Can I pump my MTB tire to max (55 psi / 380 kPa) without the tube inside bursting? I have a e-mountain bike and I use to commute to uni every day. I have heard that higher tire pressures give you a bit more speed. My tires say I can pump to 55 psi (380 kPa) but I don't know if my tube can handle the same pressure. Don't want to buy a new tube. I currently have them at 40 psi (280 kPa). Will 47 to 50 psi (320–380 kPa) burst my tubes?

It can't burst the tube, because the tube is completely surrounded by the tyre and rim.

Bear in mind, though, that higher pressures don't automatically mean a faster ride. There are two competing factors: a soft tyre is constantly losing energy due to being squashed flat against the road, but a hard tyre loses energy because any bumps you go over have to lift the whole bike, instead of just deforming the tyre.  I don't ride mountain bikes so I don't know where that trade-off starts to bite.

On an e-bike, I'm not sure this will make much difference, though: it just means that the assist motor will have to work less hard at any given speed.


Bottom bracket is ticking Recently my 2008 Devinci mountain bike sounds like it's ticking when I push down on my left pedal on a usual rotation.

When I turn the bike over and go through rotations, I can't get it to tick.

When I put my left crank all the way down & jump a little on the left pedal, I don't get the ticking.  Only when I'm spinning.

The ticking isn't 100% consistent, but probably about 80-90% of the rotations have this tick.

I took it to my LBS, but they just said it was a bent chainring tooth - which it wasn't.

Does this sound like this is definitely the bottom bracket?

Thanks.

Update: I took it into my LBS to get the BB taken out & cleaned.  The tech said he couldn't find anything wrong with it, but did hear the ticking.  He greased & lubed anything that moved, and the sound lessened quite a bit.  I haven't had a good long ride on the bike since, so I haven't verified if the sound has gone away.

Final update: Went for a good ride & didn't hear the ticking, so it was likely the BB.

Bottom bracket noise is a frequent problem, and often hard to diagnose.

First and foremost, check the tightness of the crank bolts.  (Your LBS should have done this when they checked out the bike.)  A loose crank bolt can be the cause of BB noise, and failure to tend to the problem immediately (if not sooner) can result in irreparable damage to the crank arm.

After that there are a number of possible causes.  On a non-derailleur bike the chain may simply be too tight.  On a derailleur bike the chain may have a frozen link.  There may be a bent chainring tooth, or a deformed chain link.

Rarely, the problem can be due to bearing problems within the BB, but much more often with BB cartridges the cups have worked slightly loose and the cartridge is sliding back and forth in the housing (harmless and easily fixed).

On bikes with loose bearings (vs a cartridge) in the bottom bracket a loose cup can allow the crank to actually tilt slightly, such that the chain hangs up on the sprocket.  (This is easily diagnosed by simply grabbing the crank and shaking it -- there should be no bearing play detected.)

And pedal bearings seem (to me) to go out with aggravating frequency.

Then, of course, there's the "trick" knee or ankle that clicks sometimes.


Chainring: cheap vs expensive What am I getting out of a $55 chainring vs a $25 one? Are more-expensive ones longer-lasting, or more lightweight, ...?

This is for a $700 single-speed, to give you an idea of quality of bike I'm currently using (e.g. Not some $3000 professional racer)

You get what you pay for. Cost is going to be dependent on materials, engineering, etc. If you buy a cheap chain ring it may work pretty well if you don't demand a lot out of it. A more expensive chain ring will be made of better materials (will wear longer and be lighter) and be better engineered (usually an issue for shifting; not so much for a fixie).

When it comes to parts or tools I am usually dead set against buying "cheap" since you're not just paying for the materials and engineering but also the service and reputation. If you can get a decent part from a reputable place by all means go for it, but don't buy the cheapest part you can from some shady on-line guy and expect to be able to get any help when the mounting holes don't line up.


Going on a long distance bike tour: what kit do I need? I am going on a long distance bike tour and I am looking for advice as to the kind of equipment / bike set up I should use? I don't have a huge budget so what are the absolutely critical aspects I should invest my budget into?

(edit)
I have a mountain bike modified for touring, with XT running gear, Sunn Rhynolyte rims, Brooks saddle. But I want to get lighter wheels, more comfortable bars, and I'm considering a hub gear box.

I am planning on cycling across East China to Japan.

Would mostly be on the road, with some diversions down small side tracks.

Budget is about £3500.

For cycling across China you want a reliable bike that is unlikely to give you trouble, and which can be repaired with "local" resources if it does.

Forget about "lighter" wheels -- you want reliable wheels, and a pound less weight (if that) from a lighter wheel will not make any difference.  And I'd stay away from a geared hub, unless you can find one that you know is popular in China.

You do need a comfortable bar, but that's a personal thing and quite relative.

You should take at least two spare tubes, maybe a spare tire (see Sheldon Brown for how to fold it), patch kit(s), boots, and a good frame pump (don't rely on a "compact" model, and remember that you may have 20 flats, so going with CO2 alone is risky).  You should have some extra chain links and a chain tool (and make a crib sheet on how to use it), and maybe 2-4 "master links" of your favorite brand.  A few carefully chosen tools -- wrenches to fit seat bolt, crank arms, wheel axles (if not QR), etc.  And several spare spokes -- you generally need 3 sizes -- at least 2 of each.  Also, it's good to have the minimum tools needed to remove the cluster, in case you need to replace a spoke on that side.  (Assume that you can borrow, eg, a pipe wrench or some such to operate a cluster wrench.)  And don't forget the spoke wrench -- get a good quality one, not the one-size-fits-all ring thing.

Sun lotion, bug lotion, at least some "emergency" food, and a "road rash" first aid kit.  (Cortisone cream for bug bites is also often very handy, though toothpaste will work in a pinch.)

And whatever camping gear and clothing you need, based on how you will be traveling.  And, of course, maps, money (stashed several different places), lock for the bike (with extra cables to secure panniers), etc.

You might want to bring along some sort of trinkets to give to the locals as you meet them.  Simply some shiny new quarters would likely do, or you may have some other idea.


How to commute by (electric) bike in excessive heat I am from India and this is beginning of summer. I rented an electric bicycle for daily commute during winter but now it is difficult to do during summer screeching heat. What should I do to continue my cycling activity in summer while being eco friendly?

Updated: My office is 12km in one direction and it is not having much traffic. I generally leave to office at noon and it takes me 30-35 minutes to reach.

You mentioned that you rented an electric bicycle, I am assuming you still need to put in efforts and the motor just provides pedal assist.
Most pedelecs are limited to providing assist only up to 25 km/h.
Beyond this speed, the motor is cutoff and the rider has to put full effort to maintain the speed.
If this is true for your case, you will get the best outcome by maintaing speed just below 25 km/h.

Also watch your cadence, choose a gear that is not too hard or too easy so your body uses cardiovascular and leg muscles optimally.

You also mentioned you leave office at noon, so it looks like you are only concerned with the ride back home.
If sweating is your only concern, keep your self hydrated and go on anyway.
I would still advise you to follow your instincts and slow down or stop if you are feel exhausted.
Take a shower once you reach home and cool down for a few minutes.
Ensure you do not shock your body with too much of a temperature difference though.

The following are generic points which can help further.
Midday temperatures can reach 40°C in summer, where I live.
I plan my rides to avoid the hotter parts of the day.
My work hours are mostly fixed so commute to office is easy.
See if you can adjust your timings for this season if you are working in shifts.

I switched to riding in cycling shorts/jersey and change of clothes at office instead of riding in work dress.
Along with a good pair of sunglasses, a wet handkerchief under my helmet and another around the neck are useful accessories.
For longer rides, I found that squirting small amounts of water on my face from time to time feels good.

Another advice i started following is to ride slow for the last 5 mins etc. to allow my body to cool down.

When I have to go out in the afternoon or if there is any uncertainty in the duration i might have to spend outside, i take the public transport.
Car/bike pooling is another option that is still quite eco-friendly.

I keep myself hydrated with plain water, and with sugarcane juice or tender coconut water for longer rides.


Gary Fisher Kaitai suffers from handlebar wobble at moderate speed with 10lbs on rear rack I have a Gary Fisher Kaitai, their low-end hybrid.    I use the bike for commuting so I have a rear rack and typically carry between 5 and 12 lbs back there.  When I get up to moderate speed (10-15mph) and let go of the bars they begin to wobble badly.  This happens to a lesser degree when there is no load on the rear rack, as well. The wheels are true and balanced, and I am riding Bontrager 700X32 road tires.

Is it possible to correct this?

There are a few things that could help the shimmy, but there is no real silver bullet.

Typically the shimmy is a function of head tube angle, top tube length and frame (specifically top and down tube) elasticity. Jobst Brandt describes it best in this article so I won't get into too much detail on the whys. There are a few things that reduce or negate the shimmy that have worked to varying degrees for myself.

1) Knees against the top tube. Squeeze the top tube with your knees.
2) Stem length. Sometimes a longer stem might help out. Very frame dependent and you would not want to change your fit imo.
3) Handlebar bag. Distribute some weight to the front and see if a handlebar bag can help overcome the gyroscopic forces created by the wheel.
4) Switching to a set of tyres w/ more 'tread' (ie. knobbies). I haven't tried this but the jobst brandt article indicates this could work.

The Kaitai is pretty unique in its long top tube, exceedingly short head tube and relatively steep head angle. This also makes the bike a 'tough fit' for the majority of people.


How to adjust cleats to lower pain in the right foot's last two toes I'm getting started on road cycling, rode a few times with Shimano R540 SPD-SL pedals and compatible shoes, using the maximum float setting since I'm still getting comfortable with the system.

I've noticed right away that using cycling shoes has given me a great pain in the right foot. More specifically, on the fourth and fifth toes. I think they're getting jammed on the soles or maybe on the sides of the shoes.

I'm pretty sure I've got the right size shoes for me, since it's very comfortable and doesn't feel tight when wearing, so I guess it's a matter of adjusting the cleats.

I should mention that my right foot is the "dominant" one. It's the one I've gotten used to keep clipped in while standing, for instance.

Anybody got an idea for how I can try adjusting the cleats to lower the pain on the two outside toes? Put it more to the back of the shoes? More to the outside?

