They don't, or at least they don't work as well as ones with the hollow centre forged in place rather than drilled. Rotor are a small company without access to the very high tech (and extremely capital intensive) forging capacity of Shimano, and that swiss-cheese crank is their attempt to achieve with cheap tools what Shimano achieve with expensive ones in terms of stiffness and weight. The process is not only inferior in terms of results, but also highly labour and time intensive, so they make a worse crank than DuraAce which is nonetheless more expensive, and would still be more expensive even if they made them in the same numbers as Shimano.
What I was thinking, can't imagine them being reet stiff.
What I was thinking, can't imagine them being reet stiff.