Frequently Asked Questions (FAQ)

Search our articles or browse by category below

How to change unicycle cranks

There are four main types of cranks commonly found on unicycles: cotterless, ISIS, splined, and cotter-pinned. Additionally, there is a newer type called Q-Axle. Follow the instructions specific to your crank type below.

Cotterless Cranks

Cotterless cranks are the standard type found on most modern unicycles. The hub axle has tapered ends with a square cross-section, secured by a bolt or nut. The cranks are pressed onto the axle, creating a friction fit, and then locked in place with the bolt or nut.

Important: Never ride with loose cotterless cranks, as this can round the axle corners and distort the crank hole, making them impossible to fit tightly again.

To remove cotterless cranks:

  1. If there is a dust cover, remove it.
  2. Use a 14mm socket spanner or an 8mm Allen key to unscrew and remove the nut or bolt (turn counterclockwise).
  3. Fully retract the central shaft of the crank extractor before screwing the outer section clockwise into the crank.
  4. Turn the shaft to extract the crank.
  5. Unscrew the outer threaded section to separate it from the crank.

To fit cotterless cranks:

  1. Gently seat the crank on the axle stub.
  2. Lock it tightly in place with the bolt or nut.
  3. Ensure the right-hand crank is on the right side and the left-hand crank is on the left side before riding to avoid damaging the cranks.

ISIS Cranks

ISIS cranks are the standard for the strongest hub-crank interface and are used on various unicycle types, from Freestyle to Trials and Road. They are a type of splined crank with tapered axles, making their removal similar to cotterless cranks.

Note: Use a crank extractor with an ISIS head to avoid damaging the axle threads. Some extractors have a removable ISIS head, allowing them to be used for both cotterless and ISIS cranks.

Splined Cranks

Splined cranks are less common now, with Qu-Ax being the primary company using this technology as of 2019. They are stronger than cotterless cranks and are suited for muni or trials unicycling but require more maintenance.

Types of Splined Cranks:

    • Onza
    • Kris Holm
    • Profile
  • Qu-Ax
  • Koxx
  • Onza/Kris Holm
  • Qu-Ax ISIS
  • Onza ISIS
  • Nimbus ISIS
  • Kris Holm ISIS

Compatibility: With the exception of Onza with Kris Holm/Onza cranks and all ISIS cranks (excluding Koxx), these cranks are not cross-compatible due to different spline formations.

Maintenance Tip: Bolts may need to be tightened after a week of riding and should be checked regularly thereafter. Never ride with the cranks on the wrong side, as it will destroy them.

Q-Axle Cranks

Qu-Ax and Kris Holm now use a modern spline system that is not interchangeable with older splined systems or ISIS. These cranks are designed to prevent incorrect installation direction, but they can still be installed on the wrong side.

To install Q-Axle cranks:

  1. Ensure the right-hand crank is on the right side and the left-hand crank is on the left side. Riding with them on the wrong side will cause the pedals to unwind.
  2. These cranks require a spacer behind them. The colour of the spacer indicates its size:
    • Black = 5.8mm
    • Silver = 4.8mm

Cotter-Pinned Cranks

Cotter-pinned cranks are no longer used on new unicycles. The crank is held in place by a tapered bolt called a cotter-pin, which is at a right angle to both the axle and the crank.

To remove a cotter-pin:

  1. Slightly unscrew the nut.
  2. Carefully hit the nut with a hammer or mallet.
  3. Repeat this process until the pin is completely removed.
  4. Tip: Do not fully remove the nut before hitting it with a hammer, as this can bend the pin, making removal more difficult.

When changing a cotter-pinned crank, it’s recommended to replace the cotter-pin as well. Before riding, ensure the right-hand crank is on the right side and the left-hand crank is on the left side to avoid damaging the cranks.

Categorised in:

This post was written by UDC