[Schwim Dandy]

Heya folks,

I've got a question. I've installed a GXP bottom bracket, using the spacers provided per instructions(68mm). I expected the crank spider to come into contact with the shoulder of the BB, like my Hollowtech cranks, but there's a space between the shoulder of the BB and the cranks.

Drive side

Lazy side

Drive side fitment

Lazy side fitment

It's deffo bottoming out on the lazy side. If it did go further into the BB on the drive side, I think the contact surface would no longer be on the bearing. I'm thinking maybe the space is to handle the longer bb's, like the 81mm, but wanted to ask before I start buttoning it up. Is this space good to go?

Thanks for your time!

 

[wschruba]

There will be a gap on the drive side if properly installed. A lip holds the axle to the bearing on the left side, while the drive side "floats".

 

[Schwim Dandy]

Thank you so much for your help. It's greatly appreciated!

 

[Saul Lumikko]

There must be at least a slight gap on the drive side, as wschruba said, but there's no need for it to be unnecessarily large. A very large gap means that the amount of spacers is insufficient, the cranks are not centered on the bike (left side will be inboard and drive side further from the centerline) and your chainline is outboard as well.

You can add spacers between the BB cups and shells until the gap is minimized. Add an even amount on both sides. I started with a gap similar to yours (looks like 5 mm) and reduced it to the point that I can easily insert a 0.3 mm feeler gauge between the crank and drive side BB cup.

The sideways play is eliminated by the left ("lazy") side on these GXP systems. The BB spindle has a shoulder and won't go all the way through the inner race of the bearing, and the left crank pinches the inner race from the other side as you tighten it. (The outer race is held in the BB cup with a lock ring.)

My BB shell is also 68 mm and I found the amount of spacers according to instructions to be insufficient. Rather than staring at each individual step and following them blindly, consider the desired outcome you want to achieve:

- Even amount of spacers on each side.
- Drive side gap reduced but not eliminated.

This recipe gives you proper chainline, symmetric cranks and a peace of mind.

 

[thomllama]

yup, what everyone above said basically..
Trail Tire TV: Sram's GXP Bottom Bracket, how it differs from others


if you want to understand this is the basis of how the GXP BB works.. the Newer BB cups have also been changed a bit to have extra room on the drive side so it you want to add a BB mounted chain guide there is room .. you can leave it.. it's fine.. you can put another spacer on the NON DRIVE side which will pull the chain line into the frame on the drive side the thickness of the of the spacer. if it bothers you and the chain line is good you can add one to the drive side .. it doesn't really help or hurt anything.

 

[jetboy23]

Just an observation, do you have the dust cover for the non-drive side? I'm not seeing it in the photos and just want to make sure.

 

[Schwim Dandy]

Just an observation, do you have the dust cover for the non-drive side? I'm not seeing it in the photos and just want to make sure.

I do have the washer with the inner opening that matches the splines on the non-drive side. The pics were just to show spacing, I'm not buttoning it up yet as I'm waiting on a couple more parts for the cranks.