing but should be avoided at all costs on radial wheels, because it sometimes makes the flanges blow up.

(Also, if it's not obvious, even if not for the issue of one being paired spoke, you'd still only physically be able to swap just the hubs and re-use the spokes if the hubs were close enough to the same dimensions, which they may or may not be, and that's putting aside all cautions against re-using spokes.)


How much maximum force can be applied by fingers on the brake lever? I am trying to calculate maximum force various braking systems can apply and for that I need the ergonomic data as to how much force fingers can apply.

If your question is about the maximum hand grip can applied to brake so that the braking system will not be broken apart, then it is as another answer.

However it has little value on designing a braking system.

How I interpret the question is: how much force is typically applied to the brake lever to stop the bike.

There are many designing considerations and I only list a few main one:

Maximum force on to lever that a person feels comfortable at gripping for a long duration (for me it's about 5-7 kg or 50-70N)
Modulation how well the spread between the the force at which the bike starts to decelerate, and the Maximum force. This depends on the braking technology, the pad/rim surface/rotor. But in general, disc brake is superior because of the (more) linearity in braking.
Linearity: how linear the stopping power versus the force applied by brakes? This is interesting and thus somehow explains why road bike is equipped with caliper, hybrid with cantilever, and mountain bike with disc brake. Linearity improves as we go from caliper-cantilever-disc. The discrepancy is large when higher stopping power is required. But at smaller (required) stopping power, a caliper is not that much different front disc brake for a given braking range.
Maximum stopping power This is safety feature, but it should not be easy to flip the bike with too little gripping onto the brake lever. This has to take into account the bicycle geometry, and that is why road bike is normally equipped with caliper brake. Even some (supposed-to-be) road bike has disc brake, the rotor/leverage/cylinder was designed so that it has much less stopping power than a mountain bike disc brake.

Well, it depends on type of brake and how fast you would like to stop the bike, at what speed, and at what momentum.

If you just want a number to work with (for your home work?), I can give you.
A normal cable brake on flat handle bar would need about 40-50 N (3-4 kg) for hard stop, about 20-40N (1-2 kg) for normal deceleration.

Same stopping power with drop handlebar and caliper brake would need about 1.5 to 2 times as much (comparing Figure 1 and 2), depends on hand position (leverage). Typically hands at hood position requires more force for same stopping power in comparison to hands at drop position.

Same stopping power with hydraulic disc brake needs about 0.5-0.7 fold. This depends on the rotor size/pattern and type of ceramic and thus it is hard to quantify. But the general still holds, if you are designing a disc brake that has an enormous stopping power for normal stopping, you actually degrades the modulation ability of said brake.

Figure 1a. Normal barking force on drop position of drop handlebar

Figure 1b. Braking force required to lever on emergency stop on drop position of drop handlebar

Figure 2a Braking force required onto lever in cantilever brake for normal stop

Figure 2b Braking force required onto lever in cantilever brake for hard stop


Can't downshift rear derailleur I'm trying to fix my wife's bicycle which sat out all winter.  I can't get the rear derailleur to downshift from the twist grip shifter.  I have inspected and cleaned and lubricated the cables, nothing is frayed or stuck.  I can move the derailleur with my thumb quite easily, and if I hold it I can move the shifter.  I can also upshift, but I can't get the derailleur to downshift from the shifter.  Any ideas?  It's a Shimano system.

I solved a similar problem by dousing the inside of the shifter liberally with WD40 and leaving it overnight, I mean really soak it until it's dripping. I had to do this twice but the shifting was perfect afterwards.


Is there a cable-stop variant for the screw-in internal routing ports? On my frame the internal routing "ports", the things that are screwed into the frame with a small hex-head screw, have ingress/egress holes large enough for cable housing to pass through it.  Is there a variant of these screw-ins that has a cable-stop, so bare cable could be used?  A bare cable would be easier to install and a handful of small cable donuts would keep things quiet. Do these things have a name?

They aren't universal in any way. Depending on the bike/brand, there may be some out there that fit the same frame hole and do what you suggest in the case of a manufacturer trying to employ the tactic of re-using the same small parts, but that's not how it usually is.
Some frames are set up to allow a straight shot of cable like you suggest, but usually it would have that sort of housing stop if so. Running bare cables in a frame set up for continuous housing is generally not something that can work.


Could a road bike be used for cyclocross? So i have a cyclocross bike, but most of my friends have road bikes. I am interested if people think that a road bike could be used to race cyclocross.

I'm thinking that with a pair of nobbly tires it might work.

EDIT: This is a just thought experiment. I have a CX bike which i use for road in the summer and cross in the winter.

Depends on your road bike, but for the most part no.

Reasons against

Many road bikes are limited to tire width of 25 or 28mm.  Because cycle cross is off-road you need to find tires with knobbies. This really isn't possible for such small tire sizes as most knobby tires available start at around 32mm or large. Even if you could find knobby tires this small, The tight tolerance between the tire and the brake caliper will mean any mud would clog and slow the wheel from moving.  Finally, most rode bikes have a much lower bottom bracket and twitcher handling. The lower bottom bracket will mean a lot a pedal strikes especially on off camber sections and the faster steering will make this type of road bikes harder to hold a line in rough sections. Cyclocross bikes also tend to have lower gearing, a much slacker front geometry and longer wheel base so that the bike hold the line better. The higher BB not only reduces pedal strikes but also makes it easier to initiate change in directions by shifting weight, despite the slower steering.

Reasons for

Some road bikes slacker geometries and more tire clearance (e.g.,older, endurance and adventure road). I had one steel bike that could clear 35 mm tires, this one could have been used on dry courses. The bottom bracket will still be too low and the handling likely a little too twitchy, but these would be much more suitable than what most manufacturers  currently sell as race road bikes at the moment.

Note that many cyclocross series do not follow UCI regulations and are happy to let you race whatever bike you bring.


Is it really safer to ride in the road than on the sidewalk? I am fairly new to riding, in a city where it is legal to ride in the road or on the sidewalk. In the areas where I need to ride, the roads are busy but the sidewalks are virtually deserted.

I keep hearing that it is safer to ride in the road, but is it really? Are there studies that show (or contradict) this?

It seems like the hazards of riding on the sidewalk are things that are under my control (don't zoom through crosswalks, watch out for cars coming in/out of driveways), while the hazards of riding in the road (people texting while driving, cars passing too close, road rage) I have to rely on other people being careful.

So it seems to me that I am better off riding on the sidewalk where my safety is in my own hands than in the road where my safety is in the hands of all of the drivers around me. But I am new, so I acknowledge there may be other aspects of this that I haven't thought about... so is it really still better for me to ride in the road, and if so, why?

Edit to add: This is a small city in the midwerstern United States. The sidewalks I am talking about are on stretches of road where it's mostly businesses with large parking lots, so there won't be any kids playing or anyone backing out into the road (but still will be people turning from the driveway to the road or the road to the driveway). With the exception of right by a bus stop, you almost never see pedestrians on the sidewalks, it mostly seems to be bicyclists. As an alternative to riding on the sidewalk of this road, I could take a more indirect/winding path through some neighborhoods where it wouldn't feel quite as scary riding in the road and ride in the road there - but is that really any safer than riding on the sidewalk near the busier roads?

In most scenarios, it is not safer for you to ride on the sidewalk. This has been demonstrated numerous times in numerous studies. I won't attempt to site individual studies here, but I will sum up the reasons.

One is that you create more potential points of impact. When you exit the sidewalk to go through an intersection, driveway, or parking lot entrance/exit you are in danger from the cross traffic as well as parallel traffic making turns. The latter danger is greatly reduced if you ride in the street simply because you are in the same lane as those drivers.

Furthermore, drivers simply aren't watching for cyclists on the sidewalk. Cyclists typically move much more quickly than pedestrians and drivers aren't prepared for that. Cyclists seem to "come out of nowhere" as compared to slow moving pedestrians. Pedestrians are also able to stop much more quickly if a driver doesn't see them.

All that said, there are some situations where cycling on the sidewalk is safer. Personally, if the speed limit is under 40 mph, I typically ride in the street. If it's over 50 mph, I typically ride on the sidewalk. If it's between 40 and 50 mph, I judge the road based on how many entrances and exits there are, how wide the shoulder is, how much traffic there is, etc.

Mike Baranczak said it beautifully in his comment, "Riding on the sidewalk is always a bad idea. But sometimes riding on the road is a worse idea. You have to decide based on individual circumstances."


Which direction should axle lock nuts face? After having my bike worked on recently at the LBS I noticed that my rear axle lock nuts are arranged so that the smooth/flat sides are contacting the dropouts. To clarify, I'm discussing the lock nuts that go outside the cones, not the axle/track nuts that secure everything to the frame.
I removed the wheel and loosened the lock nuts for the sake of some photos.

From observing photos of other people's axles, it seems like the rough/beveled/textured/grooved/serrated edge should face away from the center/wheel and towards the outside/frame. The opposite of how mine are installed.
As far as I can tell from my research, this is the common orientation. Rough side faces out, smooth side faces in.
             <rough|smooth]             [smooth|rough>

[etc] [frame] [lock nut] [etc. hub stuff] [lock nut] [frame] [etc]

The photos I've found all seem to imply the rough side touching the dropouts is the right way to do it, but I can't find any conclusive results for bike axle nut which way or bike axle nut which direction.
Is that a general rule for axle lock nuts that the rough side should always face the dropouts?