I suffer from pain in my feet on long rides. I believe it's caused by lack of blood flow and pressure on parts of my foot. I currently have a new pair of shoes and it is definitely worse when using those. You will probably find the issue improves as your shoes get properly broken in.


Converting a MTB to a Road Bike I just bought a new MTB and am planning to change my previous MTB into a Road Bike.

How do I do it? What kind of parts do I need to change or add or remove?

I am not looking to for a full conversion into specialised road bike. But like the answers are suggesting, I am looking for a bridge between commuter or road bike. My majors concerns to be met are:

Should be fast enough to compete with road racers over short distance
Should be light as a road
Should be as close as possible in as cheap as possible.

A mountain bike will never really be a road bike. The geometry and construction of the frame is different. Mountain bike frames are designed for a different posture and are often designed for a suspension fork, as well as generally being beefier.

You can set up a mountain bike with slick tires and drop bars if you want. I've tried this before and the ride quality is a bit off compared to a road bike.

If you want to take it all the way, you'll need to swap out the following:

you may need a rigid fork
you'd need to make sure that your frame and fork can accomodate 700c wheels and is drilled for caliper brakes. Many mountain bike frames will fail on at least one of these counts.
You'd also need to replace your crankset. Mountain bikes generally are geared much lower than road bikes.
your brake levers would need to be swapped to short-pull models meant to be mounted on a drop bar.
you'll need different shift levers probably.

All in all it's probably going to be a lot cheaper to get a used road bike and refurbish it than to convert an entire mountain bike.


SPD pedal float becomes restricted I have a strange problem with my clipless pedal float becoming restricted. I recently installed Shimano M520 SPD pedals on my bike, with SM-SH51 cleats on SixSixOne Expert MTB shoes. A few weeks after initial set-up, the right side started not floating correctly. The float range felt reduced, and even within that range the float felt like it had more friction/restriction and didn't glide like the other side. A very experienced (40+ years) bike fitter looked at it and was completely perplexed. We switched out the pedal -- no difference. Switched out the cleat and the problem seemed to be fixed. The only noticeable cleat wear was in the center of the trailing tab thing, on the surface facing down when pedaling (strangely, from what I can see, that part doesn't contact the pedal when clipped in).

It's now been 1 1/2 weeks since the cleat was installed, and the problem has returned (got gradually worse just the last few days), but there isn't the same wear pattern on the cleat. The float feels really tight, high friction, reduced range.

Things I've done to try to fix it: I cleaned around the cleat, made sure the cleat bolts were tight, checked for contact between shoe and pedal (normal; consistent with good side), and examined for any cleat wear (none perceptible). I tried clipping the right shoe into the left side by hand, but it's hard to tell any difference when not actually on the bike. Update: I tried using some silicone lube - helped for my morning commute (~10 mi), but evening commute was back to bad.

Has anyone experienced abnormal cleat float resistance/friction/reduction? Could the shoe be contributing to this? Any ideas what I could check or change?

(This is more a collection of thoughts to help youtowards an answer, than an actual answer)

If wear at that point causes the shoe to sit a touch lower in the pedal, and the rubber sole to press against the metal, you'll get extra friction.  My shoes are wth me, and show a similar wear spot; perhaps on your new cleats it's just not yet obvious.  And that spot might actually contact something.  I could believe so from about 4:46 into this video (M324s, but the mechanism should be very similar) and also from my own shoes (used with M424s)

Because I ride on M424s comnbined with walkable shoes, I had to file bits off the pedal to stop them binding against the shoes.  To find where they were binding I dampened the sole and dusted the pedal with coloured chalk, then clipped the pedal (off the bike) to the shoe held between my knees.  I could then see where the chalk stuck to the shoe. You might try something similar, though it might be easier to see where the chalk (alternatively talc) rubs off the shoe.  You may not be able to make the problem go away with the file as your pedals don't have much material, but a light trim of the sole in the right region might help.

Which foot do you unclip more?  The one that shows the trouble?

You can also try throwing some light grease over all the metal parts.


Chain hitting front derailleur cage with H limit screw fully loosened I followed the Park Tools guide to set up my gears. The rear derailleur was a success but I can't manage to adjust the front derailleur so that the chain stops grinding on the guard. There's no more give left in the H adjustment so I can't bring it forward. Any ideas?
As you can see by the paint damage, the chain has hit my frame many times in the 6 months I've owned the bike. The chain has never come off though.
One suspicion I have for the chain pushing against the derailleur cage is that the chainring is not fitted correctly, or has shifted. The photos show that it's on an angle. Is this cause for concern?
Thanks in advance.
For the images below, the chainring is set to the top and the casette is set to the bottom:

There's more to front derailleur adjustment than limit screws and cable tension.  Both the angle of the derailleur and the height need to be set properly.
The angle of the derailleur being off can cause chain rub against the cage.  If the rear of the cage is angled too far outward, the chain can rub against the inside of the cage when the chain is on the largest cogs.  If the derailleur is angled so the the rear of the cage is too close, the chain can rub against the outside of the cage in gear combinations where the chain is on the small cogs.
The derailleur looks to be canted slightly inwards towards the rear.
When looking down on it, I'd say it needs to be rotated counterclockwise to move the rear of the cage just a bit farther from the frame.
And that will likely affect the limit screw and cable tension settings.


How do you calculate aerobic and anaerobic heart rates? What are some of the methods to determine my aerobic/anaerobic heart rate threshold.

The classic DIY method is the Conconi test which requires you to be able to measure your power output and your heart rate, slowly increasing your power over time. E.g. starting at a very low level, you increase your output by a set amount every minute until you can no longer do it. At each stage you take your average heart rate. Then when you have the data, plot them on a graph, time along the bottom, heart rate on the y.

For this you'd need to be in a relatively sterile environment - it's not something you could easily or accurately do on the road. A turbo trainer is perfect, incrementing your output in watts or speed.

What you should see is that your curve will slowly grow with a reasonably consistent gradient, but there'll be a point where it takes over and climbs much more steeply. That's your anaerobic threshold.

It will be quite vague, but it'll be accurate to within a few beats - certainly enough to be able to set your next training outing a few beats below it for your threshold session.

For more specific results, you'll need to do some lactic acid testing ...


Cleaning and re-installing a crank As a result of needing to replace a chainring ( Worn out chainring or missing tension ), I'm about to reinstall a crank, and would like to clean it before doing so.
Regarding the next picture, can I:

clean outer (1) with soap for dishes (rinse), and before installing it, apply a very fine layer of all-purpose grease (conforms DIN 51802,  DIN 51825 part 2 and NLGI-class 2, made for long term greasing of motor and machine parts, specially for fast moving bearings)

clean inner (2) with rinse and scrub it with a plastic brush designed to clean drinking glasses, then apply very little grease to the thread

remove (3) the sealing ring, scrub the black, flat surface (update: I thougt this black surface was grease mixed with dirt, but no, it is clean black-painted metal) with rinse until it shines, then apply grease to it and put the seal ring on again.

apply (4) Loctite 243 to the screws of the smallest ring, since it originally was super hard to open and had this green stuff in it? Loctite 243 is red, apparently it can be used everywhere on the bike (I've never used it in my life and have a new one unopened). The outer and middle ring had no green stuff applied and were not hard to open.

Specially (3) is what worries me a bit, maybe it is better to leave it as-is

Next two pictures, what and how should I clean and grease something there? I've labeled parts for you to make easier references in the answer. The bike has a SM-BB52 bottom bracket.
Right:

Left:

I'm a bit embarrassed about the dirty frame.
What are things I absolutely should avoid doing?
I do have "chain cleaner spray", "break and parts cleaner spray" as well as isopropanol 99.9% at hand.

I think you may be over thinking this a little.
Firstly if you're going to take off the crank for cleaning you should probably remove the BB as well.
The Shimano manual covers what to grease and what not
https://si.shimano.com/api/publish/storage/pdf/en/dm/FC0002/DM-FC0002-13-ENG.pdf
Basically remove the BB, clean inside the shell with a paint brush. The BB isn't maintainable so you just wipe it off, and if there's play you throw it away and replace it with a new one.
Removing the BB and greasing the threads will help prevent water ingress, and you want to remove the BB about annually to stop things seizing up.
Generally I soak metal things (chainrings etc.) in petrol and it gets them clean. If you are eco-friendly you can probably find a greener less explosive degreaser. Anywhere you have rubber seals then petrol is likely to kill it, so avoid. Plus anything you can't re-grease you shouldn't degrease. So the bearings inside the BB are something you want to avoid getting any kind of cleaning agent into, so don't soak your BB in water or whatever, because that's only a good idea if the BB is user-serviceable which it is not (if it was user-serviceable you could fully degrease and then re-lube, but that's not the case). After cleaning metal parts in degreaser, rinse in water. No soap. Grease on parts that move or get tightened.
The chainring bolt torque is in the manual, 12-14Nm for the big/middle ring, 16-17Nm for the small one. The loctite will reflect that extra torque. Green loctite is the weaker one.
If you relate the 5mm bolts to the required torque, the function of the Loctite should be obvious

because 5mm bolts aren't typically good for more than about 12 Nm. Green loctite is wicking and it has a relatively low torque to break away (10 Nm), which is why it's not too hard to loosen, but has a higher prevail torque, which is the torque required to rotate it 180 degrees. Red loctite is much harder to break.


Changing my All City Mr. Pink to disc brakes Interested in changing to disc brakes on my bike. I hear they're a lot better, although I am rather new to this sport and this (Mr. Pink) is my first road bike. Any insight on the process of switching or any thoughts that I shouldn't switch the braking would be appreciated.

It’s not practical to do this. The frame needs to be built to take disc brakes, and this frame isn’t. In theory, you could find a custom framebuilder who could add the mounting points and reinforcements you’d need, but that would be very expensive. After that, you’d need new wheels and components.


On a bmx headset could an integrated bearing set be replaced with a caged bearing set? I have a 20" eastern with a 1 1/8" integrated headset. The problem being is that my headset's top sealed bearing is no good and I only have some caged bearings currently on hand. Is there any possible way to replace the integrated with the caged bearings without having to change out any external parts i.e. forks?

Pictures would help here, but I am 95% sure that you won't be able to do that because there is no race for the caged bearings to ride on.  Sealed bearings have the race built in and the frame/headset will have a shoulder that the bearings butts up against, but not a race.
The other issue you will run into is that most sealed bearings are press-fit and the fork tube and headset will be sized accordingly.  You can't press-fit a caged bearing...
Bottom line:  No.


