Shimano Bottom Bracket numbers- Will this work???

BB on my 09 Stumpy FSR is feeling a bit “gritty” so I think it is geting close to time to replace it. According to the Spesh specifications, the BB (which is still the original) is a BB50 Hollowtech 2 type. Naturally these seem no longer to be available. So I was going to replace it with a BB51. BB shell is 73mm but I am concerned that the original cranks & chainwheel (which I don’t need to replace yet) might not fit (as implied by the technical docs from shimano for the BB50/51/70 as the “applicable chainwheel” reference numbers are different)…

Anyone know if the BB51 will be OK? Will I need any new or different spacers?

Ta
k

It will be fine. Those reference numbers are just to the equivalent ‘range’ of crankset, ie. Deore, lx, six, xt, Xtr

As its a 73 shell, just use one spacer on the drive side, unless you’re using a bb mount chain device, in which case no spacers at all.

Where are you getting it from?

Top spec XTR BB90 are only £17 here
http://www.rosebikes.co.uk/article/shimano-xtr-bottom-bracket-cups-hollowtech-ii-sm-bb90/aid:274227

All “MTB” ones will be fine, road (tiagra etc) use a different size axle.

What makes an XTR an xtr?
I have only used Deores. What is different? Sealing? Bearings?

I have a second hand Hope to try next. This has larger & sealed cartridge bearings, compared to Deore, with another dust seal that is tight on the crankshaft, loaded against the bearing inner and its outer dia runs in a groove in the cup.

XTR any better?

‘was’ is mostly correct.

Rosebikes do charge delivery, so stock up and get 3!

The road models are based on a 68mm shell with a shorter axle on the cranks.
The MTB models are based on a 73mm shell with a commensurate axle.
You add a spacer each side for use in a 68mm shell.

Saint is based on an 83mm shell….so do not go there!

The new Zee may also be for a larger shell…not seen all the specs yet.

PaulD

was- cheers, that’s cheap. They are £45 on Wiggle!!!! I kinda guessed they were the various Deore, XT, XTR ranges but was concerned that the cranks might be different- to force me to upgrade the whole lot…

Thanks for the help guys.Looks like Rose bikes will be getting a visit from me 🙂

Ordered! Cheers!

What makes an XTR an xtr?

No idea. If you close your eyes can you tell the difference between a deore and an XTR rear mech?

I would hope they use better bearings and better seals for the same or less weight, but I have never had both to compare.