Originally Posted by
Monkeyfudger
If the spider on the Rotor’s is bolted on like their road cranks then I’d put that purely down to user error and not tightening the bolt enough.
I have a Rotor/P2Max Track crank (uses the Road 3D arms). The Spider fits over a spline on the drive side arm and is held in place by a lock ring. Common assembly method used on other cranks, for example Cannondale Hollowgram.