This is my first encounter with one of these, surprisingly: had plenty of experience with tapers (as well as the old cotterpins - yonks ago! ). Anyway, I know splines are commonplace these days: my son's left crank loosened and fell off today on the ride. He managed to re-attach it, and I had a look this evening and tightened it a bit more. My question is: how tight? There are two allen bolts holding the thing on. I'm forever scared of stripping threads. Any other tips?