I’m refurbishing my old DH bike as a winter project. One thing that’s always niggled me with this bike is that when I press a brand new seatstay bearing into the frame, it’s basically locked solid. I may well have been riding it for years with the pivot axles spinning inside the inner races, rather than the bearings moving, although there doesn’t appear to be wear on the axle.

Anyway, has anyone experienced this? My guess is poor tolerances on the frame bore at manufacture; slightly too small leading to a binding bearing. I happen to have been gifted a Dremel at Xmas, so thinking that removing a sliver of material may free it up? 😀 Thoughts anyone?

Right idea, but I think a Dremel would be too much. The difference you need to make is almost imperceivable.

Onzadog-proposal:

Dremel would be too much

I would fear the Dremel as well.

@greigb: and yes – what you describe indicates that “some” tolerances are off. But which? Where to modify…? And if you like to modify possible to use fine sandpaper inst :?ead of a Dremel?
If you ruin the frame and end up with “play” – you risk cracks and the end of the frame.

I may well have been riding it for years with the pivot axles spinning inside the inner races, rather than the bearings moving, although there doesn’t appear to be wear on the axle.

For me: this is a hint that you might be lucky that “under load” the friction between axle and inner race increases and the axle stops spinning? In the “load cases” the bearing starts working?
Very hard to check this.

One thing that’s always niggled me

would niggle me as well.
😥

I take your point re: Dremel, I’m probably just looking for something to use a new toy on. 😉 That said, I do have some sandpaper type attachments, they’re not all ceramic type grinders.

I’ve got some digital calipers, so I might take a few measurements round the bore, see if something has been obviously ovalised or if it’s all about even. Can compare it the outer race of the bearing too. Appreciate it’s fractions of a mm that could make the difference though.

it’s fractions of a mm that could make the difference though.

Yes.

Good idea.

Good luck!
🙄

The bearing seat must be ovalised, not too small. To compress the outer race sufficiently to cause it to bind would require a huge radial force, which I doubt you could get by pressing it in – and if you did, the corresponding tension would crack the seat.

Thanks Greybeard, if it is ovalised I’m pretty sure it’s been like that from new, on both sides. Maybe something happened at heat treatment (although not sure of the order of things).