60 years now I have used Clips, straps and cleats, along with a single fixed gear for most of the time, To date, I have had No knee problems or any other leg related problems, So I must have been doing something right, PLUS I have received many compliments on my smooth pedaling style. Living in the mountains and doing a LOT of hill climbing, been strapped in enables me to drop the heel and use the full stroke of the pedal, watch the TDF riders see how they use the full cicle when pedaling the heel droping on the down stroke.. NOW around town and not under any pressure to perform, I do not FULLY tighten the straps, just enough to step out if needed. The chaps I ride with all say "Look out Crumpys tightening his straps" 'Lets rock and roll chaps". Different strokes for different folks I guess, do what works for you, BUT one thing, allways ride in the lowest gear you can, the Knees are the most important part of your body in cycling. Cheers John Crump OldkneesstillokBrit, Parker. Co USA