bottom bracket confusion

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kamil1891
Posts: 604
Joined: Thu Mar 24, 2011 16:59 pm

bottom bracket confusion

Postby kamil1891 » Sun Dec 16, 2012 23:05 pm

Basically, I don't know much about bottom brackets that's why I seek some help on that topic.

I've currently got a BMC pro machine, with old sram red groupset. The bottom bracket is GXP and the thread is English, I believe.
I would like to buy a different bike with the 2013 sram red gruppo and swap over the groupsets but I'm not sure whether the bottom brackets would be compatible. As far as I'm concerned the bike I want to buy has press fit bottom bracket. I don't really know what that means.

But if I get that bike would I be able to swap the cranksets over on their own? or how I could sort this out? new bottom brackets, adapters ?

Another thing is that my current bike has front der clamp on with 31~mm diameter and the new one has 27~mm. Would this mean that I would have to buy entire new front mech with the clamp, or just a clamp?

Any advices on this will be appreciated. Thanks :)

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bernithebiker
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Joined: Mon Nov 19, 2012 14:54 pm

Re: bottom bracket confusion

Postby bernithebiker » Mon Dec 17, 2012 08:53 am

There are adaptors to allow GXP type cranksets to be used with different press fit (like BB30) frames. But without knowing which frame, it's hard to say, as there are many different press fit standards, BB86, etc. It's a minefield.

Best thing probably is sell the old SRAM Red, and buy a new one that matches the new frame. Much less headache.

Front mech, don't know for sure, but probably need new one.
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Bespoke and 5* cycle trips based in Palma, Mallorca.

kamil1891
Posts: 604
Joined: Thu Mar 24, 2011 16:59 pm

Re: bottom bracket confusion

Postby kamil1891 » Mon Dec 17, 2012 10:12 am

Alright, I understand now :) Thanks.

The thing is that the groupset separately would cost me almost as much as the new bike with it, that's why I'm thinking how to sort this out :) http://www.bike-discount.de/shop/k1847/ ... ml?mfid=52

but is it not possible to remove the press fit bb and replace it with GXP? I've seen that the frames separately are sold without bb. http://www.bike-discount.de/shop/k326/a ... ml?mfid=52

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Monty Dog
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Re: bottom bracket confusion

Postby Monty Dog » Mon Dec 17, 2012 14:07 pm

What type of press-fit BB? BB86/90 and GXP use the same configuration of crankset whereas BB30 uses a different spindle arrangement - BB30 cranks only work with BB30 because of the bottom bracket arrangements, but you can you use a GXP crank in in BB30 with an adaptor.
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kamil1891
Posts: 604
Joined: Thu Mar 24, 2011 16:59 pm

Re: bottom bracket confusion

Postby kamil1891 » Mon Dec 17, 2012 14:37 pm

I have no idea what type of press fit bb that is, that's why I've posted the link to the bike. But as far as I can see it doesn't state anywhere.

So, does it mean that as long as it's not BB30, then I can simply remove the sram red 2013 crank of that bike and put it into my other bike with GXP bottom bracket and vice versa ?

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bernithebiker
Posts: 3371
Joined: Mon Nov 19, 2012 14:54 pm

Re: bottom bracket confusion

Postby bernithebiker » Mon Dec 17, 2012 15:03 pm

Looks like it's BB90 (see below the frame picture).
http://www.cyclespeedtours.com

Bespoke and 5* cycle trips based in Palma, Mallorca.


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