Different types of cranks

122 views  April 3, 2019

Cotterless interface

Cotterless

This is the standard crank that comes on most modern unicycles. The hub axle has tapered ends with a square cross-section and a bolt or nut to hold the cranks on. The cranks are forced onto the axle to create a friction fit and locked in place with the bolt or nut. You should never ride with loose cotterless cranks as this will round the corners off the axle and distort the square hole in the crank, preventing them from fitting tightly ever again.

 ISIS interface

ISIS cranks

These are a type of splined crank but have tapered axles so their removal is similar to cotterless cranks. You must use a crank extractor with an ISIS head otherwise it will damage the threads in the axle. Some extractors have a removable ISIS head so you can use them on cotterless and ISIS cranks.
 
Splined interface

Splined Cranks

Splined cranks are stronger than cotterless cranks and therefore are more suitable for muni or trials unicycling, but require slightly more maintenance. The bolts will probably need to be tightened after a week of riding and checked regularly after that. For more information read our section on maintenance of splined cranks.

Never ride with the cranks on the wrong side or you will destroy them.

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