The rough side should face the frame dropout.
The roughness is designed to increase friction with the frame dropouts. This type of knurling works because the frame dropouts are un-hardened, either low-allow steel or aluminum. On the other hand the knurled washer is probably hardened (or at least harder) steel. Thus the knurling can 'bite' into the softer frame steel and increase friction.
The rough side facing against the other axle parts serves no purpose. Not only is the extra friction against the hub parts un-needed, but axle hardware like bearing races is often hardened, and such knurling will not work against other hardened parts.
That said, the knurling itself is unlikely to be critical for the function of the bike. If the axles are done up correctly, there will be plenty of friction even without the knurling against the frame. So I think it was assembled wrong, it shouldn't cause a problem.


Recovery after long ride I biked the longest I have in my life; my previous record was one 12 mile ride, but today I went ~36 miles on my MTB. Should there be any steps I take to recover myself? Also what things should I inspect on the MTB? I noticed that during my ride there was sometimes pain in my lower back ... should I be moving the seat forward or backward?

You cannot draw any conclusions from one ride. Especially when your have ridden triple the distance of your previous longest ride. Anyone would expect some discomfort in that situation.

Regarding recovery, it should have started during the ride. By this I mean you should have made sure you ate periodically and drank frequently. Some things that can help recovery

a massage by a sport masseur
catching up on fluids
a good meal
a good sleep
a recovery ride
stretches before your muscles cool completely
and (I previously omitted) a cool-down period before you stop exercising.
also, sports compression garments (especially shorts in this case) will help your muscles recover.


Prescription eye glasses and shoulder checks I've never had prescription glasses but might like some.

My left eye doesn't focus easily (I ride on the right side of the road, in Canada). If I look over my left shoulder, I can see behind me only using my left eye (the field of my right eye is obscured by my nose). It's hard to see what's moving towards me and how fast, at a glance using one eye, because the edge-detection is blurred.

So I think I want driving glasses which:

Let me focus towards infinity (that'll be the optometrist's job)
Great peripheral vision: so I look through the lens even when looking sideways (i.e. behind)
Other: clear, polarised, rain/snow-resistant, durable.

Can you tell me anything about this? Lens materials, frame styles (with specific examples), or anything else?

My answer is based on 25+ years of wearing prescription glasses and contacts.

For road cycling, fitness cycling and sometimes commuting, I wear contacts plus non-prescription cycling glasses with interchangeable lenses. The lenses on the cycling glasses are clear, plus 3 different tints and densities for varying light conditions. The lens coatings are key. I personally insist on scratch resistance, anti-glare coating and you can also find lenses with anti-fog coatings and UV protection. The higher end cycling glasses usually have these types of coatings on the lenses.
For commuting and casual riding, I usually just wear my normal prescription glasses. Your optometrist will determine your prescription, but you can specify various coatings and even the option of variable tints. Anti-scratch coatings and anti-reflection coatings are a MUST in my book. Anti-fog and UV coatings are nice but it's up to you. For the frames, most optometrists have many options and I'm sure they can help you make a decision based on your needs. You'll want to look for a sturdy frame if you'll be clipping a mirror onto the frame.

Depending on how old you are, you may need to consider progressive bi-focals. Anyway, I've never had any issues with peripheral vison, but if it's an issue for  you just talk with your optometrist about it.

Here's a link to a description of the various coatings. Personally, I can't live without anti-reflection and scratch resistant coatings.

You might check out this link as well: What are the features that I should seek in cycling glasses?

A note on cycling specific glasses... Most higher end cycling glasses (Rudy Project, Bolle, Oakley, etc) have the option of getting lenses with your prescription. However this is a very expensive option, especially since you'll need to replace the lenses when your prescription changes. This is why I use contacts with my non-prescription cycling glasses, because contacts are cheap.

@ChrisW - After seeing your comment... I think I'd recommend cycling glasses with Rx polychromatic lenses. Cycling glasses + interchangeable lenses + contacts is probably overkill for you. The quality brands of cycling glasses usually have that kind of option. I have Rudy Project glasses and before that I had Bolle, both of which are available with Rx lenses.


Maximum weight of a pedal vehicle I can't seem to find a straight (approximate) answer to this question.

What is the maximum weight of a pedal vehicle (cargo bike, rickshaw etc) an average person can drive at a decent speed, say 15-20 km/h?

According to Bikes At Work:

  Our experience has been that most people can comfortably pull 300 lbs (137 kg) with a typical mountain bike and cargo trailer or cargo trike. How quickly a person can move load of that weight will depend on his or her physical condition. Someone in reasonable physical condition can generally pull a 300 lb load at 10 mph (16 km/hr) on level ground if there's no wind. A person exerting the same effort could pull a load of 600 lb. (275 kg) at a speed of about 8 mph (11-13 km/hr), and a 1000 lb load at about 6 mph.

At the page linked above there is a calculator:

  to estimate how much weight a typical healthy individual could transport on a warm day in still air using a bike and trailer or cargo trike. Things like wind speed, equipment condition, and personal health can have an enormous impact on results, so use this only for rough approximations.

Bikes At Work is talking about a bike pulling a cargo trailer but the information can be extended to other pedaled vehicles.

Once you get a weight moving on the flat you can move a lot of weight - given the right gearing given a reasonable level of fitness. Hills are a whole other world.


Does anyone make a dynamo light buffer battery that will keep it going at full power? I have a nice SP dynamo hub and an old Supernova E3 Triple dyanamo light. However, the dynamo light isn't very bright when I'm starting my ride, as my ride has a long hill at the very start, so I don't go very fast. Then it's a lot of stop and go riding for the rest of my commute with a few more small hills. The standlight kind of sucks until I've been riding on a straight stretch for a while. Looking forward, I would consider buying new gear to help, but I'm not sure what I need (other than just only using battery powered lighting).

Basically, I want my bike to always have lights on while I'm riding through the winter months where I'm commuting both to and from work in the dark, and not loose lighting when I'm stopped or going slow on a climb (where I'm very venerable). Currently, I have to supplement having dynamo lighting with battery powered lights since the dynamo lights cut in and out due to my hilly commute with lots of stop and go urban riding.

Does anyone make an inline power buffer for dynamo based lights to provide (a) Immediate on when you want to start riding and (b) Constant power while stopped? Or are there lights or other equipment that provide this feature (without forcing me to build my own circuit boards and such)

There are standlights, which are essentially supercapacitors combined with LED headlights. They're designed to be charged from the dynamo while riding and give you a few minutes of extra lighting when stopped at a stoplight. However, all the ones I know will self-dissipate after a while, so they're useless for your purposes of starting off the day with full beam strength (unless you want to bike around on the flats for a few minutes charging them).

For full strength lighting at any time, you really need a battery.

I don't know of any commercial battery-charged dynolights. I built my own circuit that takes the AC from the dynamo, rectifies it, uses the DC to charge an 18650 that then powers my LED headlights and taillights (and charges my cellphone). The circuitry is trivial by itself, but you'd have to know enough about soldering small circuitboards and I can't do any customer support, so I haven't shared it.

The reason I built the rig was that I wanted more powerful LED night lighting (10+ watts) than my dynamo could reasonably deliver at one time. So I charge my 18650 by riding during the day; and then at night, I have instant full power.

My assumption is that if you know enough about electronics to solder it, you should know enough to design it. All parts are available from sparkfun in terms of rectification and smoothing, lithium batter charger, battery, switch, LED current limiter, breadboard, and so forth.


Hire road bike for one day for race (never ridden one before)? So I am thinking of doing a triathlon in a couple of months. I've been training on a hybrid bike and have only ever ridden either hybrid or MTB.

Your probably thinking, don't do it you're mad, totally different riding position, much narrower tires etc.

So what do you think? I would have an evening with the hired road bike the day before the race, do you think I can literally jump on a road bike for the first time and for a race and pull it off or am I kidding myself?

In your first tri , you’ll have all sorts of new things to concentrate on, I don’t think an unusual bike should be one of them.

When I’ve seen people ride road bikes for the first time, it’s the gear shifting that’s often trickier and more distracting than anything else. I’ve seen people take more than one ride to get the muscle memory to change gear in the direction they intended. It becomes intuitive, but through practise.

For your first tri you’re also only racing against yourself. So if you know how fast you normally ride in training, you can compare how fast you race, and know if you’ve done a good job on race day.

If, afterwards, you want to do a second triathlon, put the rental fee you save towards a road bike to train and race on.


What are the brake housing stoppers on the end of the brake housing called (see pic) My brake cable snapped while riding my (80s road) bike one day so I replaced it.

After replacing I noticed that the piece fixing the housing to the brake was missing so that when I pulled the brake lever the housing comes too and it doesn't move the brake.

My questions: what is this piece called, and is it something I can buy separately, Is it something that comes with brake line housings, or is it part of the brake lever itself?

They're essentially part of the brake lever. They don't really have an agreed-upon name. Probably the closest is "mushroom ferrule," which appears to be what Dia-Compe calls them.

They're not totally universally sized. Different brake levers have slightly different bits that go there but do the same thing. That said, the ones on the great majority of bikes with applicable levers are all the same size, which I believe is basically Dia-Compe and clones.

