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  1. #1
    Air
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    Destroyer of Wheels Air's Avatar
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    New pedals won't fit older bike - what can be done?

    So I bought folding pedals for my vintage russian folding bike. Took off the old pedal, tried to screw in the new one and it wouldn't thread in nicely by hand, seems to be ever so slightly annoyingly larger then the hole. By sight they seem to be the same thickness and thread - though I'm not an expert. I bought another pair for my regular mtb and they fit fine. Aren't pedals universal? I think I have a few options if I want to keep the folding pedals (which I do):

    a) Murphy's Law - if it's stuck force it. If it breaks it needed replacement anyway.
    Problem here is that the crank is older, not sure I really want to start the possible slippery slope of replacing one part to get another to start. If they thread in then problem solved, if not then I could just go to option b....

    b) New Crank shaft
    How much do these cost? It seems that this crank shaft screws onto where it goes into the bottom bracket (if this isn't clear I can post some pics) so replacing it shouldn't be a problem PROVIDING I can find a replacement. Again, I'm hesitant to take a step down that slippery slope and wind up replacing the bb too - I've spent a little too much money already and would like to temporarily stop the bleeding and enjoy it for a few months

    c) Have a machinist drill out and/or retap/rethread the hole in the crank shaft
    As long as the the pedal can be threaded into the crank shaft it should be strong enough, right? One lbs isn't equiped to retap the hole - anyone know a good and cheap machinist in the NYC area?

    Let me know what you think, thanks! (Also if this should go to vintage section I apologize - figured it was more mechanical then vintage in topic).

  2. #2
    Amateur Hack
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    if I remember correctly,
    old pedals = 1/2"
    new pedals = 9/16"
    sorry you are out of luck. don't force it. it won't fit. they really are different sizes.
    drilling and tapping should work, but I can't speak to the strength of the crank afterwards. Of course it depends on how much metal you have left.
    good luck!

  3. #3
    sch
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    You need to determine what the thread is for the original pedals and compare this with the new pedals.
    You will need a thread gage and reasonably precise 0D on the pedal threads (accuracy at least 0.02" )
    to see what the incompatibility is. A difference in the thread pitch or unlikely, TPI would mean the use of force would strip the thread, crank and possibly pedal as well. The standard pedal thread is 9/16x20
    R and L handed, which will drive a machinist crazy as the taps are unique to bicycles and have no other use. The Russians have their own idea of what is standard, and apart from the chain, it would not be surprising that everything else is 'non standard' from a bicycle POV. If the TPI/pitch is indeed identical
    and the OD very close a heavy power wire brushing of the pedal threads may take off enough metal to allow the pedal to be screwed in.
    Steve

  4. #4
    Senior Member ken cummings's Avatar
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    Old bike metric, new pedals english? Are there any Russian bike clubs that could give you a lead on original pedals? I knew a man who rebuilt a 62 Dodge Challenger to factory original condition and parted out two other Challengers to do it, at $23,000. Some Russian might be able to sell you a mangled old frame with two good pedals.
    This space open

  5. #5
    Cycle Dallas MMACH 5's Avatar
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    You can still find 1/2" pedals at your LBS. If they don't have any or won't order them for you, they can be found at the dreaded wally-world.
    That's gonna leave a mark.

  6. #6
    Air
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    Thanks all! The original pedals are fine - just wanted to get foldable ones so I don't keep kicking my bike when I walk through the door. My shins will thank me

    I should try to figure out what bike this is - I've done some google searching and came up with absolutely nothing. That amazed me!

    I took a closer look at the threads and screw for the pedals. Holding the old and new up to the light there's no difference in the thread distance. I'll bring both to my lbs and see if they can determine the thread gage or test run a 1/2" pedal to see if it fits in there.

  7. #7
    biked well well biked's Avatar
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    Quote Originally Posted by Air
    Thanks all! The original pedals are fine - just wanted to get foldable ones so I don't keep kicking my bike when I walk through the door. My shins will thank me

    I should try to figure out what bike this is - I've done some google searching and came up with absolutely nothing. That amazed me!

    I took a closer look at the threads and screw for the pedals. Holding the old and new up to the light there's no difference in the thread distance. I'll bring both to my lbs and see if they can determine the thread gage or test run a 1/2" pedal to see if it fits in there.
    I'd post your questions about the bike's origins on the classic and vintage forum, there have been discussions of Russian made bikes there before.

  8. #8
    Air
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    Will do, thanks!

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