These cranks from Qu-Ax are designed specifically for their Q-Axle hub.
The splined system means that the cranks are no longer tightened as much on the axle as possible - but precisely positioned by an alloy cap and then fixed by tightening 2 allen-key-screws on the crank. The crank-connection has less wear and is more resistant to frequent assembly/dissassembly. Also, just like from tapersquare to ISIS interface, the connection-surface that transfers the pedaling-power is bigger.
Note: These cranks will not fit on ISIS hubs, they will only fit on the Qu-Ax Q-Axle hub
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