Originally Posted by 531Aussie
I'm not sure what you mean here. You may be aware that most clipless pedals have lateral "float", which means the foot and knee isn't really locked at all
Yes, some have a bit of float. But, with my big BMX pedals, I can put my feet PRECISELY where I want them, without any artificial limits. For my rare burst of fast pedaling, I can move my feet forward a quarter inch. When spinning lightly up a hill, it can feel more comfortable to move my feet back a quarter inch.
When I watch experienced riders, they never stay on the same part of the saddle. They move forward or back, depending on their needs. Moving around on the saddle helps avoid numbness and pain in that area. Moving around on pedals helps avoid foot pain and knee pain.
The "modern" pedal systems first became popular among Pro riders in the '80's. Prior to that time, knee surgery among Pro riders was somewhat rare. After they became popular, losing a season or two for knee problems or surgery became routine. Coincidence? Maybe...but I don't think so.