Maintenance as my Derailleur are squeaking due to the everyday use and carelessness shown while changing gears while the cycle is static What extra steps should I take to extend the life of the Derailleur gears on my Btwin Rockrider 340 besides oiling them ?

My guess is that your chain is squeaking as it passes through the derailleur pulleys because it is dry.
Cleaning, lubrication and correct adjustment are the keys to long life with a bicycle.

If the chain is dry and not dirty all you need is some bicycle chain appropriate lubricant (lots of choices)
If the chain is dirty and dry you can clean the chain on the bike (a quick Google of "bicycle chain lubrication" will give you lots of information)
If you lubricate the chain and it is the derailleur squeaking use a bike appropriate lubricant on the pulleys and the pivot points on the derailleur.

Changing gears while the bike is not moving may cause the cables to stretch and effect shifting quality, but it's unlikely to cause the derailleur to squeak.


Cyclocross Bike On the Road I ride road and MTB, but want to add a cyclocross bike and do long distance, all day adventures which would include 50/50 (road/off-road).  I am not interested in racing, but do want to participate in events, etc.  My question: What are the best tires to run on a CX bike under these circumstances?  Thanks.

I've ridden many different tires on my cyclocross bike, and I've found that a 32 mm is the comfortable on the road.

The most fun I've had though is on 40mm Clements, especially if there's any off road involved, if you can fit them on your cross bike.

https://www.biketiresdirect.com/product/clement-xplor-mso-60-tpi-adventure-tire


GT Chuck 1.0 component transfer to full full suspension frame I own a GT chucker 1.0 but want to upgrade to a full suspension. Would it be posible to transfer all the components (fork, wheels, disc brakes, crankset, drive train) to a full suspension frame (xc/all mountain full suspension frame)?

Assuming that all of the receiving sizes are the same, then yes. Technically you can put parts sized for different wheel sizes on a frame meant for a specific wheel size (ala 69ers), but keep in mind that it will change the bike's handling and geometry.

Fork: If both are 1 1/8" or both tapered then you can. Keep in mind that the head tube of the new frame may be shorter or longer and affect how much steer tube sticks out. You could wind up without enough space to clamp the stem. Also, will you need to transfer headset cups and/or bearings?
Wheels: The front wheel can go if the fork fits, if not it just needs to fit the new fork. The rear wheel will need to have the same spacing and dropouts (135mm QR, thru-axle, 12x142mm, etc.).
Brakes: You might need an adapter to mount the brakes, but these are pretty universal and should work on any bike. Also check to make sure the hoses are long enough if the new frame is longer.
Drivetrain:

Cranks: Will work, but the bottom bracket must be of the same type (cups/pressfit) and size (68/73 or 83mm).
Shifters: are similar to brakes in that they're universal but the cables might be too short.
Front derailleur: Must be the same mounting type. The swing might be different, but it will work in some fashion, but maybe not the best.
Rear derailleur/cassette: The cassette is dependent on the wheel fitting obviously, but the rear mech should work fine.
Chain: I would say probably not, you'll have a slightly different chain size and it's a new bike, so might as well put on a new one. Plus, don't forget about the chain length change as the suspension moves through it's travel.

My recommendation is to compare the specs on both bikes and see how much is the same before deciding to swap all the components, as it will be a headache when you get halfway through the build and discover that you need to buy a different sized part! This is also a good time to upgrade components and evaluate wear.


Is the Power Pilot the only speedometer / computer that will work on a LeMond Revolution Trainer? After just purchasing a Lemond Revolution trainer, I noticed and realized as soon as I set it up that I would be loosing my rear wheel and its spoke attached speedometer magnet.

Are there any alternatives to buying the Lemond Power Pilot for Revolution? The Power Pilot at $439 USD its quite an expensive piece of hardware, costing nearly as much as the trainer did itself.

No it looks the Power Pilot is not your only option. It may be the case that any standard magnetic bicycle speedometer can be made to work with the Lemond Revolution trainer. The Lemond revolution does have an embebed magnetic sensor in it's flywheel. So all that is needed is a way to position and attach a speedometer sensor, so that it can read the magnet embedded in the flywheel.

My Experiment which resulted in a working and realistic reading from my low cost speedometer setup consisting of the following ingredients:

Bell Platinum Series, Bell Wireless Cyclocomputer
Four zip ties
Sturdy heavy gauge steel wire
Electrical tape (to wrap around the wire to protect the bicycles paint)
Pliers to bend and shape the wire such that the sensor lines up properly with the magnet.


Should I remove the chain before installing new rear derailleur? I want to put a new Sram X7 instead of killed one, should I open the chain (if I have no chain lock) or it's better to open the derailleur?

It's much better to open the chain. Derailleurs are not really designed to be opened repeatedly, and doing so inexpertly can potentially ruin the derailleur. Chains might have either a lock link or a master link of some kind, find that open the chain and then thread the chain through the derailleur. If the chain does not have one of these links, you will need a chain tool to split the chain. DIY grade ones are quite cheap and do the job well, but you will need to read up on how to use it properly.

Also consider that if the size of the derailleur arm is different, your chain may need either fewer links or more links to fit properly.


Tips for first time cyclist on 9W in NJ/NY Not sure I can find a group in my area that fits for me. Up until now I've been mainly sticking to local rides in areas without a lot of car traffic. Lately I've been riding more with destinations in mind. I've never taken a bike ride from the George Washington Bridge up 9W towards NY but I would like to.

I mapped out the ride on google maps and it shows that sometimes you ride against traffic and sometimes you ride on the side with traffic. Could someone explain why and where you switch or have a cue sheet? Couldn't find a cue sheet online and the navigation on my android phone doesn't seem to support cycling which has caused me some problems when I've tried to use it on rides.

An additional resource is Stava. You can join for free, and there is an Android app on the Google Play Store.

To start planning your ride see this Stava map; zoom for more detail. Maybe you'll need to have signed up to see it.

If you set up (or find a route) for your ride, you can download or print cue sheets like this one.

There are several Bicycles.SE members with local knowledge; hopefully they'll post more explicit answers :-)


What are the different types of bottom brackets? Right now I am only familiar with two types of BBs (bottom brackets):

The square type on my older mountain bike.
The hallowtech (SM-BB70) that comes with a Deore XT crank I bought on my newer bike. I'm assuming hallowtech is a newer technology. Its waaay lighter than the square type one because of the hallow tubing.

But then I read about pressfit BBs. After a bit of reading I could not find a good comparison between the SM-BB70 and pressfit BB.

Are there other BBs I dont know of? Also if someone could provide a list of pros and cons for the different type of BBs that would be a big plus! Thanks in advance.

I think that in answering this question, it's important to understand that the differences in bottom brackets themselves is partly due to the cranks that match said bottom bracket 'doing more of the work', so the crank and BB need to be seen as a system for the whole picture.

One-piece cranks ("Ashtabula")

In this system, the crankarms are a single piece of metal bent into a "Z" shape, with threading on parts of the spindle section of the crank (the part that goes through the frame). Bearing cups are pressed into the frame, then the crankarms are inserted through in one piece. bearings go between the frame cups and cones that thread onto the crank spindle. The Park Tool One-Piece Bottom Bracket service page has lots of nice pictures that might help figure out how things go together.

Three-piece cranks

These cranksets consist of a left and a right crankarm, which both attach onto a spindle which is part of the bottom bracket. Usually these BBs will thread into the frame, with the majority of the assembly being one piece that threads into the drive- (right-hand) side of the frame, and then a (usually plastic in the case of Shimano bottom brackets) supporting piece will thread into the non-drive-side to take some of the load off the drive-side threads.

Examples of spindle systems for three-piece cranks are square-taper (both ISO and JIS standards), Shimano Octalink splined and ISIS splined. These BB standards all thread into the frame. The crankarms usually attach to the spindle via a bolt that threads into the end of the spindle.

Two-piece cranks

In recent years, most higher-end cranksets have switched to a construction where the spindle and drive-side crank/spider assembly are integrated into a single unit. This means that the bottom bracket no longer needs to have a spindle, and is now essentially a pair of bearings that support the crank spindle. The variation in where these bearings are placed, their size, and how they are mounted in the frame causes the wide range of modern bottom brackets.

Narrow-diameter spindles (≈ 24 mm)

Shimano's Hollowtech II and FSA's MegaExo both use a spindle diameter of 24 mm, and are most commonly used with external bearing BB's that thread into the frame, such as the SM-BB70 you mention.

SRAM's GXP system uses a 24 mm spindle on the drive size which narrows to 22 mm on the non-drive side, which they say avoids having to adjust the axial loading ('preload') on the bearings during installation.

Large diameter spindles (30 mm)

In the search for lighter and stiffer cranks, the diameter of the spindle was increased to 30 mm from the previous 24 mm. However, the cartridge bearings for a 30 mm spindle have an outer diameter that is too large to be attached with threaded external bearing cups, so most new systems moved to 'press-fit' BBs. There are a number of standards, the first of which was Cannondale's BB30, where the cartridge bearings are pressed directly into a machined bottom bracket shell in the frame.

However, because the manufacturing tolerances required to achieve a good fit for the bearings in a BB30 system are very tight (and therefore expensive to manufacture), other manufacturers switched to PF30, which uses the same cranksets as BB30 but rather than pressing the bearings directly into the frame, plastic bearing cups are pressed in first, and then the bearings are pressed into the cups.

Mixtures

Very recently, FSA have introduced their BB386EVO cranks, which have the same diameter spindle as BB30/PF30 cranks, but the spindle is wider. The wider spindle means that FSA can offer a BSA threaded frame to 30 mm crank bottom bracket, but that the crank can still fit to BB30/PF30 just by adding spacers to the spindle to make up for the narrower BB width of those standards.

There are also standards, which I do not know as much about, which concern press-fit bearings sized to accept 24 mm cranks, including "Shimano press-fit" (colloquially BB86 or BB92), and Trek's BB90, which uses slip-fit bearings like an integrated headset, as opposed to bearings that must be pressed in with force.

Campagnolo

Campagnolo produce three types of cranksets at the moment. Power Torque is their name for a two-piece crank similar to Shimano Hollowtech, however the bearings are not part of the bottom bracket, instead they are pre-installed on the crank spindle before it is inserted into the frame.

