I, too, would like to know about any bad reviews that Speedplays (X, Frogs, Zero) have gotten. I would speculate that the bad reviews are of the "a friend of a friend says that..." variety.

All I know is that my knee problem (not a severe one) went away when I switched from SPDs to Speedplays.

Although I am only known to run when chasing a soccer ball, my fiancée is a runner (she rides a bike only to the store and such). The only time she has orthopedic problems from running is when she pushes her training too much. Her books on the subject all stress raising your distances slowly to allow the body to adapt orthopedically (which takes much longer than the cardio-vascular system).

It is no secret that running is harder on the joints than cycling or swimming, but you have to wonder whether the injuries don't come more from bad technique, an accelerated training regimen, or some pre-existing condition.

My dad had to quit running due to a bad knee, but the original injury was actually caused by a long mountain climb on a sideways slope, followed the next day by 5 sets of tennis.

After all, primitive human beings ran out of their burning huts and away from chasing tigers--they didn't ride bikes (the poor things).

Cheers,
Jamie