Hey all,
I have a 2019 Devinci Wilson that is stock with a GXP-BSA BB. I decided to swap out my crankset and ordered a Hope BB to replace the stock one. When I tried fitting the new BB, the threads engage for about a turn and then tighten up. I verified threads are clean and that I am not cross threading but could not install the BB. I measured the Hope BB threads compared to the old GSP and the OD of the Hope measured 0.1mm more than the GXP.
Went to my lbs to see what they can do, possibly to chase the threads. They couldn't get the chasing tool to bite clean and were as confused as I was at this point. I had a Shimano BB and a Sram DUB BB lying around and tried to fit them. The DUB BB went on without issue, the Shimano ran into the same issue as the Hope.
Anyone else ever come across this? Does SRAM just hit a lower tolerance on their BSA BB's and Devinci machined to fit a SRAM based spec? I'm at a loss a to how this could happen considering BSA is pretty straightforward.
I haven’t heard of anything like this, but it could just be a tolerance issue. I’d reach out to Devinci and see if it’s something they’ve seen before or have advice on.
I doubt this will help, but my first thought would be to try looking at/measuring all the BB’s side-by-side just to confirm the thread spacing lines up. If you do that, you could also try to measure the frame’s thread spacing.
Do you know if, when chasing the threads, they tried different chaser sizes?
Sent the email out to Devinci, I'll see if they have any insight. I'll take a look at the thread spacing as well, I think I just assumed the diameter difference was the issue but that's a good idea to check the threads.
The bike shop only had one size for BSA (Parktool BTS), are there over/undersized taps available?
I don’t believe there’s any for being manufactured for 0.1mm off of typical BSA sizes. There may be something out there, but it’d probably be a real pain to hunt down.
Another idea would be to clean the frame and the SRAM BB really well, then just screw it in and out a few times. Pay close attention to anywhere you may feel it possibly starting to catch, then see if there’s anything off around that area in the frames internal threads. Could be that there was a burr or small dent that the SRAM somehow adapted to over time.
Devinci customer support has not seen this issue before but might get some headwind with a replacement for the BB Shell (The Wilson has an aluminum insert BB Shell the main pivot rotates around).
I also borrowed a thread gauge and both the Hope and DUB measure at 24 TPI. Need to pull the Wilson back down (I put it all back together for a ride) to check the GXP and the shell but seems likely the thread pitch isn't the issue. I'll take that chance to check for burrs like you suggested.
As an update, thread pitch all matched but the shell's seemed a bit rounded. Devinci mentioned they spec GXP and Raceface BB's and have not had an issue.
I ended up lightly filing the outer threads on the Hope BB, put lots of grease on, and wrenched it on. Force to install seemed consistent (Increased as more threads were in but it was expected). Removal is a problem for future me but I do feel confident I'll be able to manage.
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