They also produce Over-Torque, which is a 30 mm spindle design compatible with BSA threaded frames and most press-fit systems, and Ultra Torque which splits the spindle in two at its midpoint.

(Apologies for the lack of detail in the Campy section.)


How do you bicycle the most efficiently on a road bicycle? I assume this has been studied to no end for e.g. UCI governed bicycle racing, and probably by others as well.

Simply:

How do you ride the most efficiently, in the context of putting down power?

I'm ignoring aerodynamics and bicycle attributes here entirely. Assume a generic road bicycle on any road course. Before anyone screams that it depends on the road you're bicycling, let me just state that I'm looking for a generic answer that can be applied to any stretch of road. A set of simple guidelines, or "rule of thumb" for how to bicycle the most efficiently.

How do you distribute your power budget? Should the rider put down extra power when going uphill? On the level surface? When going downhill? I think I've seen riders often rest when going downhill, is this due to such a rule of thumb -- that this is considered to be optimal, or is it due to personal preference?

Surely there must be a sweet spot in the graph for any inclination -- where efficiency is given as a function of a few parameters, the inclination, the power put down, and the wind resistance? Something like that?

If this is indeed subjective, and cannot be answered on a general basis, then I accept that as an answer. The simple fact that there is no guidelines to be given and nothing to be said on the matter would at least give me some peace of mind.

Whenever I bicycle, I'm always questioning myself, if I'm doing it wrong in terms of how I put down power. If someone could point me to a study that explains how and when to put down power that would be great, or a study that explains why such a thing is impossible.

The first answer is: you bike most efficiently inside a peloton (where air resistance is lowest)
The second answer (in a GCN video of a sprinter): you do a lot or close to no effort in order to stay at a certain speed (stay on the average). Any increase of speed means you lose a lot more to aerodynamic effect. This usually means you give everything on uphills and recover on downhills (assuming sprint-type uphills and downhills, i.e. 5% or so).

The general idea is that the average speed is much more affected by slow segments than by fast segments, so you want to increase as much as possible the speed on the slow segments, even with a significant decrease on the fast segments (if you drive 99km at 99 km/h and 1km at 1 km/h, the average speed over those 100km is about 50 km/h - one percent of the length at a very low speed just about halves the average on the rest)


How can I bleed my hydraulic disc brakes without buying a kit? Is it possible to bleed hydraulic disc brakes without buying a kit?  If so, how would I go about doing it?

I have Shimano BR-M355 brakes, but the question is also applicable to other manufacturers.

What would I need to be able to bleed these brakes, and how does the end result compare?  In the UK a Shimano kit is approx. £30 [Sept 2016] including brake fluid.

It depends on your brakes.

Some models need nothing more than a couple of short lengths of plastic hose, a cloths peg and syringe. Others need fittings to attach the hose(s) to the brakes, and you may or may not find something else to do the job in a hardware shop.

Kits are mostly relatively cheap and probably cost no more than individual bits purchased  from a shop. Some kits are expensive (Avid comes to mind) - probably because you have no choice and have to buy it for the proprietary bits needed to do the job.


Chain for Huffy beach cruiser The chain broke on my Huffy 26" Cranbrook Beach Cruiser. What chain do I buy? Size and speed? I think it's multi speed!

At the bike rental store I had we rented single speed cruisers. Single speed and mulit-speed, done with multi-speed hub (sometimes called internal gearing, hub has a single drive gear) is usually 1/8" width size 1/2" spacing, generic stuff. Lots of choices for plating and color if you want a little fancy or rust resistance. Now when you say multi-speed with rear derailleur, there's the kicker. You'll need a little skinnier to get through the drive-train. Get a generic 3/32" multi-speed chain my best guess for Huffy match. You see any word on the derailleur (for example) like Shimano or other brand?? Buy specific to gear train brand for best performance and also to number of gears too. For example you could be rocking a 5-speed cruiser with a low end Shimano derailleur, probably with a big cage between gear pulleys. In this example case, I recommend (not brand, just example) but I'd match brand, so buy Shimano/ 5spd/ multi-speed chain. Use the old chain to match number of links, but don't trust it for sizing. Chain stretch is a real thing, sometimes 1-2 full links. I've seen great YT videos for chain sizing on both types of drivetrain. FYI, fit on a single speed is adjusted with dropout and length so the chain is no looser than about a 1" bounce to it.


Can we turn a fixie bike into a freewheeler? I'm new to the fixie world. I'm planning to buy a fixie bike though, but to start right away would be difficult especially when I'm pedaling down hill. Is it possible to change the fixie bike into the freewheeler with both front and back brakes?

Please HELP!

You can buy a flip hub rear wheel where one side is fixed, the other free (Some bikes even come with them). You just take the wheel off, flip sides and put it back on. Brakes will depend on the frame but most frames allow for the installation of brakes. For the rear brake, you'll just have run full cable housing along the frame with either wire ties or cable clamps.


What is going on with my derailleur? I was on a ride a few months ago and while shifting, my chain came out of my derailleur. So this is a little confusing. Let me explain. The chain was resting on the outside of the bottom part of the rear derailleur cage. There is a little silver cylinder behind the lower jockey wheel that touches but doesn't actually connect the two sides of the cage. Somehow my chain go pushed to the outside of that. When it happened it felt like the chain had gotten shifted off and my cranks jammed up. I stopped pedaling as quick as I could.
Anyways, to get home I had to take out the bolt that secures the bottom jockey wheel in the cage, and open the cage up to get the chain back on the correct side of the silver cylinder. I put the jockey wheel back in with the chain in place and limped home.
I took the bike to the LBS and explained the problem. They didn't know what might have caused it. They checked the hanger, and it was a little out of alignment, but they said it wasn't that bad and fixed it. I also asked them to check that the derailleur itself wasn't bent, but who knows if they actually did that.
Flash forward to yesterday and the same thing happened. I fixed it the same way and limped home again. I've never seen this before and definitely don't want it to happen when I am sprinting.
A few things:

My derailleur is an 11 speed Dura-Ace.
Chain is not worn/bent/no frozen links
Cassette is near new
I was shifting both times, but not putting a lot of power down.
Hanger should have been OK.
The bike has less than 1,000 miles on it
I didn't notice any wear on the bolt or threads and the bolt was tight as could be with locktite in the threads both times

Any idea what might be going on/how to fix it?

I see no way for the pictured setup to occur while riding.

The silver bushing is bolted or rivetted to the cage plates
Cage plates are contiguous plates of steel with no gaps
Lower jockey wheel is also bolted to chain plates.

These three items form a box through which the chain runs.  No amount of folding or flipping the chain would get it out of that box.

The only options I can think of are

Someone misassembled the chain in the first place - Plausible because the chain is low tension at that point, and you may not notice the clattering.  I've personally ridden with a group ride up a gravel track and someone else only noticed the same problem halfway up (hi Brendon!)
Notice the scarring on that bushing - the chain has been running on it for a while.
Someone has fiddled with your chain while the bike is out of your sight. Unlikely because its a dirty business messing with chains and that's a long way to go for a joke

If your chain has a quicklink then fixing is easy and can be done roadsize with pliers, or some people can split them by hand.

Opinion  If the bushing is only attached on one side. then its not doing you a lot of good.  Consider removing it completely and see how things go.  Store the small part, in case it gets worse and you need to refit it later.


Inner tube valve fit/pumping question I have an old double trailer from when my kids were little that I kept and use to haul stuff. Yesterday I heard a loud bang while it was sitting in the driveway, and it turns out one of the inner tubes blew. It is not repairable.
I have been searching for hours for this type of tube, without success:
16x1.75 with a bent Schrader valve
It has to be bent because the wheel is solid. The original one was a Kenda, I can find them with straight valves, or I can find wider ones (2.125 and up), but not this size with a bent valve (except for Ebay with shipping from China, but I don't want to wait until August). Should I get one with a straight valve and try to bend it/squeeze it in, or get a 2.25 inch wide tube for my 1.75 tire?

This trailer does not travel far or fast, but it has to carry heavy loads.

To buy time, I'd attempt a patch.  Since the damage looks bigger than a commercial patch, I'd cut a larger piece from an old inner tube, and make one.  Downside, any other part of this  old tube could fail in the same way.  Changing tube with a load-on is challenging.
When you do find a supplier, buy at least three tubes, two for trailer, one for spare and any more to store at home.
My searching shows they are available, but 1.75 is rare and 2.125 is more common.  You could stuff this larger tube in your existing tyres, and they would be a little more robust due to less stretch, but harder to mount without pinching.   So consider your existing tyres and whether its time to replace them with 16" x 2.125", or more.  3" seems to be a common size too.
Which leads to - Have you ever weighed your loaded trailer?  Get a bathroom scale and in turn put it under each wheel and the drawbar.  Sum the three weights, and that's your total.  Guessing you carry 50-80 kg in there, so a wider/stronger tyre will help.   The recommended max for my trailer is 55 pounds/25 kilograms, but I've carried 100 kg of UPSs successfully.  More-robust tyres certainly help !


Avoid problems with ratchet straps to fasten MTB shoes With shoes like those shown below, when you adjust the buckle to the most tight position, the release handle is blocked (IMHO, this is due to bad engineering but cannot be changed.) Usually, this happens to me during several hour bike rides after readjusting, i.e. tightening the ratchet strap. As a result, I have to use tricks like inserting thin sheets of metal between the buckle and the strap, which is especially tricky in places where you do not have those devices around.

The major question is, how can I avoid this with my existing shoes? E.g. I was thinking of "inserting something" so that the most tight position is blocked.

However, I am also wondering whether I am the only one who experiences this problem, i.e. whether I am the problem, by e.g. buying shoes that are too large (by common standards, this is not the case) or by feet that shrink much more than average during pedaling.

EDIT: Regarding myself as a problem, I should add that due to a rare type of blood cancer, my blood is "thicker" (which is a physically incorrect term) than average, resulting in a bad (micro)circulation, especially during long exercise. Hence, an optimum solution would not increase the chance for unwanted heating, e.g. by wearing additional socks.

To fix your existing shoes, I would either move where the strap attaches to the "tongue" of the shoe or where the buckle is fixed to the side of the shoe. The straps are designed to be replaceable ( as well as the buckles ).

