on a Rocky Mountain front 20mm carbon hub, as it's rocking side to side, backward and forward.

Headset seems fine as I made sure I preloaded correctly the headset, whilst clamped to a bike stand mind.

I thought you could only preload bearings on say Chris King or the like.?

Help much appreciated.

no preload needed or possible. If it's wobbling they must be worn out or axle not done up.

What fork?

Headset is best set up with the bike on the floor. Lock front brake, or turn wheel perpendicular, and rock back and forth.

Axle on the forks/wheel should be tight enough as I assembled properly, the bike on Friday, long light'ish ride Saturday.

I screwed the axle in first of all to finger tight then a wee more.
Then secondly tightened pinch bolts up carefully to finger tight and no more so all ''should'' be good.

Maybe the hub bearings have had it and that it will need replacing, – can they be replaced would you know?

thankyou

@Three_Fish – It's a fox 36 (2006), and yes I know as I usually do the exact same method regarding headset setup.

For all I know it's on it's original bearings as it has had 2 seasons use as a demo bike.

I'm guessing that I have answered my own question then no?

What I really need to know is if there's a way of preloading the bearings on this particular hub.

What I really need to know is if there's a way of preloading the bearings on this particular hub.

I already said you can't, and cartridge bearings don't like preload unless tapered, surely ? In any case, preload doesn't fix wear…

Sure thing, ok then so basically I can replace the bearings then?

Never done this operation before so might need to call in the A-Team.

so basically I can replace the bearings then?

yes. Find out what type of hub is is and someone will know how. Typically you displace the spacer between the bearings and knock them out with a drift (AKA screwdriver)

The bearings will usally be one of 2 sizes. 6804 run direct on the axle, and 6805 run on a 24mm sleeve that the 20mm axle runs inside.
It is possible to preload hub bearings with a 24mm sleeve. Mavic hubs run on this principle, as do Chris Bling, but it's so you can reduce side loading to let the hubs roll smoother. Not to take out side play from wear.

Ok then, thanks Si/skyline. 😀

but it's so you can reduce side loading to let the hubs roll smoother.

please could you explain how preloading reduces side loads ? Also, what side loads are there on a bicycle wheel bearing ?