Main pivot bearing socket losing shape??

[GRG]

Good day hubbers

Noticed some looseness of the rear triangle, specially when standing on the pedals, sort of a side to side sway. Loose pivot screw was my first thought, upon closer inspection it seems to main pivot bearing socket has lost some of its shape or become oval. Or maybe the bearing has lost shape, not sure. 

Has anyone experienced this before??

Bearing spec is the correct size for the frame according to the blue print documents.

Thanks in advance, cheers

IMG_1332.mov

 

Edited April 2 by GRG

[RobertWhitehead]

It is something that sounds vaguely familiar, I can't recall if it was actually mostly on the BB and or if I've seen this on the pivots as well. Either way, it's a warranty replacement if still in place. 

[100Tours]

Has happened to me before after a long week riding in wet weather from Knysna to Stellenbosch. The bearing shell being carbon, and the gritty conditions creating a perfect grinding paste.

I don't think you can fix it

Edited April 3 by 100Tours

[dave303e]

At some stage that bearing siezed and then it wore out where the bearing seats. In machinery you would just weld and line bore that hole to size again. I wonder if there is a similar technique with carbon fiber resin

[BuffsVintageBikes]

Common problem on carbon frames, James Perry can fix it for you.

[HenkD]

1 hour ago, BuffsVintageBikes said:

Common problem on carbon frames, James Perry can fix it for you.

Do you perhaps have some contact details

[droo]

You don't say if you've replaced the bearing or not. Also, check the pivot axle for wear - it's often the culprit and easy enough to replace if the bike's not too old.

If it is the bearing journal, Loctite 638 retaining compound is your friend. 

[GRG]

Hi Droo, bearing replaced in December 2023, pretty new and running smooth.

The bearing journal refers to the 'hole' in the frame?

If Loctite is used, what do I need to consider for afterwards?

[droo]

The bearing journal is the seat, yes. If you used decent bearings they should still be fine, but I don't know your riding habits so anything's possible.

If you use bearing retainer you need to let it cure for 24 hours before riding, and removing just takes a bit more persuasion.

[BuffsVintageBikes]

2 hours ago, HenkD said:

Do you perhaps have some contact details

Details on their page... http://www.carbonbicyclerepairs.co.za/

[Mook]

4 hours ago, BuffsVintageBikes said:

Common problem on carbon frames, James Perry can fix it for you.

I've heard of this happening on carbon roadbike BB shells where the metal BB tube works itself loose from the carbon BB "housing". Also heard that guys pump epoxy into the cavity which apparently lasts.

This fix is obviously for a loose BB shell, not for an actual shell or pivot shaft that has worn down. What @droo said.

Let us know what the outcome is 🙏

[droo]

21 minutes ago, Mook said:

I've heard of this happening on carbon roadbike BB shells where the metal BB tube works itself loose from the carbon BB "housing". Also heard that guys pump epoxy into the cavity which apparently lasts.

This fix is obviously for a loose BB shell, not for an actual shell or pivot shaft that has worn down. What @droo said.

Let us know what the outcome is 🙏

If the threaded insert is loose take it to a professional.

If it's an ovalised shell, WheelsMFG make thread-together BBs that solve the problem permanently and for much less money.

[dave303e]

3 hours ago, droo said:

The bearing journal is the seat, yes. If you used decent bearings they should still be fine, but I don't know your riding habits so anything's possible.

If you use bearing retainer you need to let it cure for 24 hours before riding, and removing just takes a bigger hammer.

fixed....

[droo]

1 minute ago, dave303e said:

fixed....

But that's exactly what I said...