 You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
I'm trying to fit SRAM GX 1x crank with X-sync 2 into an external GXP bottom bracket but chainring bolts are rubbing on the outside shell of the bottom bracket. Am I missing a washer or some kind of spacer (which didn't come with the cranks)
no you shouldnt need a spacer if its a MTB crank and a 73mm wide BB shell. Sounds wrong though, can you post a photo? Is it direct mount or 4 bolt with a spider? In either case there should be a few mm of axle visible between the bearing cover and the drive side crank and the crank axle should be fixed in position by the non-drive side bearing so it shouldnt be able to slide that far across.
Thanks - its direct mount. Perhaps I am just doing it wrong after years with Shimano - so I don't push the drive side crank in so its tight? Rather leave a couple of mm so it doesn;t drag on the outside shell of the BB. Struggling with pics...
You install both cups then slot the crank in from the drive side through the 'top hat' cover. It should hit a stop on the NDS bearing and then bolting on the NDS crank arm basically clamps the inside of the bearing between the crank and the step on the axle - it needs to be on tight so there is no play - there's no preload like with shimano HT2. The axle just floats in the drive side bearing and doesn't really take side load so you tend to find the BBs go on the non drive side first.
If you can be bothered then it's worth popping off the seals and packing some extra grease in there before you install them, it'll add a bit to the life span.
You should only be able to push the axle through so far, there is no adjustment on a gxp setup and there is normally a gap of maybe 5mm between the bb face and the crank on drive side. Have you got the plastic "top hat" bit in the drive side bb?
Great explanation, thanks! Not sure about what the top hat is.
Top hat is a small plastic piece that sits in the drive side bearing. It acts like a cover for the end of the bearing and the axle goes through it. It's shaped like a top hat. If you can see the metal part of the bearing then it's not there, but it might have slid across the axle and be tight up against the crank. Install it in the bb before you push the axle through.