Where can I get information on the various different types of threads used in bike pedals as each manufacture has its own specifications? Different manufactures of pedals have different threads and I need the design and specification for the pedals to not strip the threads, etc.
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2Fortunately pedals are one of few things on a bike with basically one standard that everyone plays by.– whatsisnameCommented Jun 11, 2015 at 5:11
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1 Answer
Just about all pedals for bicycles will use the same threads. According to Sheldon brown the standard size is 9/16" x 20 tpi threads. One piece "American" cranks use 1/2" x 20 tpi threads, but these are only found on low end bikes and children's bikes. There's been a couple other sizes used in the past, but almost all modern bicycles will use the two above sizes.
It's also worth noting that the left hand pedal uses a reverse (counter-clockwise) thread to prevent it from loosening on it's own when pedaling. The right hand pedal uses a standard (clockwise) thread.
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1Even low end stuff these days will use 9/16" x 20 tpi. The only case which you might encounter which is not low end is old French stuff, which is just slightly different enough so that you think 9/16" x 20 tpi will work, but it won't.– BatmanCommented Jun 10, 2015 at 18:04
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@Batman I think you're right. Now that I think of it, even the lower end bikes that I've seen recently seem to have 9/16" inch pedal threads. Perhaps I'll check the pedals on my kids' bikes and get back to you on that. I was kind of just going from the information on Sheldon's site, which can (understandably) be a little dated in some areas. Also, Sheldon mentioned the now defunct "Dyna Drive" system which used must larger thread I think if you're designing a pedal or crank arm, you would pretty much cover the entire market by just going with 9/16".– KibbeeCommented Jun 10, 2015 at 19:25
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Well for esoteric things like dynadrive chances are the owner knows already that they have something weird. Buying old french bikes isn't too uncommon.– BatmanCommented Jun 10, 2015 at 20:01
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@Blam Read the part in the link about "precession". The purpose of the reverse threading is to prevent the pedal from coming loose. This was an actual problem people had way back before they started using reverse threads. The pedal bearings would have to be beyond messed up for the bearings to lock up enough to cause it to unscrew. I don't think I've ever seen bearings that bad. Most pedals would have been replaced well before then.– KibbeeCommented Jun 11, 2015 at 11:01