Bottom bracket - bearing replacement

evans868

Hi - I have a Boardman MTB Pro 29 (2016) which comes equipped with a SRAM GX 1000 chainset. It has developed a creaking noise but only when I pedal. I do think its a bearing (although reading other threads I will take a closer look to see if so) what I can't figure out is what tools / bearing etc do I need to replace if required?
Thanks all

karljeff72

Have you checked the pedals just in case.
If it is the BB than you need GXP BB and you can use the same tool for Hollowtech.

gomezz

It could also be creaking from the seat rails.

whyamihere

It's probably a BSA threaded GXP bottom bracket, if so you can't really just replace the bearings, you replace the whole unit. BSA refers to the threads which are in the frame (also sometimes called English threaded). GXP is Sram's older BB type (they've since gone to a new type called DUB). They look like this: https://www.halfords.com/cycling/bike-parts/gears-drivetrain-and-cables/truvativ-bottom-bracket-gxp-team-cups-english-907642.html - You'll be able to see the external cups if you look at where the cranks go through the frame. To remove it and fit the new one, you'll need something like this: https://www.halfords.com/cycling/bike-maintenance/bike-tools/bikehut-external-bottom-bracket-tool-164172.html

If you can't see the cups, it might be a press-fit, if you post a picture it might be obvious which standard.

evans868

Thanks for your responses so far... here is a photo I already took (Im guessing this may not be what you need to see but let me know...)

whyamihere

That means it's not GXP, as the bolt for GXP cranks is on the non-driveside. A bit of Googling suggests it might be BB30, which is one of the many press-fit standards, but that could either be true BB30 or PF30. Fitting and removing becomes more complex, as the old BB needs to be knocked out and the new one pressed in.

There's a guide with measurements for which standard it is here, measuring the shell is the best way to know for sure: https://www.bikeradar.com/advice/buyers-guides/the-complete-guide-to-bottom-bracket-standards/

If you're not confident with this, it may be better to take it to a decent bike shop, both to make sure the right BB is fitted and for them to use the specialist tools.

evans868

@whyamihere thanks so much for your advice, its much appreciated. With extra cost of tools and potential for error I agree with what you have said; appreciate you taking the time to help me out. Thanks to everyone else too for helping.