Changing rear hub bearings 2009 road Fulcrum hub.

[Gearoidmuar]

This was a nightmare for me. I've extensive experience of old hubs and even used to dismantle old freehub bodies, but this was unexplored territory and I was misled by an incorrect diagram on-line. I eventually worked out what was what. It took me ages. It would take you no time at all if you had a good explanation, so here goes. Problem was wobbly wheel on its axle. Too much play. Obvious bearing gone.

Very simply, the hub is constucted as follows.

From the Drive side. Quick release and skewer, Axle with fused nut. Narrow washer, freehub bearing, of slightly smaller diameter than axle bearings, freehub which sits in a toothed bay with external pawls. This assembly is covered by a narrow seal on the freehub body. This is the crucial bit. Behind this is a wider washer which keeps back of the freehub, just, from meeting the underlying main bearing which is slugly fitted in the hub body. On the other side of this is a long tubular washer and then on the other side the second bearing, a thin silver cap which fits over that with an inner protuberant bit facing outwards, then another thickish washer and then the nut which screws into the axle. That's it. The key thing which was wrong was that the second fattish washer which from the diagram appeared to be inside the second thinnest one, outside the left bearing, in fact keeps the freehub body clear of the main bearing, just on the other side. This may mean nothing to you now, but when you have the thing in pieces and are scratching your head, it should all become clear.
The difficulty arises in that you have to hammer it apart and next thing, it happens so fast you can't note what's happened.

It worked. Wheel perfect. It took me two hours of messing.
Hint. Easy way to get bearing out is to use an old narrower axle from the other side and a couple of tap with a hammer.

P.s. I was very very impressed with the design of this hub. It's a huge improvement to my mind of the old Shimano ones.

[Brucey]

Not unlike Hope, some campag, Novatec and others, it is light and relatively simple but...

- water gets into the pawls space pretty easily
- the bearings are not ideally suited to high lateral loads
- the bearings are not usually adjustable for preload/wear
- there is slightly higher bearing drag because there are at least four bearings and between four and eight seals all told.
- All four bearings are loaded and turning when you are pedalling
- the axle sees higher loads than in a shimano freehub

CF in a classical shimano freehub the freehub bearings are static when pedalling and will (if adjusted to zero free play) pretty much last forever. The only source of drag when pedalling is the main bearings and their (two) seals. The bearings are stronger than the cartridges fitted in the Fulcrum etc hubs.

So for unladen work the Fulcrum pattern is a good hub design but for laden touring etc the classical shimano design is still better IMHO.

cheers

[Gearoidmuar]

In this Fulcrum hub, Brucey, there are only two bearings (plus the smaller bearing in the freehub). As for water getting into the pawls, I'm riding this bike for 6 years and this is the first time they've seen the light, or in the case of Ireland, the dark of day, and they looked fine! What I liked about the design was that you didn't need a large allen key to get the freehub off, and despite their nakedness, you can get at the pawls without an appawling (sorry about that) amount of trickery or a special tool!

[Brucey]

you've done well to avoid water getting in... but if not that, what caused the bearings to fail, I wonder?

BTW in this design there are invariably two bearings inside the freewheel body, that allow it to run on the axle independently of the hub body; they can clap out too, which means a new freewheel body (Fulcrum's solution) or more fun and games pushing bearings out.

cheers

[Gearoidmuar]

Weight??

Don't know. I took out the bearing in the freehub and didn't see another one. The back of the freehub has a recess into which a washer which fits around the axle sits and this presses against the inner ring of the main bearing.

[Valbrona]

Usually the outer bearing goes before the inner one.