SRAM GXP installation question

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G1032
Posts: 32
Joined: Mon Jul 27, 2020 7:49 pm

by G1032

TobinHatesYou wrote:
Fri Mar 10, 2023 2:25 am
He’s saying the splined interface isn’t sticking out enough even though the step in the spindle is butting up against the bearing on the other side. I can see how that would prevent the NDS crankarm from being able to hit its torque spec. Essentially he isn’t achieving an interference fit because the tapered interfaces aren’t meshing fully.
Yes. Exactly this!

G1032
Posts: 32
Joined: Mon Jul 27, 2020 7:49 pm

by G1032

eins4eins wrote:
Fri Mar 10, 2023 7:31 am
In the video, the dimensions seem fine. Crank sticks out enough on the NDS.

This is what a Sram BB Dust cover looks like. There are steps so that the dust cover only presses against the inner ring of the bearing and has no contact to the outer casing of the bearing. Maybe check your dust cover or show some pics of your NDS assembly.

Image

Image
These are the pics of the NDS assembly
https://1drv.ms/u/s!Akk2mjjNlxAbgesiTWx ... Q?e=fEA8EH

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TobinHatesYou
Posts: 12456
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

My assumption right now is that the BB itself is not made to the correct dimensions.

G1032
Posts: 32
Joined: Mon Jul 27, 2020 7:49 pm

by G1032

TobinHatesYou wrote:
Fri Mar 10, 2023 12:41 pm
My assumption right now is that the BB itself is not made to the correct dimensions.
Mine too. I have mailed the retailer I purchased from so let's see what they say. I have my Shimano cranks back on so not stuck without the bike.

G1032
Posts: 32
Joined: Mon Jul 27, 2020 7:49 pm

by G1032

eins4eins wrote:
Fri Mar 10, 2023 7:31 am
In the video, the dimensions seem fine. Crank sticks out enough on the NDS.

This is what a Sram BB Dust cover looks like. There are steps so that the dust cover only presses against the inner ring of the bearing and has no contact to the outer casing of the bearing. Maybe check your dust cover or show some pics of your NDS assembly.

Image

Image
Conatcted the retailer that I bought the Katana BB from
Explained the issues I was experiencing. I was given a refund with instruction not to send the BB back.
Bought a SRAM BB instead this time. Installed last night. No issues. Spinning perfectly.
The major difference I can see between the 2 BBs is the NDS bearing shield. The one on the picture posted by eins4eins above is what's on the new SRAM BB I have. Shield on the Katana NDS is a more conventional style.
The exposed part of the spindle measures the same with each BB but the SRAM bearing shield seems to prevent excessive load being put on the bearing while the Katana one doesn't (even though it is stepped)

bmCube
Posts: 122
Joined: Wed Jan 05, 2011 8:37 pm

by bmCube

I had the same issue. Tried to install a gxp crank in a shimano bottom bracket with the use of an adapter, that's installed from the inside. I had to install 1cm of spacers on the drive side to make it work, but the chainline was way out. So removed the adapter and saw that the part that comes against the nds spindle was pretty thick, compared to other adapters. So I removed very much material, installed it again and worked perfectly.
Does your bottom bracket have a adapter installed from factory, or is the bearing stepped? If there's an adapter, I would remove it and try another one, with less thickness.

My adapter was like this: So the thicker part was wider


Image


now it's more like this one: thicker part is less wide


Image

G1032
Posts: 32
Joined: Mon Jul 27, 2020 7:49 pm

by G1032

bmCube wrote:
Fri Mar 17, 2023 12:48 pm
I had the same issue. Tried to install a gxp crank in a shimano bottom bracket with the use of an adapter, that's installed from the inside. I had to install 1cm of spacers on the drive side to make it work, but the chainline was way out. So removed the adapter and saw that the part that comes against the nds spindle was pretty thick, compared to other adapters. So I removed very much material, installed it again and worked perfectly.
Does your bottom bracket have a adapter installed from factory, or is the bearing stepped? If there's an adapter, I would remove it and try another one, with less thickness.

My adapter was like this: So the thicker part was wider
No adapters. Just a BB that wasn't very well desidned.
Lesson learned. Thought I was getting a good deal on a ceramic bearing BB at a good price.
Bought a SRAM BB and it worked perfectly out of the box. No spacers needed.

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