Česky English

Cranks and pedals

Pulling cranks off a square tapered axle is the hardest work you can find on the whole bike. First, they are usually pressed in so tight that a crank puller can't pull them off even if it didn't strip the dustcap thread (which happens quite often). Second, they are hard to grab because they tend to be slippery, round, five-armed and obstructed by a bunch of frame tubes. Fortunately we usually only need to pull the cranks off to replace a worn axle, so it doesn't matter if we destroy it in the process. My favourite system is to carefully cut the axle with an angle grinder (a thin grinding wheel just fits the gap between bottom bracket and crank) and tap out the tapers gently and comfortably on a workbench. If you want to keep the axle intact, your only choice is to alternate tightening the puller and hammering over a block of wood until the crank loosens, micrometre by micrometre. If you don't have a puller, you're left with a hammer alone (poor bearings). Or there is one alternative method: loosen the fixing bolts and have a ride, standing up if possible. With a bit of luck the cranks loosen after several kilometres and maybe their tapers survive it without damage (be careful with aluminium).

What's the conclusion of this? Only use square tapers together with maintenance-free sealed cartridge bottom brackets. Very old bikes or supermarket junk which combine tapers with simple cup and cone bearings are a really bad idea. And a conclusion #2: when you install such cranks, grease the tapers a bit, maybe it will help the uninstallation later.

But tapers are not the worst way to connect cranks and axles - there are cotters too. It is true the disassembly is usually troublefree (Usually. I had to cut rusty cranks to pieces once, good for them they were scrap anyway), but they tend to disassemble automatically over time. One face of a cotter is weaker than four faces of a square and it deforms gradually in normal use. For some time it can be remedied by retightening, until the cotter has to be replaced. Sometimes you can meet a junk bike whose cranks jump forward on every turn - that's what overused cotters look like.

Luckily there is a modern solution: splined axle. A crank fits on it with a comfortable play, gets fixed in place by a bolt and then another two bolts clamp it around the axle tightly. The only problem is the manufacturers don't cooperate much and each one's splines are different.

Pedals

What to say about pedals? Nothing special, just note that the left one has left-handed thread, so it screws into the crank counterclockwise. Pedals are quite simple, even the cheapest ones can work reliably for years. And unlike the bottom bracket axles, they all have the same threads, so replacement is not a problem.

Besides the classib pedals (an anti-slip platform you put your shoe on), there are also clipless pedals (the name is quite confusing because your shoes do clip in them, they just no longer use the old system of straps that clips around the shoes). Their advantage is your foot can't fall off the pedal and it can push or pull in any direction, which boosts your power considerably (especially with recumbents). The disadvantage is you need special shoes with cleats in the soles, and you need one extra ankle movement to unclip.

There are several types of clipless pedals, SPD (Shimano Pedaling Dynamics) is probably the most widespread one. Their only adjustable element is the rear hook tension. It must be strong enough to hold the foot safely, but weak enough to allow comfortable unclipping. I like a rather weak setting: I loosen the spring completely and then tighten it until I can't move it with a bare hand. Second adjustable thing is cleat position on the shoe, the optimal position is generally different for everyone (I have it as far back as possible).

There are combo pedals with a platform on one side and clipless mechanism on the other. It looks like a good idea, but the opposite is true. Clipless pedals need almost 2 cm higher seat, so you either have to re-adjust it with every change of pedaling mode, or to live with some uncomfortable and unhealthy compromise. So I'd recomment either platforms or clipless, but not both at the same time.

Ads: