I think the idea of this design is that the 8mm bolt tightens up against the axle, thus pushing the crank to exactly the right position to get correct bearing pre-load. This seems odd compared to other systems where you’re always tightening against the crank, and therefore have to be careful not to over tighten. So with RF cranks done up very tight, if you don’t have the correct amount spacers and a well faced BB shell, you will crush the bearings or not apply the correct load, i.e. tightening up more doesn’t keep pushing the crank arm inwards. Grinding a few mm off the axle might work, but you’d need to remove chainline spacers to compensate otherwise you’ll crush the bearings.
My Atlas crank did come loose the other day, simply because I’d not tightened the 8mm bolt after refitting it. I only noticed after an hour of hammering up and down Jacob’s Ladder, so I expected the worst. However, once back home, I completely degreased the axle and bolt threads and all splines, dried it all, refitted it with loads of loctite and did up the 8mm bolt with a huge amount of torque (it’s all steel, so won’t break). It’s been OK since then, so I think I may have saved it all. If this fails, I will resort to grinding back the axle a bit.
