Shimano Press fit BB86 SM-BB71 vs. SM-BB91

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Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby jeff_o » Sun Nov 25, 2012 12:06 am

ok so Shimano makes 2 levels of BB86 press fit bottom brackets: SM-BB71 and SM-BB91.

I was comparing these 2 specs from various website but could not find their difference. Most probably SM-BB91 is better because it's more expensive and higher in model number, but what could be the difference of the 2?

http://www.chainreactioncycles.com/Mode ... elID=44226

http://www.chainreactioncycles.com/Mode ... elID=61803
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by BNA » Sun Nov 25, 2012 6:41 am

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Re: Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby Nobody » Sun Nov 25, 2012 6:41 am

I don't know, but wading through this previous thread may enlighten you.
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Re: Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby Kenzo » Sun Nov 25, 2012 6:49 am

Yep, that's about the end of it.
My bike had a BB71 fitted and after 6000kms it was starting to groan a little. Now in essence the BB71 and BB91 are both the same as BB86(!). She'll width is 86.5mm.

I ended up replacing it with the road version from here:
http://www.enduroforkseals.com/id258.html
The road bike sees a lot more use at the moment so I want to make sure it gets pampered a bit more.

My MTB also uses a BB71 so in readiness for when it needs attention I just bought the BB71 sold by 'avantidude'.

What is most annoying is the BB's themselves can be bought cheaply, the tools to do the job however come to $100 or more.
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Re: Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby jeff_o » Sun Nov 25, 2012 9:07 am

@kenzo: so you're the one got it :p i was about to buy avantidude's BB71 but you got ahead of me. anyway have you got it already? can you check what's inside the box? i think aside from the left/right cups and plastic center tube, there should be a 2.5mm spacer? but i dont think we need the 2.5mm spacer for the 86.5mm shell width.
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Re: Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby Kenzo » Sun Nov 25, 2012 12:33 pm

Hehehe... Only organized it on Friday so I'll look in the box when I get it next week some time.
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Re: Shimano Press fit BB86 SM-BB71 vs. SM-BB91

Postby Kenzo » Wed Nov 28, 2012 10:24 am

jeff_o wrote:@kenzo: so you're the one got it :p i was about to buy avantidude's BB71 but you got ahead of me. anyway have you got it already? can you check what's inside the box? i think aside from the left/right cups and plastic center tube, there should be a 2.5mm spacer? but i dont think we need the 2.5mm spacer for the 86.5mm shell width.

No spacer included in the box - not needed for a road bike with an 86.5mm shell.

There is a BB71-41A and a BB71-41B.
41A is for 86.5mm shells
41B is for 89.5 or 92mm shells.
Probably the difference between them is the inner cover sleeve only.

Should be noted - the press fit BB I got from RWC did not come with any inner sleeve - I'm guessing they have more fiath in their bearings seal's ability to withstand ingress.
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