You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Is it just the length of the tube thing in the middle or are there other differences?
Just wondering as I can get an 83mm really cheap.
Cheers.
Pretty much. The liner tube may actually be the same for both and just push further into the cups on the narrower shell but not sure about that. Certainly a fat bike BB is just the same cups but with a 100mm tube. (assuming 24mm spindle here since there isn't room for the tube with 30mm spindles)
Generally it is just the length of the spacer tube in the middle, though I think certain BB's also had deeper cups (Mainly Saint BB's).
I think Sram GXP's are all the same except for the plastic spacer.
Saint BBs did have deeper threads
It's shimano road BBs you need to stay away from on a mtb.
1mm difference in cup width if I remember correctly. not sure which way round but would either end up with a bit of slop and inability to preload the bearings or insufficient spline engagement and knackered cranks after a few miles.
I guess it depends what you can adjust with spacers too.
Thanks all.
Cheers andyl, had been eying up a road bb but will avoid.
If it's a Hope then you can find PDFs on their site showing all the individual components - https://www.hopetech.com/products/drivetrain/bottom-bracket/bottom-bracket-threaded/#tech .
From their site: The unit is suitable for 68, 73, 83 and 100mm width bottom bracket
It’s shimano road BBs you need to stay away from on a mtb.
I've used road BB on mountain bikes plenty. Just re-use the slightly wider centre tube and spacers as necessary, I never noticed or measured any differences.
I'm also using a Shimsno road bb currently (about three months and with Raceface cranks). I just left the thinnest 0,7 mm spacer in to account for the difference in the cups and everything has been going great.