Truvativ gxp BB

Discuss light weight issues concerning road bikes & parts.

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jrennie
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Location: Reno, NV

by jrennie

Anyone have any experience with these BB? I need to replace my cranks and was going with an external bearing design. The GXP bb weighs in at 115g which is even lighter than my ac which is kinda nice since my new cranks weigh a little more than my fsa carbon pro.

geraintnorman
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by geraintnorman

jrennie wrote:Anyone have any experience with these BB? I need to replace my cranks and was going with an external bearing design. The GXP bb weighs in at 115g which is even lighter than my ac which is kinda nice since my new cranks weigh a little more than my fsa carbon pro.


I think you can use the Shimano BB - I did this with an FSA chainset and saved 45g.

by Weenie


jrennie
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Location: Reno, NV

by jrennie

Will the sram force crankset have any problems fitting the Shimano BB?

rbrtwyn
Posts: 253
Joined: Thu Dec 09, 2004 1:57 pm

by rbrtwyn

I think that Sram uses a different style BB than Shimano. Something with the spacing or spacers or something like that, maybe someone can help me out?

RollinOn27s
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Joined: Thu Oct 06, 2005 4:17 am

by RollinOn27s

SRAM/Truvativ cranksets require a SRAM/Truvativ GXP bottom bracket. They are not compatible with shimano or FSA bottom brackets. The diameter of the hole on one side is slightly smaller than the other with the SRAM BB, whereas the shimano BB has both sides the same size.

Tristan
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by Tristan

RollinOn27s wrote:SRAM/Truvativ cranksets require a SRAM/Truvativ GXP bottom bracket. They are not compatible with shimano or FSA bottom brackets. The diameter of the hole on one side is slightly smaller than the other with the SRAM BB, whereas the shimano BB has both sides the same size.


To expand on this:

SRAM / TV cranks work only with SRAM / TV bottom brackets
Shimano, FSA or Raceface cranks are all interchangable and will work with any Shimano , FSA or Raceface bottom bracket.
Wheelworks.co.nz
New Zealand handbuilt wheels

flipflopper
Posts: 33
Joined: Sat Jun 11, 2005 7:56 am

by flipflopper

Thanks for the clarification.

So, is the spindle on the Truvativ/Sram crankset not the same diameter across its whole length? Is it tapered? Why the two different designs?

And, two more related questions:

Which camp is Bontrager in? What about the Rotor Agilis? Is there a way to tell just by looking at the crankset?

And, here's my bigger question: On the Quarq website store, it says:

Note! The FSA Team Issue crankset works ONLY with this
bottom bracket. NOT with any other MegaExo bottom braket.
Select English or Italian.


What could that be about?

footwerx
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by footwerx

The rotor agilis is in the shimano camp.

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rc32
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by rc32

flipflopper wrote:Thanks for the clarification.

So, is the spindle on the Truvativ/Sram crankset not the same diameter across its whole length? Is it tapered? Why the two different designs?

And, two more related questions:

Which camp is Bontrager in? What about the Rotor Agilis? Is there a way to tell just by looking at the crankset?

And, here's my bigger question: On the Quarq website store, it says:

Note! The FSA Team Issue crankset works ONLY with this
bottom bracket. NOT with any other MegaExo bottom braket.
Select English or Italian.


What could that be about?


Bontragers are made by Truvativ/SRAM. That's why they say GXP.

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holycao86
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by holycao86

Zinn has an article on Velonews that is about a month old that talks about pretty much everything you would need to know about bottom bracket cup compatibility.

But in short: Shimano works with shimano only. SRAM and truvativ all use the GXP, and bontrager cranks are made by truvativ (the carbon models even look practically identical). they do not fit shimano straight up because the NDS axle tapers down a bit, but you can make it fit with shims/spacers. FSA has their megaEXO bracket which works with certain shimano ones but not all apparently. but for some real bling, you can get some shimano-compatible chris king BB cups.

but i believe you asked about how well the GXPs work. i have two GXP BBs (one with a rival crank, one with a stylo crank) as well as two shimano BBs (one with an ultegra crank, one with XTR). i like the GXP's much more than the shimanos. they are much easier to work with, because GXP compatible cranks all have self-extracting crank arms. the tapered side of the axle creates a shoulder that the crank arm gets tightened against, therefore not allowing the bearings to be overloaded. the shimano cranks, however, do allow adjusting the bearing preload, but i can never find that damned plastic splined wrench that you have to use.

flipflopper
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Joined: Sat Jun 11, 2005 7:56 am

by flipflopper

Here is link to the two articles holycao mentioned:

http://www.velonews.com/article/86692/

http://www.velonews.com/article/86337

It is getting more complicated. There aren't even just two types of bottom brackets.

FSA itself is making at least two different kinds for its various cranksets.

And another interesting thing to figure out: it's Team issue crankset looks extremely similar to the bontrager / truvativ / sram crankset. So i'm not totally clear what it is compatible with.

I hope with BB30 everything is compatible with everything.

Steve928
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Location: UK

by Steve928

holycao86 wrote:GXP: the tapered side of the axle creates a shoulder that the crank arm gets tightened against, therefore not allowing the bearings to be overloaded. .


That makes it sound as if the GXP axle has a fixed length. So how does GXP cater for the the tolerance in BB shell widths and still get the correct bearing preload? (the UT wavy washer scenario..)

by Weenie


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holycao86
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by holycao86

i actually had this same question myself. that shoulder is both what i read and what looks like is happening. i'm really not sure how it is that it can account for BB width tolerances.

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