Ugh, I put my tire on backwards and trashed the crank threads

Unicycles and Equipment
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I have an old Miyata with a 24” wheel. I just swapped the tire and somehow got things turned around. As a result, I’ve stripped both cranks. Looking for a solution since I can’t seem to find the right replacement parts. 5.5 inch crank. Insights welcome.

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So did your pedals come loose while riding and wreck the crank’s threads as they did? What type of cranks do you have? (Cottered, cotterless/squaretaper, etc.) If you have cotterless/squaretaper cranks then replacement should be easy. 5.5” is equal to 139.7mm, so the closest length you could buy is probably 140mm like these:
https://www.unicycle.com/united-black-cotterless-cranks-140mm/
You could go with a different length or material depending on how original you want it to look.
Finding replacement cottered cranks will be harder, since they are outdated and no longer in production (that I know of). For cottered cranks your options are probably going to be:

  • Search Ebay or other sites
  • Search bike shops dealing in used parts
  • Part out another old unicycle with cottered cranks
  • Get a set machined
  • Switch to a cotterless hub
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I did the same thing to my 24" a couple months ago. After seven years of riding, you’d think I’d be immune to that foul-up. Duh! Luckily for me, I routinely tighten the crap out of my pedals, so nothing got loose.

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The tools are expensive but you could fit inserts if there is enough metal.
You will need a left and a right.
https://www.cyclestation.com.au/10-x-unior-left-hand-thread-inserts-for-9-16-pedal?gclid=EAIaIQobChMImq7r8tvz8AIVxSFgCh2izgPbEAQYASABEgLytvD_BwE

3 Likes
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Thanks UniBeetle! Do you mean that I can just buy a replacement crank off the shelf? I don’t necessarily need to buy the actual Miyata crank? It’s old but cotterless.

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Thanks! Good idea. I chatted this over with the bike store guys…and it might work…if there’s enough metal in the crank itself.

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Noted! Hot tip on always tightening my cranks.

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Cotterless cranks should all be the same size and interchangeable. So yes, you should just be able to buy an off the shelf set. You will need to get an appropriate crank puller or take the uni to a bike shop and have them remove the cranks; which might be cheaper if you don’t plan on changing the cranks out again. There is a cool set of 125/150mm two hole cotterless cranks by Standard High Wheel that might interest you. They are discussed in this topic: Dual hole 125/150 square taper (cotterless) cranks

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Good point. There’s no reason you need to replace them with identical cranks. Now is a good time to go either shorter or longer if that’s what you want. They’re $20, order something fun.

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These only really work with Aluminium cranks and from what I understand the old cranks on Miyata were steel.

If it is the aluminium ones, then this is an option.

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Which option do you mean?

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He is referring to: