BB91 Shell & BB30 Crankset

Discuss light weight issues concerning mountain bikes & parts.

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loucastillo
Posts: 4
Joined: Thu Aug 14, 2014 2:28 am

by loucastillo

Hi all - first time.
I have situation and I'm wondering if anyone can help.
I have a Giant XTC Carbon frame with a press fit BB91 shell and I want to use my SRAM X0 BB30 crankset and I have found a bottom bracket set from Wheels Manufacturing at $250 + freight.
Also, I have found that the inside diameter of BB91 is 41mm and the BB30 spindle is 30mm and.........headset bearings are this exact measurements; can I use headset sealed bearings as bottom bracket bearings?
I don't know the inner working specs of headset bearings.
Cheers...

by Weenie


jooo
Posts: 1508
Joined: Wed Feb 02, 2011 3:48 am

by jooo

As long as your spindle is long enough (you may still need to modify the preload mechanism), you need bearings like these:

Image

Rotor/THM and a few others make them.

loucastillo
Posts: 4
Joined: Thu Aug 14, 2014 2:28 am

by loucastillo

Thanks Jooo, can you give me more information about this type of bearing. I can see in the image the outer edge to stop the bearings from walking towards the centre of the shell. So far the BB91 shell has enough room to safely accommodate the length of the BB30 spindle. My biggest unknown is how much the headset bearings that I am using as bottom bracket bearing will last or will cause damage to the shell and or spindle. I'll start looking for these bearings...
Found - www.enduroforkseals.com
Cheers,
Lou

slim83
Posts: 69
Joined: Wed Jan 28, 2009 4:27 pm
Location: Missouri

by slim83

i have used this BB on a scott spark frame with a hollowgram crankset(bb30) the biggest concern you will have is clearance of the crankarms with the frame and whether or not the bearings line up with the machined spots on the crank spindle.

http://www.raceface.com/components/bott ... inch-bb92/

loucastillo
Posts: 4
Joined: Thu Aug 14, 2014 2:28 am

by loucastillo

Thanks. That was one of my concerns but I'm confident the spindle bearing seats and bearings are riding where they should be. There is plenty of clearance, 2mm per side and I have put a lot of stress on the crank arms by climbing a few hills and so far (touch wood) no unwanted wear marks to be seen. Thanks for all your help, I have stopped riding the bike until I can find a bearing that is actually made for BB's. Cheers, Lou

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ultimobici
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Joined: Sun Nov 21, 2004 2:45 pm
Location: London, UK
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by ultimobici

Try Rotor


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by Weenie


loucastillo
Posts: 4
Joined: Thu Aug 14, 2014 2:28 am

by loucastillo

Hi ultimobici, I found the BB I need and that is, Race Face BB92 "Cinch". I'll install this weekend and go for a spin. Thanks to all who helped me and suggestions. :)

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