justadude

Old (Williams f7) cottered crank arms pedals thread on for a few turns, and then stop threading. Right, clockwise. Left, counter-clockwise. My questions are: does it need different threaded pedals, or does it have damaged threads, and what can I do about this?

nlerner

You sure your pedals are English threaded and not French threaded?

justadude

I'm using Raleigh pedals marked "Made in England", and another set of Shimano R-70 pedals. I assume the cranks are English threaded since they're also apparently made in England. I suspect the problem is damaged threads. If there is a simple way to repair them, or have to find another set?

rhm

Inspect the pedal threads, inspect the crank arm threads; if you see any kind of a problems with either one, do what you can to correct it. The pedal threads are easier to get to, and more important, since the pedal spindle is a harder steel than the crank arm. But being harder steel it is less likely to be damaged. If there's rust or anything like that, clean if off.

Apply grease and try threading the same pedal on from the other side; see if it goes any farther. This may correct a minor problem. But don't force anything.

You can run a pedal tap (9/16") through the crank arm to clean it up. Your bike shop should have them. Worst case scenario, a bike shop can cut a larger thread and insert a helicoil to hold the pedal.

justadude

Thank you, rhm.

gmt13

I recommend to all that they invest in a set of thread gauges (see pic below). They are cheap and allow quick assessment of what your dealing with. You can find them for less than 5 bucks. French pedal threads can show up on cranks of English manufacture (and vice versa). French pedal threads are 14 mm x 1.25, which is real close to 9/16 x 20 tpi, so be careful. I think that it's possible to retap French threads to English, but why do this if you don't have to.

justadude

I found the French thread pedals were a smaller diameter. I concluded the crank arm threads were English, but cross-threaded by previous owner. I determined there was no better option, so I forced the pedals to thread in using a wrench, and they are now tight in the crank arms.