Problems with BB

[ahconway]

After 4 trouble-free years, I've got a problem with my eccentric BB.

I heard some crunching in the bottom bracket and took it in to my local (Boston USA) shop. Seems that the bolts were no longer holding the eccentric shell in place, and one of them had dug a nice little ravine. The whole business was now loose. He turned the shell 180 degrees and that seemed to solve the issue, but about 175 miles later, the sound was back and I found that both bolts were now quite loose.

What does this mean? Do I need to replace the BB shell? Maybe there's a problem with the threads?

Anyone else experienced this?

Thanks

- Andrew C
www.velofellow.com

[stutho]

Hi Andrew,

When you say that the bike shop rotated the EBB 180 degrees do you do you mean that they rotated the EBB in the EBB shell?

If so then you need to get back to the bike shop quick.  Thorn / SJSC are very clear on this -
THE EBB MUST BE USED WITH THE THICKER PART TOWARDS THE BOTTOM.
See page 11 of the manual, running the wrong way up WILL damaging the BB

If alternately you mean that they switched the left to the right hand side and also switched over the cranks.  Then you may find you BB eventually starts to unscrew it's self from the EBB.

Sorry to be the harbinger of bad news!

Back to you original issue
The EBB is designed to be dented.  Some deformation in the EBB is to be expected and shouldn’t course any problems.  Someone on the list has replaced his EBB (I think after using it the wrong way up) but generally this is not required.

I’ve have not had a problem with loose EBB bolts however some on the list have.  Best solution would probable be to use a few drops of thread lock. 

Stuart


   

[vik]

Any tips on how to install and setup the EBB in a Thorn frame other than keeping the thicker side towards the bolts?  I'll be getting a Thorn frame with EBB soon and it will be my first bike with this feature.  How do I know how much/far to tighten the EBB bolts?