Specifically, a SRAM Rival road crankset on a GXP BB. The frame is a standard 68mm shell.

So, cups into frame, push axle/driveside through, LH bearing cover on, LH crank on, torque up the crank bolt… no way can I get the play out of it and there’s still a good 2-3mm of axle showing on the driveside despite my best efforts to seat it with a rubber mallet.

The distance between the outer BB faces is 94mm. The distance between the inner faces of the cranks when fully torqued onto the axle is 92mm. But no mention of spacers required or indeed any included in the box.

The installation sheet just says “regrease and try again”.

What am I missing…? 😐

Firstly, your measurements will be flawed as the non-drive side crank clamps the bearing tight against the step on the axle, without the cup attached, the crank will go on further and give a false distance. This clamping of the bearing is the only fixing on these cranks, the drive side of the axle floats in the bearing(and the crank has a few mm clearance)to prevent the ham-fisted from over pre-loading the bearings as can be done with HT2 and similar types.Not sure why you’d have play though, unless the bearings(quite likely with gxp) or axle are worn, or the cups are loose

Thanks for the description of how it clamps the bearing, as you say quite different from HT2 despite looking similar.

Having done some googling it seems over-torquing initially to seat the LH crank on the splines is the trick ie. “regrease and try again, but harder”.

So with the crankset off the bike I installed/removed the LH crank on the axle a couple of times using a 1/2 inch drive socket wrench and rather more force… then tried it on the bike again and it nipped up sweetly 🙂