Bearings on unicycles generally last a long time; even when you take your unicycle in a fountain, or the sea, or just splashing around in the mud. They do give up in the end though; normally at the worst moment possible. You hear them grinding first, then when you turn the wheel slowly by hand you can feel the restriction in the movement.
This document is to give you a guide of what to do if you are brave enough to try and replace them yourself. With the appropriate tools this not a complicated or hard job but Be warned without the proper tools this is not an easy task some bike shops will be able to do this for you.
What you will require:
- Replacement bearings - see our catalogue for quality replacement bearings.
- Crank extractor - again we sell these.
- Socket set - not really necessary, normal spanners can do but makes it easier.
- 14mm socket or 8mm Allen Key, to remove the crank bolts
- Rubber hammer/mallet - again not really necessary.
- Bearing puller - we sell these, they are essential.
- Pipe - size to fit over spindle and touch inner bearing race
- Scrap Wooden Block - not really necessary but it helps to prevent damage.
To remove and fit bearings:
- Remove the dust covers from the cranks.
- Remove the nuts/bolts from the centre of the cranks
- Remove the cranks using a crank extractor (see instructions). Be sure to screw the extractor fully home before you start to extract the cranks.
- Remove the wheel from the frame, in most cases this involves removing
4 bolts from the bracket that surrounds the bearing. In the case of the Pashley the screws are in the side of the fork legs and the bearing holder stays with the bearing.
- Fit bearing puller over bearings and use a spanner to tighten the bearing puller to pull the bearing from the hub. Be sure to seat the legs of the bearing puller securely under the bearing so that it is not destroyed before it is removed from the hub. On a Pashley you need to extract the whole bearing holder. Do not try to remove with a lever or screw driver behind the bearing, it will damage the hub. For ISIS hubs use the ISIS cap from the crank extractor or something similar to prevent the bearing puller damaging the threads in the hub. (With Pashley and Dodger bearings they will require pressing out from the bearing holder and then the new ones pressed back in before refitting to hub. It is recommended that this is done by a machine shop).
- Once bearing have been removed clean the hub shaft with wire wool and a little oil to remove any rust or dirt.
- Fit new bearings over the shaft (be sure to fit spacer on first if one was fitted) and gently push, ensuring that it is square with the shaft. When it can not be pushed any further by hand slip a pipe or socket on top. Ensure that the pipe/socket is pressing on the centre of the bearing, not the outer ring or rubber seal. Place the wheel on a piece of scrap wood to protect the other side of the hub shaft. Hit the pipe/socket with a hammer until the bearing is seated home.
- Clean the bearing holders to be sure that there is no dirt or rust.
- Re-fit the wheel in the frame. Be sure not to over tighten the bearing cups as this will impede the performance of the bearing.
- Re-fit the cranks on the hub. Be sure to check that the cranks/pedals are on the correct side. On the end of the pedals there is a letter L or R for left and right and a letter on the back of the cranks.
- Tighten the nuts/bolts in the end of the hubs, these must be secure. Tighten well but do not over tighten.
- Replace the plastic dust caps if removed earlier.