I would take a closer look at your shoes, many Shimano models have small screws that fasten the buckle to the shoe so it can be replaced. If I am remembering correctly, they also have two sets of positions so you can place the buckle lower
on the shoe if you want.

Even if this is not the case with your shoes, you should be able to move the position of the buckle using pop rivets. This is something skiers do with ski boots all the time, so if your local cobbler can't handle the problem, you might try a ski shop.


How do I wash a bike indoors? There are many sources describing how to wash your bike but all of them are for people who live outside town with a nice garden and a lot of space. Provably most of people live in small flats in a city block making it impossible to use these guides.

How can I wash a bike properly without going outside and having really small space?

I never wash any of my bikes with water. Water, specially at high pressure out of a hose may get to places it shouldn't (i.e. bearings) and thus reduces the life expectancy of your bike.

Personally, I don't have a lot of space inside, and this works perfectly fine:

let your bike dry completely
scrub off all bigger chunks of dirty with an old dry cloth
use a cleaning agent (ideally something like WD40) for stains that don't come off easily
degrease your chain, also using a bit of WD40 and some dry cloth
possibly remove wheels from frame if you really wanna get everything off
reassemble everything, grease movable parts using a little bit (!) of chain oil or thicker grease (i.e. motorex) if needed
most importantly: repeat regularely, so your bike never becomes too flithy


Chain slipping off derailleur jockey Last week, I had to abandon a training ride due to my chain slipping off my rear derailleur jockey wheel. This would only happen when shifting, and most often when either shifting chainrings or shifting multiple cogs in one go. I took the bike in to my LBS, and they diagnosed it as a bent derailleur hanger — a reasonable guess, given I took a spill in a crit the previous week (although, curiously, I did not have any problems in the race between my wreck and the training ride). They bent the hanger back into place and sent me on my way.

Tonight, on my first ride after the fix, the problem was happening again. Same deal, but less frequent. Shifting multiple cogs, especially right before/after a chainring shift would reproduce the problem with a high probability. After getting home, I put my bike in my stand and checked the alignment with a derailleur alignment gauge. It's absolutely perfect. And yet a little shifting while in the stand and I was able to easily reproduce the problem.

To recap:

chain slips off bottom derailleur jockey wheel
perfect derailleur hanger alignment
only during "significant" shifts
not limited to shifting under load
SRAM Force components

Pics are below. Any ideas? If more pictures are necessary in order to diagnose the problem, I'll be happy to provide.

Edit: After discussion in the comments, the problem is almost certainly that the derailleur cage is twisted and misaligned. Time for a new derailleur.

Edit 2: New derailleur purchased. Problem solved.

This type of problem has 5 likely causes, listed in order of elimination.

Bent dérailleur hanger, or Bent derailleur cage. (Your derailleur hanger looks straight, but the cage appears slightly twisted in the upper photo. Could be the angle of the shot, though.) Edit: This turned out to be the correct answer, after all.
Bent, twisted, or sticky chain link.
Badly worn dérailleur pulley wheels. This means there is not enough tooth left to hold the chain on the pulley wheel. (In my opinion this is most likely, but I'd need a photo of the derailleur side on to confirm.)
Worn chain. A badly worn chain will slip off the pulleys in this manner, sometimes. Usually, you would also experience slow and noisy shifting in the rear gears.
Worn cassette. Usually, you would also experience slow and noisy shifting in the rear gears, not just the pulley derailment, and usually it would be preceded by a worn chain. But it is possible, especially if the chain has recently been changed.

You've checked the derailleur hanger, so #1 is less likely. Although I would look at the derailleur cage or body. It really does appear bent in the second photo, unless the derailment is putting outside pressure on it.

You would see and feel #2 on the repair stand, so I assume that is unlikely, although it's easy to check and eliminate.

'#3 is my guess, without a side photo to confirm it. This is a photo of the difference between worn and unworn pulleys. Keep in mind, this is an extreme difference, and yours don't need to look this bad to cause your problem. Edit: After new photos, there is some wear, but not enough to cause the issue.

A worn chain is easy to check. Use the Park tool gauge or a similar tool to measure the wear. On that gauge, to see this issue, I would expect close to 1mm of wear.

A worn cassette is usually preceded by a worn chain, so if your chain is badly worn, you may need to change the cassette as well. Worst case, you may need new chain rings as well, but that is less likely.

Edited to include troubleshooting steps and conclusion:

After talking through the issue with Stephen, and looking at new and more direct photos, it is clear that the derailleur cage or body is misaligned, as discussed in option #1.

There is pulley wear as discussed in option #3, but not to a major degree.

You can follow the logic in the comments below:

Derailleur hanger is confirmed straight by my own DAG. Cage might be twisted. I'll check, and upload a pic with a dead-on shot. It's carbon fiber, though — will CF bend? No sticky chain links. I'll put a new chain on to rule out #2 and #4, though. How would a worn cassette cause the issue, given that this is happening before the chain enters the cassette? – Stephen Touset 42 mins ago
A worn cassette can cause the chain to be out of line with the derailleur slightly. It's less likely, but possible. That's why it's at the end of the list. – zenbike♦ 34 mins ago
A CF derailleur cage isn't likely bent, but the derailleur body might be. In the photo, it looks twisted to the outside, so check whether the pulleys run parallel to the cogs when there is no chain on it. Only your outer plate in carbon.If the inner plate is bent or twisted, the CF plate has enough give to move with it. – zenbike♦ 32 mins ago
More pics uploaded. In the rear pic, the chain on the bottom derailleur looks a bit to the right, but this seems to be that the chain is just pushed all the way to one side of the teeth. There is about +/- 3˚–5˚ of play in the jockeys. Normal? – Stephen Touset 21 mins ago
Actually, the play is normal, especially in th upper pulley. But that derailleur cage is not aligned correctly. The cog of the gear it's in, and both pulleys should make a straight line, as perfectly vertical as possible. In that photo, ignoring the chain, the upper pulley is twisted slightly toward the frame, and the lower is even farther out of line. It is still possible that it is the angle of the photo, but it doesn't appear to be. You're also showing wear on the derailleur pulleys, if not nearly as bad as in the photo I posted. I'd say it's time for a new rear dérailleur. The cage itself should be parallel to the cogs, and that isn't the case either. – zenbike♦ 13 mins ago
One question: Have you recently disassembled the derailleur? Is there more float side to side in the lower pulley than in the upper? – zenbike♦ 8 mins ago
No to disassembly. Much more float in the upper pulley than the lower. Looks like you're right with the alignment. New derailleur time. Anything I can do in the meantime to minimize the chance of problems this weekend? As in, what should I try and bend to correct the misalignment as best I can? – Stephen Touset 8 mins ago
Ok. Well, you can try to bend the cage back in to alignment. If you take the photo you posted last, and lay a ruler through the cogs, it should pass through the points of the teeth of both pulleys. That's the goal. If its the derailleur body, trying to bend it back may make it worse, but given the problems you have, I'd try. Worst case, hit your LBS for a new one before the race. – zenbike♦ 3 mins ago
Thanks a bunch. If you'll edit your answer to include the latest conclusions, I'll be glad to accept. – Stephen Touset 1 min ago


Help with identifying the brand of a vintage bike I've been trying to find out about the provenance of a vintage bike.

It is fitted with:

a USA Sturmey Archer 4 speed FW.63
Wagner Werdermann front hub
The brakes are Weinmann.
Cranks are Williams.

The wheel chain is either a triangle or a pine tree.

On the frame, there is a double ram horns

Wheels are 27x 1 1/4 or 32-630

And on the fork, there is a light bracket.

The plaque has been removed.
No markings anywhere visible.

It seems to be hand painted.

It looks better than in the pics.

Thank you for your help!

I might have found its provenance from the net.
Pinterest lugs

Amstrong.

Your points of views?
Thanks


New rocky mountain soul 29 making creaks by the bb Not to sure what it's coming from I don't have the tools to take the crank off or adjust the bb. The funny thing I don't get is that the creak is gone the next time I ride my bike then when I may go over a root or something and hour and a half into my ride the creak comes back then get progressivly worse the more I pedal. Then the harder I pedal the sounds gone. The lighter I pedal the sounds there. Th e only side it comes from is the left. I dont get it at all. I'm. It really bike inclined which is odd since I work as a vehicle mechanic. Any one have any suggestions.oh and the bb is a shinamo un-26 sealed square tapered bearing. And the bike is 2 months old

The crank arm is most likely loose on the square shaft BB. Remove it, clean it, grease it and retorque it in place.


What alters the efficiency of (cantilever) brakes? I have installed on my bike brand new cantilever brakes (Shimano CX-70).

On the rear, the braking is justas efficient as I would have expected it to be.

But on the front, it feels quite weak. Front braking is usually more efficient that rear but in my case it is not. Actually, stopping by using only the front brake would take very long. It is just powerful enough to maintain a low speed in downhills or increase the braking power of the rear (I get a little more power when squeezing the levers from the drops position).

But obviously the rear braking can only be as much efficient as the rear braking can get, with the limitation of all the weight and traction concentrated on the front that should make it the most efficient brake.

Obviously I checked the installation of my brake:

The pads are in perfect condition
They get in contact with the rim about 1-2 mm from the very top of the rim (and the beginning of the tire)
they have a < 2 mm clearance between rim and pad and that distance is the same on both sides
I installed properly a cable stop (http://www.aspirevelotech.com/images/Paul%20Components/041-FunkyMonkeyFrontCableHanger-Black.jpg)
the cable condition is very good, as is the housing and it is properly lubricated

What else could it be?

For the record, the rims are also in very good condition and I do know that the brakes are not exactly the same model on the front and the rear and yes I have purchased the right versions and yes the front is installed in the front and the rear on the rear.

I mean, I could understand that the brakes are crap, but in that case a similar model would not be working properly on the rear. So even if the whole mechanism were just exactly operating the same as in the rear, I would get at least as much and probably even way more efficiency on the front.

I just don't understand.

