Hi,
Just took out a race face external bb to swap to another frame and found this bit on the right hand side.
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It's plastic and was on the non drive side fitted so that it seem to cover the polished bearing surface.
Obviously its worn out - but surely the bb can't rely on having a plastic bit between the surface of the axle and bearing?
I tried fitting without it and there is play on the non drive side so I guess its needed.
Bit confused though I guess I need a new bb!
Any ideas?
Thanks
It's a top hat to cover the bearings. One either side.
Not shown in the exploded diagram but part of the cups that screw into the frame.
Tim
Yep widely known to be a bit crap - the shimano plastic "top hat", Hope BBs CK BBs and enduro's replacement bearings all have 24mm ID and hence no plastic spacing required...
Hmm. What bb should I get to replace it? Don't like the idea of that.
Don't want to spend a fortune, <£40?
You need one of these [url= http://www.chainreactioncycles.com/Models.aspx?ModelID=39505 ]Top Hat [/url]
Edit: The idea is that when your bearings seize the inner part of the bearing doesn't destroy your axle, just wears out the plastic spacer which is what seems to have happened with your bb
surely the bb can't rely on having a plastic bit between the surface of the axle and bearing?
Yes it can and does obviously, I'd prefer the plastic top hat to wear rather than my axle, hense why I won't touch Enduro replacement bearings.
Wat BB, for less than £40 - Shimano SLX.
It's a nylon 66 bush, 6805 bearing have an inner or bore race diameter of 25mm. The thorugh axle on a standard crank is 24mm. The bush is there to reduce the bearing inner race to fit the crank without leaving any play.
On the race face bb's etc it is very hard to remove those bushes without damaging them. I have a prototype bearing puller that strips most frames bearings and bushes also headsets and bb's, which makes it easier but it's still a bit tricky.
Not sure if you can get replacement ones of those bushes, if you live near edinburgh and can get an old raceface BB or similar bb that runs a 6805 I can recondition it with performance bearings that will last years fairly cheaply.
Hope run INA bearings in their BB's which is why they last as long as they do, if the used a decent grease and filled them to the brim they would last a good bit longer.
It's called a bearing cap and is available for a matter of pence from all good bike shops. You DO NOT need to replace your bb due to this.