I’ve bought a spinning bike that has the cage pedals. I have cleat shoes which I prefer to ride in, so I bought some cleat pedals to fit to the spinning bike. Trouble is I've just taken the existing pedals off, and the thread is way bigger on the spinner pedal than the one I have on the pedals I have bought. Is there a bigger pedal or adapter available?

  • 1
    This is apparently a fairly common problem with exercise bikes. They tend to have odd-sized pedal threads. Impossible to give precise advice without seeing the threads. Mar 30, 2021 at 0:28
  • Worse (following on from @DanielRHicks) you can't usually replace the cranks, because they're non-standard as well. High-end exercise bikes use more standard bike parts, but cost a fortune
    – Chris H
    Mar 30, 2021 at 20:47
  • Please add photos of both sets of pedals.
    – Criggie
    Apr 20, 2021 at 0:13

1 Answer 1


Almost all adult bikes have 9/16" threads, with 20 TPI. One side is left-hand thread.

The other standard option is 1/2" thread which is intended for children's bikes.

There are rare vintage standards around 10 and 12mm but your spin bike wouldn't have these.

Finally there's a chance your spin bike has some proprietary pedal thread. Do you have access to calipers?

While pedal adapters do exist from 1/2" to 9/16" they are not cheap, and they separate your feet by some, also known as "increasing the Q factor"

  • Are you sure about 1/2” pedal threads and children’s bikes? Every children’s bike I’ve built had a square taper BB and 9/16” pedals. 1/2” is typically found on forged one-piece “Ashtabula” cranks
    – Pisco
    Apr 2, 2021 at 14:25
  • @Pisco depends on the size of the child the bike is intended for - small kids bikes is what I meant, like 12" wheels.
    – Criggie
    Apr 2, 2021 at 23:47
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    If there's enough material on the cranks, a friendly LBS may be able to re-thread them to a more common standard. But that would imply moving the exercise bike.
    – Carel
    Apr 20, 2021 at 7:06
  • @Carel good idea - taking just the cranks in might work. Do note that bicycle pedals are weird 20TPI whereas teh standard thread for a 9/16" bolt is only 18TPI. So it really does have to be a special tap for each side - can't rethread the pedals because they're already hardened and will be on-size.
    – Criggie
    Apr 20, 2021 at 8:24
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    @Criggie: Anyway a pair of special taps is required, because of lefty-righty.They are readily available but I'd say they're too expensive for just one go! Good luck!
    – Carel
    Apr 21, 2021 at 11:03

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