I have had similar problems in the past, and I would group them in these "categories":

Your rims are different. One of them has a smoother surface, or a different alloy, or a different quality alloy, and the actual friction is lower in one of the rims. I have this problem currently with one of my bikes;
One pair of brake pads is different. It can be from a different batch, or different model, or different brand, or different material, etc.;
If your pads are the (very common) asymmetric type, THEY SHOULD ALWAYS HAVE THE LONGER SIDE POINTING BACKWARDS! Everytime you brake, the pads tend to rotate "outwards", pulled by the moving rim, and that's why it's always best to assemble the pads with the longer side pointing backwards;
One or both of your brake bosses (and overall bike structure) flex when you brake. Specially on the front, where the "rotating outwards" can combine with the (carbon?) fork "opening" while braking. This is very successfully solved with a (somewhat infamous) "brake booster";
There are some possible geometric tunings, but this specific model doesn't seem to allow for tuning the pad position or the straddle cable length. If that were the case, attaching the pads away from the brake arms (thus widening the angle between the arms) and increasing the angle of the straddle cable gives the best mechanical advantage;
The pads have not burned in yet. Going for a tough ride, with long descents and possibly some dirt, could allow the braking power to emerge;
The braking surfaces keep being contamined by some non-cycling-related influence in your house: car exhaust near the front wheel, use of some spray product near the bike, oil coming from some wierd place, etc.

I hope this helps!


Damaged pedal threads on crank arms, having a hard time finding a replacement, what do I do? I have the Vitus Nucleus 27 vr, but I recently broke the original plastic pedal on it after I hit a rock and so I replaced it with another set. The problem is I completely overtightened and damaged the thread on both cranks.
I need to replace the cranks, however every website I try to buy just the cranks, I am met with either having to buy the whole crankset or just being able to buy the left crank for some reason. Also I'm very concerned about the compatibility between all the components.
So what do I do?
Thanks in advance.

You might be able to rescue the threads in the current crank with a thread tap.  Running the correct size back through the damaged threads might clean them up enough to work.
Failing that your LBS should be able to give you a price to Helicoil them.  Basically they increase the size of the hole and stick an insert in for the pedals to screw into.


Problem with chain `skipping` (but not trying to shift) I have two bicycles that suffer this problem, both pretty heavy frames (one a ladies, Hollander bike, and the other a man's commuter) - both have correctly adjusted Derailleurs which don't produce any noise or rub on the chain during normal riding.

However with both, on flat ground, at nominal speed - once every 3-10 revolutions of the chain it will simply skip; there's no drive for a quarter of a turn and then everything is OK.

I had originally assumed that this was a misalignment, or normal chain-skip (as I had only noticed it under heady load, cycling hard out of the saddle. However noticing the same happens on my girlfriend's bike, and on mine when I'm taking it easy disconcerts me, and leaves me with little confidence in the bike.

I'm not sure where to start diagnosing, however I suspect that stripping the drive train might be a start… perhaps also examining the chain for nipped-links, and the sprockets for damaged teeth (although, both bikes have a bash-guard on the front sprocket)

Any help or advice greatly appreciated, I'm a pretty handy motorcycle mechanic, but I always found working on my Human powered bikes a lot more fiddly :)

It turns out that it was a stiff link, stripping the chain off the bike, dousing it in brake cleaner, then oil and leaving it to bathe a few minutes, then repeating the process left the chain rust and dirt free, looking like new.

When I took off the chain, I broke it at the stuck link (which was clearly evident going through the derailleur when pedalling the bike backwards) -- cleaned everythingh whilst I had the opportunity and reassembled.

Whilst the chain was off, I did measure it, and things were within tolerance, although (I assume naturally) a little stretched.

Thanks for the help, I now have again a reliable bike!


How can I tell which size chain my bike uses? After learning how to break a chain and reattach it, and also how to add and remove a master link, I find that I can now do much more in the way of maintenance at home. I'll no longer need to bring my bikes into the shop simply for a new chain... if I can only figure out how to identify what size chain I'll need to order.

Is there a simple way of telling what size and type of chain I'll need to order to replace the chain on a bike? Do I measure the chain links? Count links? Count gears on the cogs?

If it helps, some of my bikes' drivetrains have internal hubs, some have derailer gears.

If you are using a bike with a derailleur the number of cogs on the rear hub will determine the chain size you will need.  They are always 3/32" chains.

You can get a 5/6/7-speed, 8-speed, 9-speed, or 10-speed chains.

If you can't find a chain that matches your cluster pick a chain for a larger number, for example if you have an eight-cog cluster you can use a eight, nine or ten-speed chain, but you shouldn't use a 6 or 7-speed chain.

Internally geared hubs will have their own specification for the size chain they require, and single-speed, fixie, BMX bikes, and probably some older bikes use 1/8" chains.


Over-tightening a BB I just installed an external bottom bracket (Hollowtech II type) on my steel bike. The manufacturer (Sugino) prescribes a 40-50Nm torque. I own no torque wrench, so I just wrenched it on pretty tight. Later on I came to bright idea to stand on a scale whilst I pull the wrench, and compute from this the exerted torque. Turn's out I've put a bit more than 50Nm on the cups, not sure how much more though. Would it be fine to leave it this way, or should I loosen the cups and redo the installation?

In other words, can over-tightening an external bottom bracket do harm?

I don't think anyone uses a torque wrench for installing the cups. If you did any damage, it would be to the threads of the BB or to the threads on the frame. However, unless you were an ogre when you tightened it down or you cross-threaded it, I doubt you did any damage. I do hope you used grease/anti-seize though, since you may ruin the threads if you didn't. You could also have damaged the spacers for the BB, I suppose, but it'd have to be pretty mangled if it affected the chainline and Q-factor significantly. So, if its this which you're worried about, I'd just leave it. Given that you have a Sugino crank, I'm assuming you probably don't have spacers.

When you're installing the crank, theres a cap you have to put on -- this only requires something like 0.5 Nm. If you overdo this, you'll load the bearings such that they wear down faster. If you've overtightened this, you need to undo it. Same with putting the non-drive side crank arm (which is something like 15 Nm normally).


Why don't race bikes have solid front triangles? I know that cutting material out makes a bike lighter, but at some point there must be a crossover between weight and aerodynamics. Since tri-bikes and track bikes have more oval/flat shaped tubes, you'd think that closing off the entire front triangle would improve aerodynamics even more. And making it out of carbon fiber wouldn't add too much weight. See also the use of enclosed wheels.

So, outside of the obvious reasons of weight and the loss of a bottle cage, why wouldn't you want to do this?

Much of this is due to UCI regulations. They specify what shape and size of frame can be used. It is not allowed to add extra parts just for improving aerodynamics.

See the UCI document Technical Regulations For Bicycles - A Practical Guide To Implementation (PDF) which covers most of this.

As it says for Article 1.3.020, the frame elements must be tubular, with a maximum transverse dimension of 8 cm and a minimum transverse dimension of 2.5 cm, in a maximum ratio of 1:3. Also Article 1.3.024 "Protective screens, aerodynamic shapes, fairings or any other device that is added or forms part of the structure, and that is destined or has the effect of reducing wind resistance, are prohibited."

It could be possible to make a more aerodynamic bike that was not allowed by the UCI. But you would be restricted by what races it could be ridden in. A few brands have mode non-UCI compliant race bikes, mostly designed for triathlon. eg some versions of the Specialized Transition or Shiv, which have extra aerodynamic tubes etc.


How to determine size of freewheel? My previous question was: How to take apart this rear BMX hub?

How do I determine the size of my freewheel to replace it?
I have seen on bicycle sites that a freewheel comes in sizes like 14t, 16t, 17t, 18t.

Here is a picture of my freewheel. It does not have any markings or inscriptions. The freewheel diameter of the ring, not the cog teeth is 55mm.

the 14t, 15t, etc. is the number of teeth. You currently have a 16 tooth or 16t freewheel. More teeth and the easier to spin, but the slower it spins. Think of teeth on the rear cog as inverse to ease...lower numbers take more power to move; higher numbers take relatively less power. You want to find a good mix that allows you to make it up whatever hills you have while still not requiring a super high cadence for the flats.


Mechanical-hydraulic hybrid brakes I've heard about Mechanical-hydraulic hybrid brakes but didn't find any examples.

Are they exist? If yes, are they comparable with hydraulic?

Looks like the TRP Parabox Hydraulic Disc Brake is what you're referring to.  Basically it allows you to use your existing mechanical brake levers to control the hydraulic pistons.  So you can use your old brifters, and still have hydraulic braking.  Here's a review that explains how they work, as well as provide and idea of the performance characteristics.


Front derailleur adjustment question: what to adjust I'm a bit confused about what's going on with my front derailleur (which is PROBABLY a Shimano Acera, but the bike is 13 years old and the name has long since rubbed off).  The chain has started rubbing against it when it's in a hard gear on the 3rd (largest) chain ring.  This is the 8th gear.

If I adjust the barrel adjuster until the chain just stops rubbing, then it will invariably rub in the 5th gear.  Previously, the bike was able to work without the chain rubbing until I got into the 3rd gear.  If the barrel adjusters aren't working anymore, what might be the issue?  Is it just a cable tension issue that's too far gone for the barrels to fix?

If I were you, I would first get new cables and maybe even housing for the derailleur cables. Put the barrel adjusters in sort of the middle and change the cables. If it's still having an issue, then the problem might lie in the upper limit of the derailleur. Check the limit screws on the derailleur and loosen the upper one.


Left pedal coming loose On my bike, which I just built out of spare parts, the left pedal seems to constantly be coming loose. It seems to come out about 5m every time I ride ~10km.

It's an old cotter pin crank, and the pedal is a left pedal (there's an L stamped into the end of the screw that goes into the crank). The pedal has a crack in one side of the axle compartment, but I don't think that would affect it.

I thought that these pedals had left-hand threads so that the action of pedalling would work to tighten the screw? If so, why would this be happening, and is there anything I can do about it short of replacing the crank and pedal?

What I'd do:

remove the pedal
thoroughly clean the pedal threads
thoroughly clean the crank threads
let both dry
apply 2 drops of thread locker on the pedal threads (e.g loctite blue)
fasten pedal on the crank well (e.g 40 Nm)

If it comes loose after that I'd temporarily try another left pedal just to find out whether the pedal or the crank arm is problematic.

Before step #5 you need to inspect:

try to see whether the threads of pedal or crank look worn
screw pedal in crank by hand (or tool without applying a lot of pressure) until the end
was the threading smooth until the end?
does the pedal have any serious play within the crank arm? (which can only be eliminated if you screw the pedal very hardly in?)
if yes, then the threads may be worn

Sometimes people screw pedals in crank arms with no care or patience and the pedal may not be positioned correctly to be screwed all the way in because its threads overlap badly with those of the crank arm.


