I'm still not sure if he has an ISIS spline or external BB. First he said his "cap" was screwed up which sounds like an ISIS spline and the cap has the center allen bolts to tighten both sides of the crank on to the BB. Then he said it looks like the one Bianchi Girl posted - external BB with allen pinch bolts on the left, but Gossamer came in both versions so maybe he doesn't know what he's looking at.



The cap on the external BB version doesn't have anything to do with tightening the crank onto the BB and it wouldn't have anything to do with the crank arm coming loose. The cap and allen bolt on the ISIS system would.