Mountain bikes have a hard life and the often multiple suspension bushes and bearings will wear out in the fullness of time. I’d been noticing a clunking, knocking sound when I pedalled hard on my Boardman FS Pro and after wiggling the rear wheel I found the culprit. Just one of the main rear suspension pivot bearings seemed to have some play. I needed to replace it. It would, of course, have been foolish to change only one side since the seemingly sound bearing wouldn’t be likely to last for long so I resolved to change both.
I’ve done this job before and the bearing in question is a rather common size, used on many bikes, at 25mm in diameter. I had 2 bearings in a spares drawer which I’d bought for an Orange 5 but never used. You may think that you need a specific bearing puller to remove such a bearing but since a puller is such a simple device you can easily improvise something which will work just as well. Pictured above is my homemade device composed of a large socket, nut, bolt and washer.
The internal diameter of the socket needs to be slightly larger than the diameter of the bearing so that the bearing can be pushed inside it. The washer needs to be a fraction smaller in diameter than the hole in the component so that it can push the bearing out of the opposite side. I removed the swinging arm (chain stays) of the bike by removing the chainset and then various fasteners. The bearing will only come out in one direction because one side of the component has a 25 mm hole to house the bearing and the other side has a smaller hole to stop the bearing from being pushed too far through. I kept a close eye on the homemade press to make sure it was always in line but the bearings came out easily. I used a vice (very slowly and carefully) to push the new bearings in dead straight. Don’t allow them to go in at an angle for fear of damaging the aluminium component, which is softer than the bearing itself. I then put a washer over each in turn which was slightly smaller than the bearing and again squeezed it in the vice to make sure the bearings were fully home.
I reassembled the back of the bike using Loctite to make sure the threaded parts would stay together in the long term. It’s also important to make sure that components are clean and corrosion free before assembling and adding grease in places may stop things from seizing together later. The bike is now ready to rip again, quietly, hopefully.