Rambetter

I have a tech question that nobody is able to answer it seems.

My 2008 Trek T2000 needs new bottom bracket bearings front and rear.
The crank and bottom brackets are made by SRAM/Truvativ, and the exact BB is GXP.

Here is the funny thing though. With a normal GXP bottom bracket, the right side has reverse threads and a large hole in the bearing. The left side has normal threads and a small hole in the bearing.

While this is true for the stoker BB bearings, it's the opposite for the captain on my T2000. That is, the right bearing cup still has reverse threads, but the right bearing cup has the smaller ball bearing hole. The left bearing cup has the larger diameter hole.

Besides flipping the eccentric and putting it in "backwards" I can see no way to find a solution, because I can't find a source for the "flipped" bearing cups. Any ideas?

Bezalel

My understanding of the GXP captain BB is that the cups are the same as standard cups, The bearings are switched (or the reducing shim is moved to the drive side), and both seals are "drive side" seals.

If my understanding is correct you should be able to assemble it from existing parts.

Rambetter

OK, that makes sense. How do I press out bearings and press them in the opposite way? It does not seem like that parts were designed with that in mind.

fietsbob

Working Blind, pictures?

Bezalel

This should help but you need to verify for yourself how yours are actually put together. If your cups are good I'd suggest the best aftermarket bearings you can get.

https://www.enduroforkseals.com/siteb...y_rwc_rev1.pdf

Rambetter

Thanks for the PDF document explaining how to install GXP bearings. I would have liked to have that a few days ago when I took the cranks out on the tandem.

Anyhow, as you can see from the pictures in the PDF you posted, there is a "outer shell" that is silver in color, and there is a bearing "pressed in" to the outer shell. The left and right outer shells are different and the left and right bearings that are pressed in are different as well.

You can now imagine that there are 4 permutations. 2 outer shell possibilities and 2 bearing possibilities makes a total of 4 different shell/bearing combinations. You can go to any store and buy the 2 permutations that are required for a single bike. However, on my tandem, for the captain, it requires that I have the 2 remaining permutations, which you CANNOT buy at a bike store.

I hope that makes sense. If I could somehow "press out" the bearing that is inside the shell, and then "press in" again, I could come up with the 2 combinations that I need for the tandem.

waynesulak

Have you tried contacting SRAM/Truvativ?

Rambetter

I have not. But I'm in the process of contacting Trek.
The cranks are stamped Bontrager even though they are made by Truvativ. I figure Trek should be the guys to handle this.

Rambetter

OK one of the guys at the Trek store did indeed end up calling a rep from SRAM or FSA or something, and there does indeed seem to be a bottom bracket with the cups switched. They are on the way. Hope it works. Ordered 2 pairs so that I don't have to go through this again if I ever need another one.

Bezalel

I see you found another solution but this is incorrect. The bearings, once knocked out are not meant to be reused. What should be done is knock out the old bearings and reuse the old cups with new aftermarket bearings.

Rambetter

Ah yes. I will keep that in mind as a last resort if I cannot source the correct parts.

Rambetter

Status report.
The LBS is taking more time than planned to get the "reverse" BB cups for the GXP.
In the meantime, I felt impatient and did some research online.
I went ahead and purchased this tool: https://www.enduroforkseals.com/id114.html
I have high hopes for the tool, especially considering the documentation goes into so much detail: https://www.enduroforkseals.com/siteb...p_by_rwc_f.pdf
In fact the pictures in the docs show the exact bottom bracket model that I have.

Also ordered some ceramic bearings for 60 bucks a set.

I plan to still buy the bottom brackets from the bike store if/when they arrive, I think 30 bucks a pop, assuming they are the correct model.

If anyone else stumbles upon this thread needing similar tools or parts, and needs help to either press out + press in bearings or order correct parts, don't hesitate to contact me directly, nlandys at gmail dot com.