You can just buy the common size ones new. In the US, J&B Importers (one of the largest parts wholesalers) has a house brand one they call a "Cable End Button" and UBS has one they call "UNIV BRAKE CABLE ADAPTER." There's also Dia-Compe part 94, same thing. You can just order any of them from an online reseller, or find a shop that has them. Some shops will also have old levers around to cannibalize.


Why is there a distinction between friction and indexed derailleurs? I've seen people make a distinction between a derailleur being for friction or indexed.

Is this distinction somehow functional? I can't see how it could be, because every derailleur I've ever seen just takes a movement in the cable and translates it into a movement in the cage.

With the possible exception of the newer electromechanical shifting systems, the derailleurs themselves are not "indexed"; they move within a range according to the cable movement. The shifters control the cable movement, and are the thing that are indexed — not the derailleurs.

Most likely what people are referring to is whether the derailleurs are part of a part of a group that uses indexed shifting. But assuming the same high-low range, take-up capacity (for a rear derailleur) and cable pull ratio, a derailleur that was originally part of a friction-shifting group should be interchangeable with an indexed shifting group and vice-versa.


measure dropout to fit chain tug I want to buy a chain tensioner, like the one in the first picture in this answer.

I did some research and it looks like they have different size, according to what they call "dropout size". In fact, 5mm and 8mm seem to be the two most popular sizes.

What does this measure refer to? How should I measure my frame to be sure that I buy the right chain tug?

There are two dimensions that matter:

Axle diameter. 10mm is the standard, but you'll also find models designed for 9.5mm (3/8") and 14mm axles on BMX bikes.
Dropout thickness. This is the thickness of the metal plate comprising the dropout when looked at end-on. The tensioner cups the ends of the dropout, so must be large enough to fit over them. Steel dropouts are typically 5mm thick, while aluminum frames can have 8mm thick dropouts.

In both cases, you can use a caliper to determine the dimensions precisely, but a simple measuring tape or ruler should be sufficient.


Chain fell between cassette and spokes, what to replace? My chain fell between the cassette and the spokes while riding, and it destroyed my rear wheel. I know I'll have to replace the wheel, but can I keep the cassette and the chain? There is no visible damage on either.

Yes - I've suffered the same event when the chain jumps over the cassette and you keep pedalling.

In my case I kept trying to pedal, and the chain chewed into about 9 spokes right at the elbow.  I probably damaged the chain a bit too.  Surprisingly, the cassette seemed OK.

The fix options

replace the rear wheel - this is the most expensive, but gives you peace of mind and a warranty.   I couldn't afford this.
replace the damaged spokes.  Spokes are between $1 and $3 unless you have weird ones.  You will need a "spoke nipple tool" and whatever tool is needed to remove your cassette/freewheel from the hub of the wheel.  Simply replace the most-damaged spokes one at a time, duplicating the under/over pattern.  Once they're replaced, use the nipple tool to true the wheel.
do nothing and wait for the spokes to break.  Depending on the level of damage you might be able to ride fine for a long time as-is.

The prevention

The chain jumped over the largest cog on your cassette.  This is because the low limit screw is not set right on the rear derailleur, and it allowed the chain to go too far.

Its highly possible your RD was "plinking" into the spokes as well, which is very close to catching a spoke with the RD and then its all badness.

The other prevention is to use a Spoke Protector, which is a clip-on ring that sits between the cassette and the spokes.

Normally made from clear plastic on new bikes, they were steel or aluminium on older bikes.  Old plastic ones go brittle and then crack and fall off.  These are also known as dork disks and while they do their job, they also offer a large flat area to side winds.

There's nothing wrong with fitting one - should be about as much as a spoke or two, available from your LBS.


What is the stopping force of your average road bike? Does anyone have any data on the stopping force of a modern road bike? IE when a road biker slams on the brakes the force applied to the ground is x.xxx Newtons (or lbf).

Another way to ask would be if anyone has any speed vs stopping distance vs rider weight data for road bikes.

TO CLARIFY : I'm asking if anyone has a data set of numbers, I'm fully capable of going out and testing my own bike and doing the physics / math to obtain the information I need, but I'd just rather not do the testing. I would expect some deviation based on the kind of brakes and rims involved, but I would expect any modern road bike to have similar stopping force.

Beck Forensics have figures (pdf), peaking at about 0.5g for a MTB on flat concrete. I used this search to find that paper and some of the other results look relevant.

The number that springs to my mind is 0.3g, but that may be for cars. Bicycling Science or Human Power are where I would go for well-researched answers. Human Power doesn't seem to have anything, although it may just be missing from the index.

A great deal depends on the geometry of the bicycle, since that's the limiting factor (most bikes can throw the rider by overenthusiastic braking). A little thought experiment might help. Assume the CoG of the rider is in the hips, so about 10cm above the seat. A line from there through the front contact patch will be roughly 45 degrees above horizontal (give or take, say 15 degrees), so an upper limit of 1g is likely.

To further Feynman it, 10m/s is 36km/hr, so 1g would stop you from 36km/hr in one second. During which time you'd travel about 1/2at^2 or 5m (I cheated by making t=1). One simple test would therefore to sprint to 35kph then hit the brakes at a marked point and see what your stopping distance is.

On reflection, 1G or 10m/s/s sounds more plausible as an upper limit.


How do I replace road bike hoods? I commute daily on a road bike with Shimano Tiagra STI shifter/brake levers. The rubber hoods are pretty grimy and getting sticky, torn up and unpleasant these days. Repair and replacement of pretty much everything on my bike seems very straight-forward, but I can't figure out if these parts can even be replaced, much less how to do it. Ideas?

Easiest thing to do is just cut off the old hood then take the new hood and thread it on over the bottom of the brake lever. Some are 'ergo' and have a right and left hood so make sure that you watch for right and left hoods.


Desirable maximum steering angle Zero means going straight, 90+ degrees is probably impossible.

So what is the maximum steering angle needed to ride safely?

This is complicated, because bikes steer by turning the fork and by leaning. At very low speeds, we steer mostly by turning, not leaning.

Wikipedia gives the formula for figuring this out, although you need to transpose some terms, you need to know the bike's dimensions, and you need to decide the radius of your turn.

Based on that formula, and assuming a bike with a head angle of 72°, a wheelbase of 1000 mm, and a desired turning radius of 5 meters, you get about 37°. A longer wheelbase will increase that angle slightly; a steeper head angle will increase that angle more; a tighter turning radius will increase it yet again.


avoiding punctures in 22mm tires I used to get a lot of punctures on my 22mm tires riding to work every day in boston. All of the punctures were from small pieces glass.

After a few weeks of almost weekly flats i got tuffy tire liners and now i no longer get flats.

Question:

Is there some other better solution then tire liners because they were really difficult to put in?

Some tire makers have a thicker center. Specialized Armadillo based tires will work wonders. They are a bit heavier, but worth it.

Specialized Armadillo Tires

Im sure there are others, but this is the one I have used the most on my commuter road bike.


Help Me Identify My Bike Serial No. : HZ100202418 Hi please help me identify my bicycle, which has serial number HZ100202418.

Here's a picture of the head-tube badge, but I don't think it's original

tl;dr its a modern bike inspired by workman bikes of the 1950s.

Mayam is/was a bicycle company in Nagoya Japan, and was related to "Nittei Industry Co"  They were known for their "heavy duty carrier bicycles" which is where the double top-tube comes from.

 1970s advert.

Older advert reproduced in a calendar.

 Japanese "Guarantee Medal"  associating the names Mayam and Nittei

More info  http://chikutakurinrin.cocolog-nifty.com/blog/2011/08/index.html

Your bike appears to be a modern reproduction "inspired-by" the older models.  Reasons:

The fork has nowhere near as much rake as the old bikes.
Dual pivot front rim brake
No rear brake - loaded bikes take some stopping, though a coaster brake might work.
No carrier, nor lugs to fit a carrier
No mudguard mounts either.  A workman's bike gets used in the rain and wet.
Super short head tube.  Back then head tubes were longer - short ones increased stresses on the head tube/top/downtube weld areas.  Also related to load carrying limits
Deeper section wheels - these bikes would have had steel box section rims for strength while carrying loads.

Other - Not sure whats up with that bottle cage - might be some special modern thing that interfaces with a special bottle.


Why so many headset spacers on some expedition bicycles? I've been looking at expedition bikes and I've noticed on some bikes I've seen that they have a lot of headset spacers such as http://www.oxfordbikeworks.co.uk/models/overview/ and thorn cycles in particular. Why is that?

Having received an answer from Oxford:

  As regards spacers, cycle tourists want/need a low stand over height,
  so that their bikes handle nicely and so that they can stop easily and
  grip their bike between their thighs when fully loaded. However, many
  cycle tourists want a head-up relatively high front end so that they
  can see into the middle distance without getting a stiff neck. For
  those cyclists who come from a road/700c background, they typically
  want a lower handlebar setting at the front, so the number of spacers
  is less, so generally its not an issue.


How to determine which size spoke wrench I should buy? I was advised to use a dedicated spoke wrench (not multitool) when possible, so I am looking to order one online. How can I determine which size I need before ordering it?

I do have a multitool with spoke wrenches. They are labelled 0,1,2,3. 0 does not fit. 1 fits, but it is not quite snug. Based on Wikipedia, I assume this means that I need the 3.30 mm one. Is this correct?
For the sake of making the question more general, it would be nice to also have answers explaining how to choose the right size if one does not already have such a multitool.

