I'm a big sprinter that originally got into the speedplay X2 simply because I heard they were good for my knees. I'm not so sure I need all that float for my knees since there not bad to begin with. What kind of pedals do you sprinters use? I feel like I may be losing some watts with the extra float in the speedplays and my feet sliding around a bit in internal and external rotation of my heel/tibia.

I'm a big sprinter that originally got into the speedplay X2 simply because I heard they were good for my knees. I'm not so sure I need all that float for my knees since there not bad to begin with. What kind of pedals do you sprinters use? I feel like I may be losing some watts with the extra float in the speedplays and my feet sliding around a bit in internal and external rotation of my heel/tibia.
I doubt that you're losing much wattage, but if you're looking for a different style pedal, Speedplay Zeros may work better, or if your knees are only marginally bad, you're fine with anything, really. Look Keos are excellent, I don't have the best knees in the world... lots of people ride these pedals for a reason. Tom Boonen rides Time pedals, so those must be good, etc.
Really, any modern pedal wont lose you any wattage unless you've got a very interesting pedal stroke.
-estone2

You might also want to check the cleats on those; they wear fast and get progressively sloppier. Just replaced my X2 cleats yesterday after 5000 miles and the difference was huge. I'm a big guy that likes to play in the sprint and like the Speedplay for it's easy clipin and good cornering clearance (I used to scrape my Looks pedaling in corners). I think the knock on the Speedplays is their tendency to produce hotspots compared to a wider platform pedal like the Look and the problem hooking them up to big Sidi shoes. They just make it on my 48's.

chris

Track Sprinters? They generally use old SPD-R pedals with double straps (or a similar setup). Track Sprinters are crazy though, and a foot out of the pedal means a high speed crash. On the road, use whatever feels comfortable for you. I've gotten to like my Speedplay Zero CrMo pedals. I can adjust everything on them and I haven't popped out yet (which is more than I can say about any other pedal system I've used).