Which is ideal road-bike size for a person with height 5'9.5"? I am 5'9.5" and in seam length between legs is 33 inch. What is the optimium frame size?

Ten thousand expert opinions can't match a single objective test. I'm about your same height and inseam. I have 52cm, 54cm, 56cm, and even a 51. They all fit, and work for me. One manufacture's 54 will sometimes feel like another manufacturer's 56cm. Fit isn't just about frame size. Stem, saddle position, spacer count, all play into it. Ya gotta test ride a couple of different makes and sizes. If you're like me, you're gonna want to write your findings down on paper to review once the "wow, that was cool" factor wears off a bit.


What is the correct kind of hitch receiver that works with my bike rack? I have recently placed an order for this bike rack and if you scroll down to the Features section you will see it says it requires the following type of hitch receiver:
Hitch Size: 2” only (Do not use a 1.25”-2” hitch adapter)

From UHaul's list of available hitch receivers here: https://www.uhaul.com/MovingSupplies/Hitch-Receivers/
which one should I get that will work with the bike rack I placed an order for?

As Daniel R Hicks writes, any sturdy 2" receiver hitch should work, ** as long as it fits your car **. Hitches are usually specific for one or a few car models.
Hitches are designated according to the width of the square receiver opening. 1.25" hitches are typically lighter than 2" hitches, but are also less robust and can't support as much weight. Since you are getting a heavy-duty rack to carry heavy e-bikes (80 lbs/bike max vs. 35 lbs/bike max on a "normal" rack), you need the strength and weight capacity of a 2" receiver hitch.
As mattnz notes, a bike rack slotted directly into a hitch receiver will generate higher torque forces on the pitch axis (rotating forward/back) than would be the case with a standard tow ball/trailer combination. The hitch needs to be even beefier to withstand these higher torque forces.
The hitch specifications will probably indicate a maximum "tongue weight" which is the maximum weight pressing down on the end of the hitch that it is rated to hold up. The larger the tongue weight rating, the better, as the weight of the rack and bikes will essentially be tongue weight.


How can I prevent cars from passing me too closely? Recently, a driver buzzed by me, leaving just a couple of inches between my handlebars and his car. It was very scary.

In general, how can I prevent cars from passing me too closely?

Please cite sources.

Use proper positioning. This is most important. Unless the outermost lane is as wide as two SUVs, ride in its center. When it's safe, reasonable and necessary to let drivers pass, kindly move over; but always leave at least 18 inches (0.5 m) between you and the curb. The driver behind you may have to wait a minute or two, but they'll survive. If they've waited a few minutes, be nice and pull over. (Adapted mainly from Wikipedia citing Cyclecraft.) Paradoxically, correct positioning will stop most drivers from buzzing you. Correct positioning can be scary, but does get easier.

There's more to vehicular cycling. You must read more about lane release. Also read "Street Smarts" online: either the American edition or left-hand-drive edition. If you want, you can also read Cyclecraft, or take a class, or watch some videos. (Can anyone recommend some videos?)

On rare occasions, drivers may still buzz you. To prevent this:

Use a safety flag. A spring-mounted one: e.g. a Flash Flag. (Source.) It must be spring-mounted, so that it can bend easily if hit. (If you can't afford a flag: Maybe you could use a dollar-store pool noodle plus a washable marker pen. See here.)
Or use a doll. Put a baby-sized doll in a trailer or rear-mounted carrier.

About attempted murder: If a driver ever intentionally endangers your life, note down the license plate number, location, time, and date. If you value your safety, don't touch the driver's car. Contact a cop: preferably immediately; but better later than never.

This post is marked as community wiki. Please add to it.


Why is my electric bike 'clanking' under load? I have a Giant Esprit Twist Power electric bike, which apart from not having nearly enough words in its name also has a problem related to the crank.

When I put a lot of load through the pedals there is a loud clanking sound, once per pedal-press. If, as I cycle, I press with just one foot (and just lightly follow-through with the other) then I get the noise once and then not again until I start pressing with the other foot. This suggests to me that the problem is related to something shifting position in response to the side of the bike on which the pedalling force occurs.

Curiously, although the noise is extremely pronounced, I don't think I can feel anything.

There is no play I can feel in the bottom bracket, and likewise the pedals seem to spin smoothly.

The torque-sensing chainset arrangement seems like a possible source for the noise, I'm just not sure how.

So I guess my questions are...

Can a bottom bracket bearing make this kind of noise without feeling rough or loose?
Does anyone have any advice to offer about this kind of torque plate?

Here is a picture of the dismantled torque-plate:

Thanks in advance!

That crank is unusual and therefore it is hard to give you advice.

It shouldn't be the bearings because they don't usually make a big noise, but
rather make the crank harder to move around (you can perfectly feel bad bearings if you try moving it with your hand and feel resistance/side-to-side movement).

Can you install the crank without the clutch mechanism, or simply install another crank, and test if the noise goes away? My bet is it will :)

If the noise goes away, the best is to contact Giant support or a representative and see what they can do for you (send you new pieces, help troubleshooting, etc). If they can't do anything for you, at least ask them to advise on a solution, or to suggest a list of cranks that are compatible with the electric system, in case a normal crank does not work.

While testing keep in mind this can be a malfunction piece which might fail to perform at the worst possible moment, so take it easy. Good luck.


Problems with cheap housings So, I converted my road bike from downtube shifters to STI brifters, and I noticed that the cable housings don't sit properly in the downtube cable stops, do you think that would be a problem ?

EDIT:

Yeah, I think that the housings are for brakes.

I think it will work fine for a while, but the slight angle will increase friction and therefore wear on that point of the cable.  This will make it harder to move too over time.

Water from rain or road spray will rust in there a little faster, and this can result in the housing popping out of the retainer easier.

I'd suggest using some calipers to measure the ID of your mounts, and the OD of your cable, and find a suitable end-cap/ferrule to fit.

Consider asking your LBS - Any good shop has drawers and boxes of little components like laying about.

Another bodge might be to find some thin-walled plastic tubing like garden irrigation pipe and fit a short piece over the chromed ferrule already installed.   I'd not recommend tape as a solution because it tends to mush, and helps hold water.


Ultrasonic cleaner power requirements, for cleaning chains before waxing This question is a follow-up to Ultrasonic cleaner advice, for cleaning chains before waxing.

I plan to lubricate my chains by immersion in molten paraffin wax. The advantages and disadvantages are discussed in answers to a question by Poulter.*

The wax only adheres to clean surfaces without grease. While this is easy to achieve that for the outer surfaces, it is not easy at all where it counts: inside the roller bushings. I should rather avoid the good old Sheldon Brown method, since I fear it may be too much fun†. It appears to be consensus that ultrasonic cleaning is needed.‡

In JC Allen's answer to Ultrasonic cleaner advice it is pointed out that heating is necessary – 50 C are suggested. An answer by Maarten discusses cavitation size at lower ultrasound frequencies.

However, there is no discussion of the transducer power requirements to achieve thorough cleaning between rollers. At present I am in a discussion with other cyclists who doubt that low powered devices, specifically a 2l device with a 60 W, 40 kHz, transducer is sufficient.

What are the requirements for a ultrasonic cleaner? What is the minimum transducer power for thoroughly cleaning all relevant surfaces?

* Please post fundamental comments on the method at Poulter's question.

† Fun, as in the feeling experienced when one's dwelling is flooded with magma, while being inside.

‡ I cannot find sources to support that claim.

tl;dr: Are heated ultrasonic cleaners with low powered transducers (e.g. 30 W, 50 W, or 60 W) good enough for cleaning bicycle chains from lube before paraffin wax treatment?

Probably not, especially if some of that power is shared with heating, which may not be mentioned in a straightforward manner in the product description. According to Adam Kerin of Zero Friction Cycling, small jewellery cleaners won't cut it either, and there is also the possibility of getting a too strong cleaner that may damage the chain. Nominal transducer power is 70-120w, although no mentions of frequency are made. More specifically:

  Like all things there is a right tool for the job. A jewellery cleaner is likely not
  powerful enough. I have had customers using auto parts cleaner at work that have
  pitted chain metal – this would stripped low friction coatings and plating’s off chain –
  too strong. Somewhere between around 70 to 120w max cleaning power is about the
  right cleaning power for bicycle chains. Note this is not total power consumption – a
  US cleaner may use 100w but only 35w of that is cleaning power – check the specs.

Additionally, you can preheat the water and use a kitchen thermometer to get to a good temperature range, saving a lot of time from waiting the cleaner to heat the water. This is also mentioned in the same document.

Source: https://zerofrictioncycling.com.au/wp-content/uploads/2018/10/Ultrasonic-Clean-Race-Chains-Quick-guide-v3-converted.pdf


When to replace a tire? I was repairing a flat on my rear tire today and noticed that the tire has started developing a flat area on the tread (see the photo below, it is the one on the right). The tire is a Continental Ultra Sport. Comparing the rear with the front there is an obvious band about 10-12 mm wide around the circumference of the tire where it contacts the road. The front tire still has a more tubular shape (little or no flat band).

My goal is to understand what this is telling me about the bike (significantly more load on rear tire?) and how I ride it and also to understand better when the tire needs replacement. For the latter question I'm primarily concerned with the reliability of the bike – a lot of my riding is for transportation and I'd like to minimize flats.

Yes, it is time to change that tire!

Your current front tire looks to be in very good shape so when you purchase a new tire you should put it on the front wheel and then move the old front tire onto the rear wheel.

Continental road tires have helpful wear indicator dots on them that will show you when the tread of the tire has reached its recommended replacement point:

There will be two of these indicators on the tire, one on each side of the tire's center line. Note, they are not always quite this close together. Many other brands will also have such some type of indicator marks on them, especially road tires and other tires with no to light thread patterns.

For other tires there are some general rules you can follow on when to replace a tire:

You start experiencing a sudden increase in the number of flats received in a tire and there are not good explanations for the flats.
The tire has worn down to the point the casing has started showing through the tire.
On bikes where your tires have noticeable tread pattern (mountain bike, cyclocross tires etc.) and the tread pattern has worn down.
You have a long, wide flat spot along the centerline of the tire, such as in your photo. At this point you may also notice your speed has dropped of slightly and that cornering may have gotten a little squirrelly.
The tire has cracked rubber, either due to the age of the tire or mistreatment such as improper storage or consistently riding on the tire while it was under inflated.