No this may not be correct.
The Wikipedia sizes (0, 1, 2, 3) are Park Tool specific sizes. Park Tool SW-1 is 3.30mm. Whether or not your multitool uses the same numbering as Park Tool is anyone's guess.
My understanding is that DT Swiss nipples all use 3.23mm (Park Tool SW-0, black tool). Of course your bicycle may have some other nipples than DT Swiss.
If building a wheel from scratch, I suggest choosing DT Swiss Pro Head nipples (they have a spherical seat as opposed to the cheaper but unfortunately more common conical seat), and remembering to grease the threads of the spokes well. Then the only spoke wrench size you need is 3.23mm.
To determine what spoke wrench size you need for an existing bicycle, invest in a caliper or a micrometer screw gauge.


What kind of pump/attachment do I need for this? (picture) I am having trouble identifying what tools I need to pump these tires.

We bought some kind of kit that came with multiple attachments and none of them worked. Wondering if something is missing?

All I've ever used before is a presta valve so I am not too well versed in this stuff. Thanks for your help!

This is a regular Schrader valve like you will find on many car tires.
Your pump (if it is a bike pump) should have something to pump this up.

If in doubt, head to your local service station and try their car pump.
Alternatively, hit up a bike store, they should be able to get air in that for you!


Can you identify this "BSB 400" steel frame? I was given quite a nice old tourer some years ago. I think it was a custom-built frame. The only identification is "BSB 400" in a 1980s typeface:

It's Reynolds 531, has cantilever bosses and 130mm rear drop-out spacing.

It's an extremely pleasant bike to ride, and I have stripped it down to have the frame repainted.

Any ideas who built it or where it came from?

Mine has cantilever brakes, however I've seen another with callipers.

It is apparently a hand-made frame by Bell Street Bikes, London.

http://www.retrobike.co.uk/forum/viewtopic.php?f=1&t=184850&start=490#p2234953

  It all started back in '87 when I worked in Bell Street Bikes NW1 after school building bikes like the BSB400 touring bike and the BSB Blazer ATB which was a 531 frame with TA chainset, Dia Compe brakes and Suntour index gears, this sold for £400.

I also found a comment on a Guardian article from 2011:

  Geoff [the builder of the bike] passed away last year. Complications of leukaemia finally took him, even though he had battled it twice. A great guy, a funny man and someone who cared for other people. I used to work with him at Bell Street Bikes and it was one of the happiest periods of my life.

I'm very pleased to have to have learned more about it. I inherited it from a friend of a friend, who also died from cancer.

It has always been "Gary's bike" to me, even though I never met Gary. It's a lovely bike that I have spent many happy hours riding. Here it is half-way up a Spanish mountain (it's the one with yellow panniers):

My plan is to have it resprayed and rebuilt.


How to deal with anxiety caused by dangerous riding conditions stemming from poor lane design and inconsiderate fellow road users? Location is Belgium.

I stopped seriously riding my bike about 5 years ago. At the time, I used my bike for commuting to work for about 9 km one way. The main reason I stopped was because the timing and route of my commute brought me through various situations that I did not enjoy at all:

My home is within 100 meters of a high school, and during my morning commute, I had to drive on a bidirectional bike lane which leads to this school. However, I rode away from the school right during the rush of students riding to the school. These students often drove side by side on this lane, while there was only barely enough room to comfortably pass each other on the lane. There were multiple times where I skimmed the shrubbery on the right side of the lane very closely, almost to the point of crashing into it.
Midway through the commute, I had to drive on another bidirectional path with barely enough room for comfortable passing of oncoming traffic. However, in this case the non-street side was a foot deep open sewer with a lot of overgrowth on the other side. There were some places which had regular growths of hogweed at roughly handle height. Hogweed, for those unaware, is a plant that can cause inflammatory reactions if it comes into contact with the skin. The street side wasn't much better: there were a lot of parked cars, some parked so close to the lane that at times I had to swerve to avoid running into a side mirror. In addition, the lane was VERY poorly lit at night and even somehow had a sign partially obstructing it about halfway through. To top it all off, in order to get on this lane, I had to go through a bike tunnel under an elevated highway and take a 90° turn left, both sides of the bike lane obscured by the sides of the tunnel.
About 500 meters before I arrived at work, I get to another bidirectional bike lane. this one was short, but it was a VERY curvy path where you can't go fast, it's again barely big enough for 2 bikes to pass each other, you can't see around corners because of a 2 meter high hedge on both sides and it's quite busy. I again had a few incidents with skimming or even landing in the hedge on the side because I had to evade an oncoming biker I didn't see coming.
Along the entire path, there were a couple times I had to cross intersections with no traffic lights, some of them quite busy. I had 2 incidents at one of these intersections, one of which severe enough that my back wheel got bent out of shape and I had to bring my bike in for repairs.
Finally, a lot of cyclists along this way were really driving quite dangerously. I've already mentioned the teenage cyclists driving side by side on a lane that isn't wide enough for that, but there are others: cyclists who don't use a light at night (though I sometimes made this mistake too) or actually a blindingly bright light; cyclists overtaking other cyclists on busy lanes; Cyclists that drive too close to the center of the lane to safely pass them; cyclists that are using their phone while cycling and aren't paying attention; Cyclists that cycle very slowly in a lane where you can't safely overtake them; Even people walking their dogs on the bicycle lane.

All of this and more at the time really gave me a whole lot of anxiety about cycling, in addition to the higher amount of stress I was already experiencing from working a day job that fit poorly with my autism. I already wasn't too keen on cycling and running into these problems on a daily basis really caused me panic, stress, anxiety and so on, to the point that almost exactly 5 years ago, I gave up on riding my bike to work and switched to public transport. Since then I only rode my bike recreationally, and even then only incidentally.

I don't plan on cycling again in the foreseeable future, but if I were to one day start cycling again, what can I do to reduce the chance that I run into these issues again?

1 Avoid obstacles
There's not too much you can do about this. That school almost next to your home means you'll always be stuck in student-rush hour no matter what you do. Except maybe if you can go around the school area in a relatively small detour. Cycling on a quiet parallel road may be well worth the extra few 100 meters.
2 Be noticeable
Wear high visibility clothing (fluo vests, reflectors, clear lights when it's dark). Especially useful when the other cyclist isn't visible. At least they'll clearly SEE YOU and will evade you.
3 Loud bell
Get yourself a nice loud bicycle bell. One that you can hear from a couple houses away. Use that bell any time there's someone blocking your path, and use it early. Don't wait till you're right behind them. If you ring your bell early they should have just enough time to look behind them, see you and move out of the way when you reach them.
This one works really well if there's someone walking their dog. Given enough time they'll move their dog besides them and maybe force it to sit down, or at least in a position where they can safely keep the dog away from traffic. You might still have to slow down a bit to safely pass them.

Someone riding middle of the bike trail? -> ring your bell
2 people riding side by side not leaving room for you to pass? -> ring your bell
pedestrian not really looking taking up too much space? -> ring your bell
someone driving unsafe with cell phone that you can't pass -> ring your bell

Moreover ringing before a turn with no visibility is the only way to make your presence known without a mirror or stopping. (This is actually the main and intended use of car horns in a lot of countries)
Most of the times (sadly not 100%) they'll make room for you to pass safely when they hear a loud bell ringing.
4 Plan for slowdowns
You mentioned autism. A lot of your anxiety might come from not being able to ride at your expected pace to deal with those "unsafe" situations. If you plan on slowing down at least 10 times during your ride, some of those close to a standstill, and leave enough time to arrive at your destination in time it might take most of that anxiety away. (Note: I don't have autism myself and have only a bit of experience with coworkers/family members on the spectrum, not sure if this hint really works for you).
5 Get used to cycling in calm situations first
Instead of forcing yourself on a fixed hour to get to work in time. Try going to a grocery store in the weekend on a bike to get some minor supplies. You can plan this small trip on a slow hour when you know there'll be few obstacles. If you can't get used to the short bike trips that way, you're probably better of using public transport instead.
Final note
Although most people on this stack will likely not agree with this statement I still think it's true for certain people:

There's nothing wrong with not riding a bike.

I have an uncle that never learned to ride a bike. He always got everywhere he needed and is happy that way. If you don't like riding your bike then don't ride your bike. Public transport in Belgium is usually good enough (although not optimal) to commute to work and even do grocery shopping or visit family members.


How do i know which wheels will fit my bike? my bike is: https://www.giant-bicycles.com/au/xtc-27dot5-2-2014 and everything I have came with the bike, only now the axle of the rear wheel bent and the skewer has lost its grooves.

and I would like to replace the rear wheel with the 12 x 142mm version of:
http://www.chainreactioncycles.com/au/en/easton-ea70-xl-mtb-rear-wheel/rp-

I want to reuse the old casettes and disc break. I was told to buy new rotor bolts, will these do? http://www.chainreactioncycles.com/au/en/hope-steel-disc-rotor-bolts/rp-prod9950

Will I be able to migrate all my previous parts onto this new wheel and will the wheel fit onto my bike?

update:
A replacement axle would be prefered. What axle would work for my bike?

Unless the Oz version is different from the US version (which it doesn't seem to be; the picture is the same), it looks like this bike uses a by default regular old 135x5 mm quick release, so the wheel needs a quick release compatible hub (not a thru axle hub).

