What are my options for replacing a Shimano Hollowtech II BB? I have had a 'Deore' equipped mountain bike for 3-4 months now. However, there is grinding noise from the area of the cranks and I suspect the bottom bracket.

On a local MTB forum I heard that Deore BB's last exactly that long. So I am worried about replacing the part with an exact duplicate (for fear of short service life).

Do more expensive Shimano groupsets use the exact same BB or is it different for each? Do they last longer? Is it normal for a Deore BB to fail after such a short time?
There are a number of options for replacing a Hollowtech II BB (whilst still retaining the Shimano cranks). The Deore bb is a cheap bb, higher Shimano levels should last better. Anecdotally I've heard premium Bb's last years while it's not unusual to use a Shimano BB a season.

The options are:


Shimano - Shimano has a number of different levels. BB51 deore level, BB70 SLX/XT and BB93 XTR
Other similar brands - Raceface X-type is compatible
Premium brands - Hope, Chris King and others
Hacks - replacing and upgrading the bearings while retaining the Shimano cups.


If you kill many bottom bearings it's good to understand why and address this. Water retention in the shell is a big issue if you ride in wet areas as is washing the grease out with a pressure washer. There are Bb's that have water drains built into the cups for drainage or you can drill a hole in your Bb shell if this is a real issue for you. Sealed bearings offer better water protection.

End of the day it's really a value choice, if you go through a lot of Bbs you should consider a premium one.