Some people will try to give out general milage estimates of how long a tire should last but these tend to be pretty useless as your tire's longevity depends on the type of tire, your riding style, your riding conditions etc.

It is typical for rear tires to wear more quickly then the front tire. I have always attributed this mainly to the fact all your starting force is applied to the rear wheel hence any wear due to friction while starting and accelerating is experience on the rear tire.

This answer to the question 'why does my back tyre wear so much more quickly than the front?' also postulates increased deformation of the turning rear tire  results in more wear due to the sliding of the tire that occurs during the deformation process.


Sidewall cut on brand new tyre - permanent fix possible? I bought a new set of tyres (Continental Grand Prix 5000). Being an idiot, I managed to cut the sidewall of the tyre with a knife while removing the packaging.
I have looked at repairing it, and came across items such as the Park Tool TB-2 Tyre Boot. However, I noticed that these fixes are only meant to be temporary, and not permanent.
Is it safe and advisable to use a tyre boot to repair a new tyre which I plan to ride 3000-4000km on, or do I need to cut my losses and just buy a new one?

No, a tyre boot will absolutely not be enough. Some side cuts are repairable by stitching. However, it is better for MTB tyres that use smaller pressures. I do not know if it is likely to work on a road tyre.


How to clean a bike after muddy/sandy cyclocross race (or mountain bike ride) What do I need to be concerned with when cleaning my bike after a typical muddy and sandy cyclocross race? (Probably also applicable to mountain biking.)
Particularly, what can be done (in the field) between races to keep the bike clean and ready to ride again? Also, what am I missing due to the quick cleaning which I should take care of at home later?
I know we are supposed to avoid using a high pressure washer around the hubs / bottom bracket to avoid pushing out the grease.
I'm concerned with

Grit in the chain
Grit in the brake cables / shift cables
Grit in the brakes and on the rims (typically canti-brakes)
Mud caked in and around every part of the drivetrain / hubs / derailleur
Re-lubing the drivetrain (and other parts) for another race
What kind of 'field kit' items I will need for this

Other Related Questions on bike cleaning:

How to wash a bike properly?
How can I clean sand off my bike chain?
What to use to clean your chain (and cogs)?

You should definitely be careful with it, but at many races we employ the use of a pressure washer to do broad stroke cleaning like getting mud, grass, etc off the bike and tires. You need to be careful and use it from a little distance and obviously not get up close on the BB, hubs, etc. but it does a good job of initially cleaning or cleaning between races.

After the race you should do more appropriate maintenance on the bike with degreaser and proper lubes.


How should I set up my rear shock (with ProPedal) to minimise bob when climbing? I've got a Fox RP23 rear shock which I'm very happy with, apart from the apparent ineffectiveness of the ProPedal setting.  Bob is very noticeable on climbs in both positions.  It's hard to say which is better.  I don't expect to eliminate it completely, I just want to know that I've got the optimal setup for my bike and riding style. The manual is pretty vague so I'm wondering if anyone has any useful tips?

Pro-Pedal provides bob resistance when on, 1 being lowest.

Try this.  Pull out the numbered knob and position it so that "3" is in line with lever.  That will give you the most Pro-Pedal.  Now, try riding up a hill with it off and again with it on.  You should notice markedly less bob with it on.  If not, I might take it to a shop to make sure that it is working.


Sigma 14.16 STS screen barely visible Around 4 months ago, I bought a Sigma 14.16 STS computer for my bike. I rode around 2500 km since then. Everything work perfectly until yesterday, when the computer just (almost) stopped displaying. What previously was a normal display, now has a couple of lines which change when pressing buttons, indicating that something is happening there and the computer itself works, but I still can't see anything. The thing was never put into extreme conditions (never colder than -8, never hotter than +20), I didn't try to drown it (even though it is waterproof and I used it in rain), didn't smash it against the ground (it never fell). Just the screen started malfunctioning. Anyone else ever had such a problem? What could be a fix?

Several reason come to my mind:

The temperature at which you were using it. LCD displays get notoriously slow at low temperatures. You mention -8°, was it right then when this happened? Things should go back to normal at room temperature. The computer will still be working normally but the display literally freezes. The phenomenon is well known to people who own an early LCD wristwatch. They became unreadable in the cold.

At low temperatures, the battery either 3V lithium CR-type cell or Li-ion rechargeable slow down because of chemistry slowing.
If the battery is a CR-cell it might be reaching the end of its life. Your device may be new but the battery was already inside for a while when you bought the computer or the cell is faulty.Try replacing the battery.

But then since your device is quite new I'd advise you to take it back to shop who sold it to you as warranty is still applicable.


Other than chain length, what are the limitations to the number of gear teeth? I need to replace my chainwheel and cassette, and it made me think. I know that the chain has to be a specific length relative to the number of teeth on the gears.

I was thinking about changing the cassette for one which a bigger 1st gear. Suppose I could get one with whatever number of teeth I wanted.

The bigger the better, right? If better means less effort to climb hills. But I have never seen a really big gear, like almost the circumference of the wheel.

I assume that's for a practical reason, not just because it would be very lazy if it worked and look ridonkulous :)

In the diagram below (from Park Tool) one can notice that if the innermost (lowest) cog grows much larger it will interfere with the top pulley on the rear derailleur. This is the primary limiting factor for the size of cogs.

(source: parktool.com)
For chainwheels, I suspect that the ground would be the physical limit (for a typical diamond frame, anyway).  Of course you'd better eat a good breakfast and have a friend with a shed on his car if you plan to turn a ring that big.


Can I tell the inner diameter of my 1" head tube without removing the headset? I need to replace my 1" threaded headset, but to my surprise the replacement headset is available for either 30.0mm or 30.2mm inner head tube diameter. Is it possible to tell which one I need without removing the headset cups?

Probably not.
Knowing the manufacturer of your bike gives a clue but not always definitive.
One is the Italian size and more common. The other is Japanese.


How to decelerate during long downhill rides and avoid brake glazing I mostly ride touristic style, and its not uncommon descents of few hundred meters or even 1000 meters (vertically, usually average gradient is around 5-10%). What's the best technique to brake to avoid glazing of brakes?

Theory

I've heard following advices:

pulse brake instead of constantly braking
use alternately front and rear brake
create as much of aerodynamic drag as you can to reduce the pressure on brakes

Apart from that, I have following theories:

brake pads have some temperature above which they will start to glaze, so I should brake in such way, to avoid exceeding this temperature
if I brake suddenly with great power, brake pads/disc rotors/rims will have to absorb a lot of energy which translates to heat, if I brake gently - less heat is generated
if I brake with both brakes energy will be divided between two brakes so as heat (though not necessarily evenly - division depends on the force applied on brake levers)
the greater the speed, the greater aero drag, so if I go faster, less energy (in total) will need to be absorbed by brakes
the lower the speed, the longer the time that it takes to ride, so longer the time to dissipate the heat from brake system

Braking strategies

So based on all above I have two strategies for braking:

Brake as little as possible, but when needed (ex. before hairpin turn) brake shortly with great power and both brakes
Brake constantly using both brakes and maintain low speed (below 20km/h?)

First strategy is trying to use as much aero drag as possible and then it will generate a lot of heat in brake system. Though during the brakes it will have time to cool down again. Second strategy maintains constant high temperature of brakes, but provided low travelling speed I assume that temperature will not exceed glazing temperature.

These strategies I discarded:

Brake constantly and maintain low speed using alternating brakes. This means that although the brake that's not operating is chilling down the other gets full load and its temperature will be higher improving risk of exceeding glazing temperature.

Experiences

I've already glazed a few disc rotors:

In my commuting bike, I have one hill (700m long, 4% gradient), and I brake shortly but with great force
In my trekking bike - downhill on straight asphalt, starting with gradient above 10% where I gained ~50km/h later I tried to not gain any more speed using alternating brakes technique

Also I have a feeling, that after glazing, when I experience lower braking strength, if I ride a few downhills when I'm more gentle towards this brake it regains its effectiveness. Is it possible?

Though it might be problem solvable using different means (reduce my weight, use larger rotors). I'm looking that would work best, even on non-disc-brake bikes.

EDIT:

Final Question

To reduce number of variables, my final question is:
Given:

The speed Vn - which is the speed the biker would get if he would not brake nor pedal at all, when areo drag is preventing him from gaining any more speed from gravitational force.
Desired speed the biker would like to go Vd = R * Vn

What are the optimum braking strategies that:

Minimize time that it takes to ride 10km of such slope
Prevent brakes glazing

Depending on the R. If R >= 1 then the strategy is just not to brake at all, that's easy, but how to brake if R=0.5 or even R=0.1?

Brakes work by turning kinetic energy into heat through friction. As you heat up the system there generally is less capacity to absorb more heat (in addition to physical changes  in the brake system component).

Constantly dragging your brakes is probably the worst strategy. Tandem bikes do this but they typically have one braking system dedicated to being a drag brake, and a separate braking system to be used for stopping. If the drag brake fails from overheating the primary brake system should be unaffected.

The reason constant drag braking is a bad strategy if you do not have a dedicated drag brake is as follows:

The brakes never get a chance to cool off, building up heat over time which can make them ineffective if for example you need to suddenly stop;
If you are drag braking to maintain a slow speed then you are not taking advantage for aerodynamic drag. Drag goes up with the cube of velocity. As such you get the highest braking force from aerodynamic drag the faster you go (yes it does sound crazy).
If you are not effectively using aerodynamic drag you are forcing your brakes to do proportional more work (i.e., heat) than if you let your speed run up then brake.

Depending on your tolerance for speed (I am personally happy running my speed up to 90+ km/hr), the optimal strategy is to let your speed run up, do a period of braking where you drop your speed down (e.g., go from 80 km/hr down to 40 km/hr), let off the brakes and let your speed run up. This lets you cool off your brakes as well as use aerodynamic drag to your advantage. The key is to try and have long periods between a braking bought so you can get as much heat out of your brakes. If the period between a braking bought is too short (e.g., pulsing your brakes) you will start to get excessive heat build up in your brakes eventually leading to fade and even failure in some extreme circumstances.