Have you tried servicing the existing wheel? QR skewers and new axles are way cheaper than a new wheel (but of course, thru axles are stronger, so the upgrade may be worth it anyway).

Edit: It looks like Giant has a conversion kit you can buy to go to 142 x 12 thru axles wheels.

A picture of the kit is here:

Looks like the two pieces on the left screw into both places where the skewer passes through, then the hanger is replaced as well. You can see this video on how to install it.

It also looks like you need a particular thru axle specifically from Giant due to threading; it looks like its a re-badged DT Swiss thru axle, so maybe they have something compatible.


Lost power when chain is not lubricated properly Does anybody know how much power is lost when the chain is not lubricated properly? I drive a rather heavy bike and experienced that when the chain is not lubricated it definitely has an effect. Can anyone give an estimate in percentages about the amount of power lost due to a non-lubricated chain.

New, factory-lubed chains have about 7W of losses at 250W power:

https://www.ceramicspeed.com/en/sport/inside/test-data-reports/chain-efficiency-vs-run-time/

Looking at their other tests with various other loads it seems to be a relatively constant ~3% of losses independent of the input power. In their chain lube test even the worst lubricant only has 9W of losses and the best has 3.8W.

As Daniel pointed out in the comments, how much higher the losses of your rusty chain are depends on how bad the situation is. I’d be less concerned about efficiency and more about longevity. It sucks to have to replace a chain every 800km just because you never lubed it. In fact, longevity is probably directly related to efficiency and friction. So if your unlubed chain lasts only 1000km instead of 3000km its friction is probably three times as high.


Grand Canyon AL SL frame size - S vs M Checked Grand Canyon frame sizes and can't decide which one is more suitable for me: S or M. My height is 170cm while S frame recommended height is 162-172cm and M is 172-182cm. S frame comes with 27.5" tyres but I want 29" which comes with M. What would you recommend?

It's going to depend on your preferred riding position and on the ratio of your torso to leg length. Without being able to test ride, it's very hard to know for sure. If you like feeling a bit more stretched out horizontally then go for the M. If you like a bit more upright compact sitting position, then probably the S.


Converting 3x7 to a 1x7. Is it possible with only existing parts? I own a 2000 model Specialized Ground Control full suspension. The front derailleur is rusty and temperamental so my solution is to remove it as well as 2 chain rings (they are removable on mine) and convert to a 1x7. This bike is not worth high spendings on upgrades so would this work if I just bought a 1x drivetrain specific chain ring and kept everything else stock? Better yet would it even work on the current middle size chain ring with maybe a chain guide attached to keep it held on? If spacers are required that's all good. I am only a novice MTB rider and the bike will predominantly be used for downhill and small jumps, no hectic double blacks or anything. I am aware that 1x7 isn't very versatile but it will be plenty for me to have fun.

You have a zero cost solution, which is to keep the front derailleur but remove the cable (and shifter if you like). Then use the FD limit screws to fix it in the right position to act as a chain guide.

You don't need a 1x chainring, in fact using one with a 7 speed chain is probably less than ideal, so you're actually better off sticking with an existing chainring. You may not be able to get rid of the big chainring, or you may need to get shorter chainring bolts if you do, depending on how the big and middle rings are mounted.


Pedal sometimes getting stuck Back story

During this weekend we went on a trip with rented bikes, and observed the following problem on one of them: the left pedal would sometimes not spin on the shaft (i.e. it remained in the same position, no matter, how the shaft was turned, whereas the normal functioning would be that it is always "horizontal", i.e. it changes its angle relative to the shaft, when the shaft moves -- so that you can keep your foot horizontal too). This is of course very unpleasant and could be even dangerous. (The pedal could be made to spin, by applying much more force on it than normally.)
As I said, the problem was intermittent: sometimes the pedal was spinning normally, then it would get stuck for sometime, then it would get unstuck and spin again, without any apparent reason.

We could not find a way to remove (and then put back) the pedal either, but I'm not sure it would have helped (we also thought of lubricating it, but did not do it in the end).

Questions

How are pedals attached and spinning on the shaft?

  |        |
 /_  _  _   __
()( )( )( ) (  )
+------------------+
|                  |--+ < How does this point work?
+------------------+  |
                      |
                      |
                      |
                      |
                      |

I'm guessing that they are not directly spinning on the shaft, because then they would unscrew (or tighten) as they spin. So I think there must be a rod, which is tightened on the shaft, and a bearing around that, and then the pedal spins on this bearing. Is this correct?

If this is correct then the issue must have been with the bearings and removing and putting back the pedal wouldn't have helped. Am I correct?
The correct solution would have been probably to lubricate the bearings, but how can you do it? Can you take it apart and then assemble it again so precisely that it still works afterwards?

A pedal is made of two major components.

The pedal body, which is where your foot presses.  This part rotates around the pedal axle once per crank revolution.  It does not rotate with respect to the ground or your foot.
The pedal axle, which supports the body and threads into the crank arm.  The axle does not rotate with respect to the crank arm, but does rotate wrt to the ground and to your foot.
Sundries like bearings or bushings to reduce friction.

This is a modern pedal cutaway to show the axle (sometimes called a spindle or shaft.)  The pedal body should turn freely on the axle with minimal finger pressure.  A good shove of the body should make it spin around from 1 to 10 times.   Modern cheap plasticky pedals may only move a part of a turn.

Your hire bike probably had seized bearings in one pedal, making the body locked to the axle.  The quick fix is to add light lubricant in both sides if possible.  If that doesn't fix it, the hire shop should have quickly swapped out the pedal with a spare.   If they were plastic pedals then sometimes they crack in weird possibly hard to see places, but locking the bearings is a common consequence of damage.

Causes - bikes ridden in the wet/salt/grit/sand and put away dirty.  No bearing system likes dirt.   A good clean and relube can save a lot of pedals, but some are just too-far gone.


Giant ATX vs Escape? I'm planning to buy my first bike as an adult, mainly to go to work (about 6 km far from home). Today I went to the bike shop and tried a Giant Escape and and Giant ATX. From my unexperienced point of view the difference was that ATX have suspension, and it was noticiably more smooth to ride (I really like it). Although the Espace was very good, comparing to a mobike I'm used to ride.
The difference in price was not that much, 2000rmb (escape) to 2400rmb (atx). Although most of the home to work route is fine there are some parts where suspension might give extra welcome confort. But I also see its one more thing to add weight and maintenance to the bike.
Would you guys buy a montain bike to go to work? Or perhaps I should try another bike model?

Depends on the actual spec, but both bikes, as you've identified are fairly similar apart from the suspension.
https://www.giant-bicycles.com/us/atx-3
https://www.giant-bicycles.com/us/escape-3
The drivetrain & brakes are almost the same, but the Escape is slightly more road oriented with 700x38mm tyres, whereas the other has 26 or 27.5" x about 53mm (note: 26" is mostly obsolete for quality tyres, etc., so I'd prefer a 27.5" but on a cheap bike like this it probably doesn't matter much).
The highest gear is 48 x 14 on the Escape and 42x14 on the Atx, while low is 28/34 vs. 24/34. If you are on fast road then you might well like the 48x14 over the 42x14, but up a long steep climb or off road you could also use the lower gear.
The suspension on the ATX is one of the cheapest suspension forks around https://www.srsuntour.com/fileadmin/user_upload/Downloads/Consumer/Bike/Exploded%20views/2014/Suspension%20Fork/SF14-M%20Series/SF14-M3030-A-P-27.5-63%2C75-%281%29.PDF
It's just a spring damped by a piece of foam.
I'd consider it a downgrade on no suspension. Generally you can get enough suspension for most things with wide tyres at low pressure - the pneumatic tyres provide compliance with the road. I can ride over potholed roads with 23c tyres, but it's not fun. 38c is fine for potholed tarmac but if I was cycling over steep tracks that were never surfaced, I'd prefer a wider tyre than that. You can change these tyres yourself, but it's possible the fork/frame/brakes wouldn't fit wider tyres, so you'd need to check that. Keep in mind that in countries with good roads, 38c is already far wider than many people use.
Cheap suspension is popular with new cyclists, but experienced cyclists tend to prefer for cheap bikes like those you mention, no suspension, and then much more expensive and sophisticated suspension for actual mountain biking. This is because suspension adds weight, requires servicing, and may absorb your pedalling forces especially with such unsophisticated suspension which is not properly damped.


Single Chainring Conversion Just wondering if there is much point in having three chain rings on my MTB, I very rarely change gear on the front and I feel like having a single cog would make the bike lighter and also tidier as there would be less shifters and cabling getting in the way.

Is there any danger in fitting a single chainring?

Running 1x9 is a great idea. I have done it with relatively good success. There were always times on big rides i wish i had a granny.I also intially had issues on chain drop. Because the 9 speed rear, bumpy and rocky terrain can knock the chain off when the derailleur would slap.

To prevent chain drop on the front, you can run a bash guard, and an N-gear jump stop on the inside.


Why would the tension screw on a Brooks saddle have unscrewed to zero? What negative effects? Checking my saddle, the tension screw seems to have bottomed out to no tension applied.  I added a small amount of tension to the screw, and the screw seems to have "taken."  I've not tested if it will shake itself out, or unscrew by some other process.

1) Why would this happen?  A failure in periodic maintenance on my part to check that it was staying in alignment?

2) What negative effects would this have had on my saddle?

