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Discussion Starter · #1 ·
I’ve got some X0 GXP cranks that I’ve had for ages, they recently developed play so assumed the BB needed replacing. When I took the old BB out it didn’t seem too bad, bearings actually felt ok but the new one went in anyway, but there is still play, never had this before.

Any ideas? I’ve seen posts on the web that some people have used the wavy spacer with press fit BB to eliminate play, but not with GXP.

It’s definitely tight enough, I’ve replaced about 5 or 6 BBs on these cranks and never had this before.


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How is the play manifesting itself? Axial play of the crank spindle? Radial play of the crank in the BB bearings? On one side? Both sides? Etc.

Also what brand were the previous BBs that worked fine and what brand were the last two that didn't?

And lastly, what torque are you doing up the NDS crank side to?
 

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Discussion Starter · #3 ·
Not sure on axial etc, but with the crank at 12 o’clock you can feel the play when pushing/pulling towards the seat tube. From both sides.

Bottom brackets have always been Sram GXP team. Torque wrench goes up to 20nm and it’s way beyond that. Having had the cranks on and off numerous times I get the feel for how tight they need to be, but this time I just cannot get them any tighter!


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Sram GXP BBs have a couple of weird "design features". On the drive side they use a bearing with an inner race diameter of 25mm while the crank spindle on DS side is 24mm. You have to install the plastic sleeve / dust cover that comes with the BB by pushing it into the DS bearing. This sleeve reduces the ID to 24mm. This sleeve can work its way out if there are no spacers or wavy washers on the DS (not supplied with the BB) and then you get play. Even if it comes out a little. Usually it will hit the chain ring before it comes out fully. See my posts in this thread:

https://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/gxp-bb-issue-912605.html

The other weird thing about them is that the NDS inner race diameter is 22.20mm, while the NDS Sram crank spindle diameter is 21.95mm, giving you 0.25mm of play. My video below demonstrates this. I sent it to Sram asking to explain how it's supposed to work like that. Their reply was to just go ahead with the installation and ensure the crank is tightened up to spec (54Nm) and the play will go away. 54Nm is a lot of newton meters. I think I got up to about 45Nm and called it a day. You need a big wrench to do that. A torque wrench that maxes out at 20Nm will be too small for this.


Using the high torque and some spindle spacers on the DS to stop the plastic sleeve from coming out has worked for me for the last few years.
 

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I had a set of SRAM 1x cranks where the press fit spindle came ever so slightly loose from the drive side crank arm. Felt like it wasn't tightened down enough. I removed it and you could feel the play between the spindle and crank arm. SRAM warrantied it and sent me a new one. Something to check anyway.
 
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