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How to tell if a Sram Red crankset is GXP or BB30

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How to tell if a Sram Red crankset is GXP or BB30

Old 01-20-16, 08:02 AM
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How to tell if a Sram Red crankset is GXP or BB30

I am looking at a Sram Red 10 speed compact crank on line. The seller does not know if it is BB30 or GXP.

I have pictures but what do I look for?

I have searched this and it is hard to get this information.

Thanks
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Old 01-20-16, 08:26 AM
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Easiest litmus test I can think of is that gxp steps down from 24mm to 22mm on the splined side. On bb30 the splining starts without a step. Also the bb30 is turned for bearing contact in two spots of the same diameter, while gxp is turns for bearing contact in two spots of different diameters (and often on the splining)

Also the bb30 axle is... 30mm while the gxp is 24mm. That's 20% larger- it should be easy enough to eyeball if you use google image to calibrate your dead reckoning.

Post the pictures.
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Old 01-20-16, 09:55 AM
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Definitely the spindle is 24/22mm on the GXP and the BB30 will be 30mm.
I'm not 100% sure but my impression is that on GXP cranks the non-drive arm is removable and on BB30 the drive side is removeable.
A BB30 spindle should have a threaded adjuster ring on the spindle for adjusting preload.
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Old 01-20-16, 10:42 AM
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Originally Posted by Slash5
Definitely the spindle is 24/22mm on the GXP and the BB30 will be 30mm.
I'm not 100% sure but my impression is that on GXP cranks the non-drive arm is removable and on BB30 the drive side is removeable.
A BB30 spindle should have a threaded adjuster ring on the spindle for adjusting preload.
This has always been my experience as well. I'm not sure if that's the case for every crank model, but I think you could reasonably determine compatibility based on this info in addition to having photos.
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Old 01-20-16, 11:05 AM
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Originally Posted by IthaDan
Also the bb30 axle is... 30mm while the gxp is 24mm. That's 20% larger- it should be easy enough to eyeball if you use google image to calibrate your dead reckoning.
A difference this dramatic should be detectable with an ordinary ruler. The seller should easily be able to tell you what he has.

Reminds me of the joke about the two farmers who couldn't tell their horses apart. So they measured them very carefully and found the white horse was 1" taller than the black horse.
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Old 01-20-16, 11:24 AM
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My only concern with having the seller measure (and why I didn't suggest it)- as is often the case here with Craigslist ads and such- is that sellers seem to rarely be near the parts or a camera or even have simple measuring tools.
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Old 01-20-16, 03:07 PM
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Thanks Guys, I will try and cover all the bases with this
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