Checking the tension on a Brooks saddle is part of the regular maintainance. Any bolt that doesn't have sufficient tension on it will move due to random road vibration.

From

http://www.brooksengland.com/getting-in-touch/faqs/saddle_maintenance/

  Q: Why have the Rails / Tension Pin / Backplate on my Brooks saddle
  broken? By far the most common cause of breakages of the Rail,
  Backplate and Tension Pin is insufficient leather tension. Brooks
  recommend a routine six-monthly check of the tension, and adjustment
  where required.

A bolt stays in place due to the friction applied to the threads by the tension in the bolt. In effect you are "stretching" the bolt so it constantly pulls on the threads
to create the friction to hold the bolt in place. In the Brooks saddle case the force
is actually a compression, but the principal is the same.

As long as you put the tension back and check it on a regular basis, I don't think there should be any long term damage to the saddle.


Garmin Edge 1030 and Di2 Connection I just got a Garmin Edge 1030, and have newer Ultegra Di2 with the buttons on the hoods. I was excited to see that the Garmin can connect to Di2. When I look for it in the sensors, it is not coming up. Do I need to add an ANT+ transmitter to my current Di2 setup? I am not sure, or is that something that should already be installed and the problem is else where?

You need to install a D-Fly unit. Probably this one:  EW-WU111
Being able to use the Garmin in rain and cold weather with gloves is brilliant.
However check if you have the right components: these batteries are ok: BT-DN110 / BM-DN100


How to make a 10 year old electric bike battery work better? I have taken a 10 year old electric bike out of the garage a few weeks ago after not having used it for multiple years. The bike is an elops 7 bought at decathlon with a geonaute battery. It still looks very good and the mechanical parts seem to be working flawlessly (I still plan to take it to a checkout in the upcomings weeks). However I'm having some issues with the electrical parts:

When the motor is asking for too much power (when starting or when going up a hill), the control screen and the motor both go off. They can be turned on again but it takes some time and is not a viable solution. When the power needed is low, the motor functions perfectly.
The battery seems to lose its power quite quickly, sometimes it's at 3 bars out of 5, and it just goes completeley out of power.

I would like your opinion on the diagnostic and the solution to get it in better shape(and what I've tried so far).

It seems to me that there is a problem in the battery (which makes sense because it is old), when talking to a salesman, he said it was very probable for a battery this old.

To fix that I would like to change the battery, Decathlon told me the part is not made anymore and that they can't do anything for me. I couldn't find the model on geonaute's website either. The battery is 24V and 10Ah. Upon some research, a battery of this type seems to be around 100-150 euros but wouldn't have the right connectors. Some website also propose battery reconditioning but the price is around 300 euros and it seems very expensive.

Any idea is welcome and feel free to ask for more specific details.
Edit : Added pictures of the battery  and battery connector

As said, the batteries need replacing. They have a limited lifetime, regardless of use. You don't say if they are lead acid or lithium - if lead acid, they will certainly stuffed.
If Lithium they could last many more than 10 years, but only if stored correctly.  If replacement batteries cannot be purchased the best option is probably a rebuild. Virtually all battery packs are made up a collection of standard size cells, a rebuild involves stripping the battery and rebuilding with new cells.  Cell quality and price varies a lot, so shopping around for the cheapest is not always the way to go, but paying more does not mean you are paying for better quality cells.  When selecting a rebuilder, ensure they specify the cells they will be using - ideally a branded named once such as Panasonic or Sony, sourced from a reputable supplier. There are  a lot of counterfeit and low quality cells being sold these days.
Changing the connectors to use a different model battery pack is also an option, but you would need to know what you are doing. By the time you source a new battery and installed matching connectors you are likely close the cost of a rebuild.


Can any one tell me what make and model this bike is? Stolen today It's my bike which was stolen today, only image I have of it. Please, need for the police and insurance...

It's a Specialized Sirrus circa 2012-2014. Here's a video from 2013 that shows the bike in detail. Without part photos it's hard to tell the exact trim level, I suppose it's either a "Comp" or "Sport".
Notable features are:

Flat bars on a road bike.
Rim brakes.
Aluminium alloy frame.
Distinct paint scheme, especially on the fork.
Frame shape, tubes, junctions.

How I found it:
Google Image for "flat bar road bike rim brakes", look for bikes with matching features. "Sirrus" looked similar, so I searched for "Specialized Sirrus alloy rim brakes" next and look for one with same top tube and fork paint job, that's how I found the video. To narrow down the year and trim, I've looked for "Specialized Sirrus alloy 2011" and other years.
Good luck finding the bike, Patrick!


What is a good formula to translate a Google Maps cycle time estimate into a reasonable trip time for very long distances? I want to get to San Francisco from Los Angeles. I've looked at a number of options, including cycling. I have never biked such a great distance before, so I consulted Google.

It says that the trip will take one day and nineteen hours. If I suppose I travel eight hours a day, that's like five or six days. Is that the least bit accurate in the real world?

That is a reasonable estimate, however there is more to it than that. First of all, you are not going to be cycling the way you would drive, i.e. on the Interstate. For your particular plan you are most likely to be wanting to follow Highway 1 up the coast. This road is bicycle friendly whereas the Interstate is not. This comes at a price - more miles and more hills.

If you look at Highway 1 you will notice that it passes through some areas where nobody lives. The Big Sur coast down to San Simeon is rather remote, and, if you are looking for somewhere to stay over in that stretch then there are not a lot of options. Obviously San Luis Obispo and Monterey have motels, youth hostels and camp grounds to choose from so you need to do that stretch in a day.

Pushing on from Monterey into San Francisco is doable in a day if you are fit, however, you might kick yourself later for not going round the aquarium in Monterey or not having a snoot around Santa Cruz. Therefore you may want to stay over in Half Moon Bay where there is a Youth Hostel in a lighthouse. Staying there obviously means you have a manageable trip into San Francisco and you will not have to arrive there in the dead of night, as you would if you had cycled 'robot style' all the way from Monterey.

I would recommend that you budget seven days and base your individual daily rides on where to stay. You also need to bear in mind that lots of cyclists ride the entire Pacific coast route so, if you stay over in a cyclist-friendly place en-route, you may find yourself meeting up with others that are taking your exact same route. They may have started off in San Diego and have already found their cycling legs, they may also appreciate having you for company, particularly if you can set pace up hills or do turns at the front to give them a slipstream. You then might prefer riding with them and decide to do the route with them all the way, throwing your existing plans out of the window.

I advise that you buy the map of the route from the Adventure Cycling Association. This will provide you with the information you need to make the most out of your ride, that is if you are doing Highway 1. That includes bike paths, where there are good places to stay and where the nearest bike shops are.

http://www.adventurecycling.org/routes/pacificcoast.cfm


How do I identify an SR SunTour fork exact model? I recently located this SR SunTour service manual, containing schematics of a load of forks. Trouble is, my fork only has "XCR" on a sticker, and production date stamped.

At some forum this is discussed and links are provided to SunTour's XCM, XCR and XCR product lines. Strangely, my XCR does not match visually any of the presented (mine has no V-brake option).

Am I supposed to find a model number stamped somewhere on the fork, as with most other bicycle components, or should I deduce which fork it is from the features e.g. wheel size, brake options, outlook, locking and adjustment mechanisms.

I would be quite surprised if the model is not stamped. How do bicycle mechanics deduce the model - do they know them all from experience?

The fork should have a serial number. Not obvious and a little small and faint, something like tb0111xxxx. Mine was located on the lower assembly.

Go to https://www.srsuntour-cycling.com/service/ enter the number and it should come back with model type and year of manufacture. From that you should be able to find the exploded view pdf.


Randonneuring: Which UK 400k is appropriate for a new rider? I plan to attempt my first super randonneur series in the first half of next year. Picking a 200k and 300k are easy: I'll just ride my local ones (End of Hibernation 200 and Hauxton 300). And 600k is easy too: the Seething ride is easy to get to, and has a great reputation.

But which 400k should I attempt? The closest to me is the ride from Manningtree, but that's an unsupported event and it's not really all that close. If I'm going to travel, maybe it would better to enter one of the "classics" like the Irish Mail or the Llanfairpwllgwyn? I'm a pretty good climber, but not particularly fast.

So I'd appreciate some advice from experienced randonneurs.

If you're not familiar with the Audax UK calendar, then I'd still be interested in your advice in general terms: what characteristics of a 400 give the greatest chance of success (and enjoyment!) for a new rider? If I'm going to be too slow to sleep for more than an hour or two on route, does it matter that there are no sleep stops? How much of a difference do manned controls make, as opposed to self-service controls at ATMs and 24-hour garages? What about scenery and amount of climbing?

I've completed a handful of 400km brevets and organized one myself, but I can only speak to my experience in British Columbia (Canada) which is quite different riding than in the UK.  I find the 400km to be the hardest in the basic series and have heard other randonneurs (but not all) echo this feeling, so you're wise to choose this one carefully.

The biggest difference vs. the 300km is that most riders will spend a significant time of riding in the dark.  This depends on rider speed and time of year but it's not unusual to spend at least 100km in darkness.  Riding at night adds many additional challenges, including colder temperatures, sleep deprivation, difficulty navigating (signs are very easy to miss, landmarks disappear) and trouble finding fueling stops open at such a late hour.  That last point is important because calorie intake is critical on a 400km -- you can skimp on a 200km and even a 300km and still finish, but when you're cold and tired and sleep deprived after 20 hours on the bike, bonking comes very easily.

