Pedals to Crank arm sizing
Are there different thread pitches and shaft sizes to pedals and crank arms, or is it universal? I'm winding up with crossed/stripped threads. When I search on google for crank arms and pedals, they always come separate. My pedal fell off, the threads were all stripped inside the crank arm. I put a new crank arm on with the same pedal, and I coiuldn't get the pedal on the crank arm without crossing the threads. How do I stop this from happening?
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PS, I may have mixed up the left/right crank arms. What's the difference between the left and right crank arms?
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Right crank/pedal is normally right threaded. Left crank/pedal is normally left threaded.
Most common today are 9/16" x 20 tpi. On old one piece cranks and some other bikes 1/2" x 20 tpi is found. At various times, mostly with vintage bikes pre 1970, you'll find some different thread types and directions. If you mixed up the crank arms, it makes me think you may have one of those very old bikes that might have different threading's and directions. And maybe won't be compatible with any new pedals. Put a pic in the gallery here and someone might try to find it. Though you only need 1 more post and maybe a full day to be able to post pics. |
Originally Posted by damnbike
(Post 22502607)
PS, I may have mixed up the left/right crank arms. What's the difference between the left and right crank arms?
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Originally Posted by damnbike
(Post 22502607)
PS, I may have mixed up the left/right crank arms. What's the difference between the left and right crank arms?
Also--often the pedals themselves, usually on the axle, will be marked with "L" and "R." |
I've never tried, so I don't know...but could you even start left hand threads into a right hand crank, or vice-versa?
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Originally Posted by cxwrench
(Post 22502637)
Left and right threads. Hopefully you didn't damage the threads in your crank arms by forcing the pedals into the wrong threads.
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Originally Posted by smd4
(Post 22502639)
The right one has the chainwheels attached?
Also--often the pedals themselves, usually on the axle, will be marked with "L" and "R." I might have mixed up the pedals too :( I didn't know everything was different left and right. |
Originally Posted by damnbike
(Post 22502781)
I might have mixed up the pedals too :( I didn't know everything was different left and right.
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Originally Posted by smd4
(Post 22502647)
I've never tried, so I don't know...but could you even start left hand threads into a right hand crank, or vice-versa?
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If the threads aren't buggered up too bad, you might can run something through from the other side and straighten the threads enough to install the pedals properly. A pedal might do that if the treads are long enough to go all the way. If not you'll have a hard time finding something long enough that is left threaded.
However if you did not notice that things where right and left threaded or that you were cross-threading, then maybe you should go to a bike mechanic with this. DIY is better learned when everything is correct. Otherwise, you'll probably get some misconceptions right from the start that will be hard to rid yourself of. And still, we are a little confused about you saying you can swap left and right cranks. Are there any part numbers or brand and model stamped on the cranks? Again, how about putting a pic in the gallery and we'll look for it if you can't now directly post them in your replies here. |
Originally Posted by damnbike
(Post 22502781)
Well, this was on the chainwheel side, I replaced it with a spare, but I didn't know if the spare was left or right.
Is this the same bike that you're having trouble with the chain? |
Originally Posted by damnbike
(Post 22502780)
I did strip the threads on the crank arm, then put on a spare crank arm, and crossed the threads on that too :(
Originally Posted by smd4
(Post 22502787)
Look for the "L" and "R" stampings on the pedal axles, near (or on?) the wrench flats. The threads are different on the left so the pedal doesn't unscrew itself while you're pedaling.
Originally Posted by Iride01
(Post 22502811)
If the threads aren't buggered up too bad, you might can run something through from the other side and straighten the threads enough to install the pedals properly. A pedal might do that if the treads are long enough to go all the way. If not you'll have a hard time finding something long enough that is left threaded.
However if you did not notice that things where right and left threaded or that you were cross-threading, then maybe you should go to a bike mechanic with this. DIY is better learned when everything is correct. Otherwise, you'll probably get some misconceptions right from the start that will be hard to rid yourself of. And still, we are a little confused about you saying you can swap left and right cranks. Are there any part numbers or brand and model stamped on the cranks? Again, how about putting a pic in the gallery and we'll look for it if you can't now directly post them in your replies here. |
Originally Posted by cxwrench
(Post 22503060)
You mean 'something' like a tap that's sole purpose is to clean up threads?
But I guess if the OP needs to pay the tuition to DIY school, this is as good as any to incur those fees. |
If you manage to get old French pedals or cranks from the 60's or 70's, they're very close to the standard 9/16 pedals, and will cause all sorts of headaches.
As mentioned above, remember for pedals it is right side, right thread, left side, left thread. For bottom brackets it is just the opposite, right side, left thread, and left side, right thread (with a few more specialty variations than the pedals). I presume one of the reasons the threads get bungled is that people overtighten the left side trying to remove the pedals. Always hand tighten screws until you get several turns before grabbing for the wrenches. Sometimes turning backwards a couple of turns will help you orient the shaft before threading it in. If pedals have stripped the threads, then make sure the threads are super-clean before reusing. A good shop may be able to helicoil stripped crank threads, but for a cheap bike, doing so may be more expensive than just replacing the crank. Nonetheless, a good helicoil job should be permanent, and might be better than new. |
Originally Posted by damnbike
(Post 22502595)
Are there different thread pitches and shaft sizes to pedals and crank arms, or is it universal? I'm winding up with crossed/stripped threads. When I search on google for crank arms and pedals, they always come separate. My pedal fell off, the threads were all stripped inside the crank arm. I put a new crank arm on with the same pedal, and I coiuldn't get the pedal on the crank arm without crossing the threads. How do I stop this from happening?
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based on pic in the other thread the bike is lower end diamondback, with square taper bottom bracket. It is would be amazing if it was anything other than standard 9/16 size pedals.
OP needs to
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It's likely that the threads on the pedal spindle are filled with leftover aluminum from the first damaged crank and this is preventing the threads from properly engaging with the crank threads. Use a file or needlenose pliers or the like to get all that crap out of the threads before you try to thread it in again.
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...I like your username, but this is clearly user error. |
Originally Posted by squirtdad
(Post 22504056)
4. find a way to work with bike not upside down, can just hang from a pair of ropes. this will make all things easier
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Originally Posted by SurferRosa
(Post 22504027)
If you have an old Peugeot or Gitane with Lyotard pedals, it could be stamped "D" and "G."
So, to answer your question ... Yes. |
Originally Posted by SurferRosa
(Post 22504027)
If you have an old Peugeot or Gitane with Lyotard pedals, it could be stamped "D" and "G."
So, to answer your question ... Yes. |
His bike's a Diamondback. I'd bet 5 dollars he doesn't have Italian or French pedals.
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pedals had no markings for left and right, replacement pedals don't either, so I guess i'll just right-thread the one on the right very carefully, and if i don't feel resistance, then I guess i did it correctly
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Originally Posted by smd4
(Post 22505038)
His bike's a Diamondback. I'd bet 5 dollars he doesn't have Italian or French pedals.
Vilano Tuono 2.0 Aluminum Road Bike 21 Speed Disc Brakes, 700c Vilano Link doesn''t work, they don't sell it anymore |
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