My 2014 Stumpjumper has the original SRAM PF30 bottom bracket which is long overdue being replaced. I don't want to replace it with the SRAM part as I've had to maintain it constantly to get it this far. However, some of the alternatives have external bearings where as the existing bearings are within the BB and finish flush with the frame. On the drive-side there is a spacer between the cranks and the BB.
I'm confused what to replace it with and whether the spacer should be retained and how to ensure the chain line isn't messed up. Any help appreciated.
If you’ve used the bike since 2014 and still on the original Press Fit BB then I’d replace it with exactly the same! It’s probably some sort of record…
Its been knackered for a long time and I have continually had to top up the grease in the bearings to keep it going. I would have replaced it year's ago, but again, I don't know what to replace it with....
FSA and Gusset on the cheaper end of the scale, or Hope and Wheels MFG on the more expensive end.
The 2014 Stumpjumper has a BB width of 73mm
So you can use either inboard or outboard bearings, with the right amount of spacers
Outboard would be better, as you loose the need for spacers in the assembly
I won't try and recommend, as I know what I would use.. But nobody here would agree with me 😂
On the drive-side there is a spacer between the cranks and the BB.
That spacer is just drive side? I suspect if you then go with external bearing BB your chainline may be out as that would suggest an asymmetric BB shell.
If, as above the bottom bracket shell is 73mm wide. most non BB30 MTB cranksets are designed to work with an overall width of 92mm, hence the spacer. However if you fit an outboard bearing BB (of 92mm overall width), you lose the spacer, and the cranks will be 9.5mm inboard at the driveside, and 9.5mm outboard at the non driveside.
best bet is to go internal bearing type as fitted. PF30 or PF46 (referring to 46mm diameter of the BB shell.)
https://www.merlincycles.com/cervelo-bbright-press-fit-bottom-bracket-316346.html seems like a cheap alternative for the 30mm crankset you have. screws together rather than press in.