I've tried Sidi Ergo 2 and Specialized Pro Carbon shoes with both Keo (red cleat) and Speedplay Light Action pedals. Both combos hurt my knee after a 5 mile ride. My Lake MX-190 mtb shoes and Crank Bros Candy don't hurt my knees. I am using them on my road bike right now, but I'd like to find something lighter and dedicated for the road. Any ideas? Could the shoes be hurting my knee?!