Bottom Bracket Replacement?: 2023 S40

[Terrarium]

Upgrading to SRAM Apex 1x11, installed GXP BB fine, but when I install the SRAM apex crank and attach the non-drive side crank arm, the whole crank gets tight and stops freely spinning.

The GXP comes with 2 spacers that i've put on each side of the BB, per the install manual. Is there some eccentricity I'm missing here or something silly?

GXP Bottom Bracket - BB-GXP-A1 - SRAM

GXP Bottom Bracket, BB-GXP-A1, SRAM. Gutter Seal Technology drastically improves sealing against the elements while reducing seal drag. Weve designed a fresh cup forging for a high-end l...

www.sram.com

 

[cruzKurt]

Upgrading to SRAM Apex 1x11, installed GXP BB fine, but when I install the SRAM apex crank and attach the non-drive side crank arm, the whole crank gets tight and stops freely spinning.

The GXP comes with 2 spacers that i've put on each side of the BB, per the install manual. Is there some eccentricity I'm missing here or something silly?

GXP Bottom Bracket - BB-GXP-A1 - SRAM

GXP Bottom Bracket, BB-GXP-A1, SRAM. Gutter Seal Technology drastically improves sealing against the elements while reducing seal drag. Weve designed a fresh cup forging for a high-end l...

www.sram.com

Glad you posted this, I had a similar problem, I could install an APEX crankset no problem, but when I tried to install another crankset I had laying around it was free spinning until really tightened down on it. it seemed to me that the non drive side crank arm was binding against the BB, meaning if I shaved it off a bit, I would be able to completely tighten it. I did not go there, but it seems the entire BB is a bit wide for the crankset (probably only .030" or so if I had to guess.) seems the spacers are too thick or something similar.

 

[Robert Holler]

Since "standard" is a word thrown around in the bike industry that is 1000% meaningless by its definition, things are always a bit off when mixing parts like this - and sometimes just when there are differences on some bb shell specs. A BB cup spacer kit like below is what you need to reduce one or the other side.

https://wheelsmfg.com/products/bottom-bracket-parts/cup-spacers.html

 

[cpml123]

Upgrading to SRAM Apex 1x11, installed GXP BB fine, but when I install the SRAM apex crank and attach the non-drive side crank arm, the whole crank gets tight and stops freely spinning.

The GXP comes with 2 spacers that i've put on each side of the BB, per the install manual. Is there some eccentricity I'm missing here or something silly?

GXP Bottom Bracket - BB-GXP-A1 - SRAM

GXP Bottom Bracket, BB-GXP-A1, SRAM. Gutter Seal Technology drastically improves sealing against the elements while reducing seal drag. Weve designed a fresh cup forging for a high-end l...

www.sram.com

Oh wait... this is interesting. I have a 2017 S40 with GXP BB. There are no spacers installed. The crank is Cobbs and spins freely.

I also have a 2018 V20 with GXP BB and no spacer installed. The crank is BBK. It doesn't spin as freely as the S40. It originally came with Ultegra BB and crank, also doesn't spin as freely as S40.

@Robert Holler I guess in the V20's case, does that mean the V20's BB shell is slightly too wide because I didn't use any spacers to start with? It's interesting because I thought S40 and V20 use the same front end BB thingy. Slight manufacturing difference between batches?

 

[Robert Holler]

Oh wait... this is interesting. I have a 2017 S40 with GXP BB. There are no spacers installed. The crank is Cobbs and spins freely.

I also have a 2018 V20 with GXP BB and no spacer installed. The crank is BBK. It doesn't spin as freely as the S40. It originally came with Ultegra BB and crank, also doesn't spin as freely as S40.

@Robert Holler I guess in the V20's case, does that mean the V20's BB shell is slightly too wide because I didn't use any spacers to start with? It's interesting because I thought S40 and V20 use the same front end BB thingy. Slight manufacturing difference between batches?

It is more frequently the difference in the BB cups and the accompanying spindle on the crank, but I have seen some actual shells that can have a +/- 1mm variation. Also I have seen some shells that have been faced more than once which shaves a bit of material off every time, thus possibly necessitating the use of a spacer or two of various widths.

Some bb's are actually designed to be used with spacers in order to adjust for a proper chainline - you might use one spacer on each side or both on one or the other, etc...

A good shop should have a slew of various width shims you can grab. I have also (not on a Cruzbike but just random bikes built over the years) had a binding crank where there were no spacers and I had to face the sides of the BB shell to get that tiny bit of extra relief to allow for a smooth spin.

 

[Terrarium]

I think folks I'm just going to try and install it WITHOUT the shims. It seems everyone's saying that these widths aren't always as precise as would be desired.

 

[Robert Holler]

I think folks I'm just going to try and install it WITHOUT the shims. It seems everyone's saying that these widths aren't always as precise as would be desired.

Give it a shot. You might only need to remove one spacer, and place that spacer on the side that gives the best chainline.

 

[Terrarium]

Installation with one spacer on drive side worked fine. The illustration in SRAM's manual made it difficult to understand.