So as a new rider, I'd suggest looking for a few things:

A straightforward route that doesn't involve lots of turns or route-finding in the last 100km.
Don't pick an "epic" route for your first 400km or 600km brevet.  You will be surprised how tired your legs get after 300km when otherwise easy hills transform into steep ones.
Don't pick a boring route either.  Long-distance riding is very tough on the mind and it helps to have scenery to look at and the occasional hill to break up the rhythm.  But keep in mind that scenery doesn't really matter after dark -- all you'll see is the patch of road in front of you.
The ideal route uses low-traffic roads in good condition, and avoids crossing major cities/towns.
Plan out where you could stop in the second half of the ride for food: staffed controls (preferably with hot food like soup), pubs serving food late, all-night restaurants, and 24h gas stations & convenience stores.  You should also plan on bringing food with you in case these options don't work out.
I've never seen a sleep stop on a 400km (like the "Irish Mail").  On a 600km you normally don't build up enough of a time buffer to stop for a nap until around the 350km mark. At same point on a 400km, you're less than 3 hours from the finish anyway.  Unless you know you don't handle sleep deprivation well, a sleep stop is not a must.  You can always bring an emergency blanket and curl up under a tree or in a field if you're desperate for a nap.
Don't underestimate the importance of getting to the start.  You'll be more likely to ride something that's easy to get to, and will appreciate it even more when you have to make your way back home afterwards.

A few comments on the ride descriptions you posted:

Asparagus & Strawberries:  not much information posted, although the climbing (2600m) looks reasonable; being close to home is a plus.
Irish Mail: sounds like fun, hot food & sleep stop at 345km, easy navigation on return route, but lots of climbing (5600m).
LGL / Poynton 400km: mentions easy night navigation, 24h services; bonus points for the name.


Is a BB spindle sleeve required? So yesterday I washed my bike which is a Stock Components Surly Straggler 2015. I noted some squeaking around the BB even after lubing the chain so I decided to clean the bottom bracket. I didn't have the tools so I went out to buy them, and funnily, when I came back 2 hours later the squeak was gone. So it must have been related to water somehow. Anyhow, I now had the tools so I wanted to use them.. I removed the left crank and then the spindle. I noted then that the BB only has the two cups, but there's no sleeve, this center plastic tube through which the spindle runs:

I wonder why my bike is missing that piece? Is it not absolutely required?

EDIT: I found the Surly bottom bracket installation instructions here and from this PDF it seems like for my 68mm bracket, no sleeve is provided:

So I guess that the part isn't 'missing', and the mention of 'Road' use in the table could suggest that they assume you don't hit any dirt. The frame does have a small drain hole in the bracket. Well, but I DO hit the dirt. Can anyone suggest a BB upgrade? It somehow seems logical that a sleeve will protect better.

It's not required for the BB to function or the bearings to be located correctly or loaded correctly. It is only a shield against contamination, particularly from water that gets into the seattube at the seatpost opening. That said they're actually pretty important parts that do a lot to make the life of the BB what it should be.

I have no idea why yours might be missing. My guess would be a mistake when assembling or servicing the bike. Make sure it's not still in the BB shell. They pop on and off the cups easily so it could have gotten stuck in their. Sometimes you have to loosen the BB cable guide mounting screw for the BB sleeve to pass through.


Doubts about carbon fork condition I've recently bought a second-hand Fuji Jari 1.7 (http://archive.fujibikes.com/2018/Fuji/jari-172). It's in good condition and works without problems, the only thing I'm slightly worried about is the carbon fork.

The fork has weird looks to it. On some areas of the fork it looks like there's some sort of weaving showing, in some places there are lines that look like something left over from molding during production. Some parts, when looked at at a certain angle, are kind of cloudy or milky.

I've never had any carbon on any of my bikes before, so I'm not sure what to think of it. Hopefully this is normal look of raw carbon covered with transparent finish?

Please take a look at the pictures and comment. Otherwise than the strange looks, the fork seems perfectly OK -- the surface is uniform, there's no visible damage apart from some minor scratches on the finish, there are no weird sounds when I tap the fork all over, etc.

I think what you have is a lower end carbon fork where cost has been saved on the finish.

Carbon fiber composite is made from carbon fiber cloth in an epoxy matrix. The cloth weave often shows through the finish of CFC products. The finish in this fork seems to be somewhat variable. I think you are right that the lines on the inside are mold junction lines. Notice that are all on the inside surface to try to hide them.

What I would be more concerned about are the two vertical crack lines visible in the first photo, running parallel to the mould line above the cable exit. They may just be in the finish but I would have a bike repair shop check them out.


Do road bike shoes offer an increase in power transfer over mtb shoes if the sole is a similar stiffness? Is there an argument against the use of road shoes if your were planning on time trialling and criterium races?

It’s probably more a matter of pedal systems than shoes. High end shoes in both categories will be pretty good and stiff.

I can only talk about Speedplay Zero (road bike pedals) vs. Look Quartz and Shimano SPD. The Speedplay Zero have a much greater area, have completly free adjustable movement sideways (as far as the crankarms allow it) and no play, tilting etc. whatsoever. Other road bike systems will probably be similarly good.

Road bike shoes will probably be lighter and have more openings for air to come in.

The only disadvantage of road bike shoes is that it’s really almost impossible to walk in them and the cleats suffer much more wear from it.


What does welded and machined mean? I've got some Sun Rhynolyte rims and one of the features is being welded and machined. What does it mean when said in relation to a rim?

A rim is a piece of aluminum extrusion, rolled and joined into a hoop.

There are several types of joints used.

Rims can be pinned together using a piece of metal at the seam to hold the alignment.

Or the seam can be aligned and welded. This is the strongest method. Welded rims used to have a small bump at the seam from the welding process, which would wear smooth from brake use.

Someone came up with the idea to weld the seam for strength and then machine the braking surface smooth, which is the strongest and best kind of joint possible on a rim.


What's the story of Shimano PD-T780 Deore XT Pedals? I've seen these alleged XT group pedals on several web sites, but they aren't on Shimano's site. The "PD-T780 Deore XT Pedal" is sold at Arts Cyclery (http://www.artscyclery.com/), Amazon, and REI, but at none of my usual online bike retailers.

It's odd for an XT product -- it's a dual purpose flat/SPD pedal.

Was it an old product that's no longer sold? Could it be a counterfeit? (If so, weird that REI would sell it.)

From http://www.artscyclery.com/Shimano_PD-T780_XT_2-Way_Pedals/descpage-SHT78PD.html

Shimano often doesn't market or stock components targeted at the Euro trekking market in North America, including these pedals, many cranks belonging to their MTB groups with slightly upsized chainrings, generator hubs, etc. They're on Shimano's Cycling Europe site. Distributors and large retailers can generally get any of it specially brought in if they want.


Pedals wobble and click under load I've been maintaining my own bike for a while now, the one thing I haven't been able to fix is the pedals wobbling. This is a little hard to describe but hopefully it's understandable, and I've attached some pictures. The pedals wobble perpendicular to the crank arm, i.e. they move vertically. When I am riding, I hear a clicking noise especially when I'm pedalling hard, which I think is the pedal wobbling in the same way, but under more load. I've done a lot of googling and all I've found is either steps on removing the pedal (which I don't think is the issue as it seems tightly attached to the crank arm) or steps on fixing the crank arm itself, which I also don't think is the problem. Again having said all that, I'm very much new to this, so any corrections or advice would be massively appreciated. I did have a mechanic address this problem about a year ago, he mentioned it was difficult to adjust my pedals specifically but he was able to fix it, although I didn't ask him at the time exactly what he did. My concern is that if I don't fix this, it may cause damage elsewhere and lead to more expensive replacements.

The bike is a Trek FX 7.4, I haven't replaced any of the pedal or crank components but I also am not sure specifically what model the pedals are, although I can probably try to dig this up if it's helpful!

Examine the pedal and crank arm.

(Note that the above diagram is not exactly like your pedal, but the basic construction is the same.)
Note that there is a shaft that runs inside the pedal, from crank arm to the end of the pedal.  The pedal bearings (inside the central housing of the pedal) ride on the pedal shaft.  Likely the bearings have gotten loose and the pedal is rattling around on the shaft.  If this is the case you should go ahead and replace the pedals.
But carefully examine the shaft as you move the pedal up and down.  Where the shaft mates with the crank arm you will be able to see 10-15mm of the shaft, and you should not see ANY motion between this shaft and the crank arm.  If you see any motion there (while you move the pedal up and down) it means that the pedal is unscrewing from the crank arm and the crank arm will be very quickly damaged (if it isn't already).
Further, grasp the crank arm and move it in and out, checking for any flex between the arm and the crank shaft inside the bottom-bracket.  Any motion here must be corrected immediately (tighten the crank nut) or the crank arm and possibly crank shaft will be damaged.


Mystery little bolt fell off near rear axle Hi All! Please help with advice. I was doing some regular brush cleaning on my new Diamond Mission Pro bike that I purchased off the diamondback website (less then month old). A little bolt near rear axle that screws into the frame just fell off under my brush when I felt it was loose and touched it with my hand…

Should I try to replace anything under the warranty?

Thanks a lot in advance!

This bolt is used to hold the nut on Shimano E-Thru rear axles, it's usually a part of rear derailleur hanger or drive side dropout. I think it prevents the nut from rotating and the fact that it snapped off might be a symptom of loose rear wheel axle. Sections of recess around the bolt without paint might be where it touched the frame.

If you still have the frame/bike under warranty, I advise to contact the place you purchased it from. Even if the issue comes down to user error (loose axle), they will probably help to extract the remaining bolt section and source a replacement.

Alternatively, you can just make a slot for flat screwdriver and use the leftover as a grub screw (that's what my dropout uses, for example) or unthread it and use any suitable bolt instead.


Older road freewheels vs new mountain bike freewheels? I heard an interesting opinion yesterday that said all freewheels made back in the day (we were discussing this over a wheel with a Maillard hub and a Maeda (?) freewheel). The shop mechanic said that because it was made in the hey-day of freewheels, it was automatically better than anything made today, in which everything freewheel is being slowly phased out. Now I've tried out mountain/hybrid bike freewheels on a road bike, and I liked the ramps and such, but do the older freewheels (especially entry-mid level ones) really hold that much over modern freewheels?

This may sound a little opinion based, but I'm know there's a factual answer out there comparing weight, usability, durability, features, and other technical attributes which make a difference to general, everyday performance.

Also, I'm strictly comparing members of the thread-on class, not discussing the merits of cassettes and free-hubs and other modern technology. I tend to run a lot of older technology by virtue of it being cheaper to pick up and cheaper to replace when my daily is stolen and cheaper to maintain myself.

I don't think old freewheels are "better" by default. While it's true that most of today's thread-on freewheels are junk, that doesn't promote the junk of yesteryear to "desirable" status. However, perhaps the median quality level was higher back in the day.

In the days before freehubs, freewheels, like most things, ranged from the downright awful to the excellent. Regina made brilliant freewheels, as did TDC and several others, but they command stupid prices on Ebay these days. And even if you can find a nice NOS example, it will probably need a rebuild to run optimally.

Obviously there was a much bigger market for freewheels 30 years ago, with a higher profit margin, so manufacturers could afford to construct them well. These days it's less economically viable even to invest in quality tooling, let alone top-notch materials. In addition, today's manufacturing trends have shifted further towards light weight, at the expense of durability. Our disposable culture doesn't consider this a great loss, I suppose.

Perhaps it's fair to say that the old freewheels were built to last, but the vast majority of them, even in great condition, would be considered "a bit rough" by today's standards, especially when compared to modern freehub technology. Sadly there aren't any really high-end freewheels on the market today for a fair comparison...

1970s Regina = Ferrari

1950s TDC = Jaguar

1950s Atom = Peugeot

2010s IRO = Peugeot

2010s noname = junker


Alternatives for mineral brake fluid / oil (in a pinch) In case you don't have 'original' bicycle specific brake fluid on hand (e.g. "Magura Royal Blood"), what might be a good alternative to use (in a pinch)
 in hydraulic (disc) brakes? (for brakes that take mineral oil).

How long would such an alternative last? Which problems might occur and how soon?

I've read a few suggestions for alternatives:

Fork cartridge oil (the lighter (more viscous) variant)
Total / Castrol LHM Plus Fluid ( I believe it's power steering fluid)

Questions:

What are some alternative (/better) suggestions for alternatives?
Would the Total/Castrol LHM Fluid or fork cartridge oil be a good alternative?
Does anyone have experience with using either a fore mentioned options for brake fluid?
Would the heat generated by braking be an issue for either of these/other alternatives?

What are the requirements for a good braking oil/fluid?, my thoughts:

High boiling point
high fluidity

Do you agree with these requirements? Did I miss any or are some of them simply incorrect?

Any suggestions are welcome.
Thank you!

The rubber seals in mineral oil levers and calipers are very easily damaged by using the wrong fluid, and should this occur replacement seals aren't typically available. Experimenting with alternative or in-a-pinch brake fluids is a bad idea for this reason. The results are unpredictable. In the worst case, a brake failure could occur.

Running a different viscosity than intended can also alter brake performance. In particular, higher viscosity fluids have been known to sometimes cause either slower or incomplete piston return. Of course the specifics of the hose, brake, piston count, pad spring, etc are all going to play into that, a fact that no meathead MTB forum poster is ever going to consider for a hot second before telling you to go put LMH in your brakes just because they did it and it didn't blow up.

There's a type of DIYer who loves talking about how they've had their bike set up with hack X for Y years and it's totally fine, so it of course will always be fine for everyone forever. That's a good type of person to categorically ignore. Most of the time, their shadetree nonsense doesn't work as well as they want to believe, and they're really only out to appear as though they have something meaningful to contribute, when in fact the opposite is almost always true.


How do I determine the model of my Shimano Rear Derailleur? I recently damaged my rear derailleur and am trying to find the replacement online.  It is a Shimano Tourney SIS Index.  I have found several models in the Shimano website that are pretty close matches, but am wondering if there some way to determine the model or is there a hidden product number in the unit somewhere.

Practically there are only a few things that you need to match a rear derailleur to the one it's replacing.

The first is the mounting point - check the mounting to the frame is the same.

The other is the length of the cage - a short cage is typically used for road bikes and medium or long cage for mountain. The longer the cage, the bigger range of gears it can cope with, but the less precise the shifting is. As a rule try to stick to the same length cage, but if not, go longer rather than shorter (Unless you know what you are doing). try to stay with one for the number of gears as the chain, but it is not critical if its one either side. (i.e. an 8-speed on a 7-speed chain should be fine)

So if they're all pretty much compatible - you are probably wondering why such a large range - it's all down to weight, quality of shifting, expected life and price and just plain old marketing...

My advice - head down to the LBS (local bike shop) with your bike (or just the derailleur), and have a chat with them. They will have something off the shelf that will work, and you can discuss cost/quality etc. The LBS should be able to fit a new one in 1/2 hour if you want them to do it. I have had great success purchasing stuff or bikes online, however have also had the odd incompatibility due to not being aware of some seemingly minor detail.

If the end of the old cable is frayed/cut and not soldered, buy a new one.  it's just not worth the effort mucking around with the original cable, and they are only a few dollars.


Is cornering in snow any different? The general advice about cornering is to lean the bike, not the body, to put pressure on the outside foot, and not to brake or brake only with the rear brake if absolutely needed.

Well, does this advice hold for snowy terrain?

Today is my second day riding in snow this winter and still have the feeling that if I lean the bike, it will simply slide out under me. The tires are Schwalbe Land Cruiser. So I actually lean my body, keeping the bike as straight as possible through the turns. Exactly opposite to the general advice.

I am talking about 10km/h riding, and I already managed to fall a couple of times (luckily at those speeds falls are harmless, when outside traffic).

"On snow" for the purpose of this answer means autumn leaves, over which there are several cm of frozen, hard or melting snow.

I am fortunate that 1/3 of my commute is through a non-paved park, where I can practice funny things without the danger of being hit by a car. There are even some small (30cm) and other not so small ramps, but I haven't summoned the courage to jump those ... yet.

It's different insofar as walking on ice is different from walking on concrete. Traction is reduced anywhere from somewhat to greatly. It takes a much smaller change in direction, much smaller amount of braking, and much shallower lean angle in a turn to cause you to break traction. In terms of the physics and techniques involved, they're the same, though mountain bike techniques come in handy as you are likely to spend much more of your time without traction compared to typical riding on paved surfaces.


Is 650b a better platform than 26" or 29"? I have seen more and more reference to the 650b (27.5") mtb wheel size. Whilst I don't see any need for a new standard, does anyone know of any benefit to have a 27.5" wheel over a 26" or 29"?

While I understand there are currently 650b specific frames and wheels I haven't seen forks yet.

Also can someone please make a 650b tag, I don't have the rep yet. Thanks.

You might want to take a look a this question  which discusses the advantages of 29" over 26".

650b (or 27.5") falls somewhere in the middle and therefore performance characteristics will be somewhere in the middle of the two. For instance, 650b would be faster than 26" but slower than 29" at same chainring/cog. It would also roll over obstacles easier than a 26" but not as well as a 29".  Also, the weight would be somewhere in the middle.

It depends on what type of riding you are doing to determine which is the "better" platform.  Also, you should consider how easy it is to find parts in your area for a particular wheel.  Since 650b is only starting to gain popularity, it might be difficult for you to find the tires you want, or to find replacement tubes at your local bike store. Also, I'm pretty sure you have to have a completely different frame for all 3 options, as tires aren't really interchangeable at that large of a difference.  You could possibly put smaller tires on the frame than it is designed for, if you had disc brakes, but it might look odd, and might have weird handling.


My rear disk brake doesn't lock in place. Don't know whether hydraulic or mechanical My rear brake does not work (disc brake) MTB for anything.  It does not skid or even stop for that (brand new) What should I do?

I went to my local bike shop in India and he told me that disc brakes (rear) don't work well because the wire goes all the way to the back of the bike and gets twisted in the process.

I am 13 so I don't know much about disc brakes.  How can I make it lock easily?  How do I check whether mechanical/hydraulic?

You mention the brake is brand new.

Have you "bedded" the pads in?
Bedding involves riding down a hill and feathering the brake lightly.

The other possibility is pad / disc contamination. In particular oil.
Discs can be cleaned with appropriate solvent.
Pads can be cleaned by baking (faced down) on grease proof paper or gently heating over a flame to burn off the residue.