Excellent point. And, one that as a Frog user, I missed. I can understand the large amount of extra "tainted float" angle needed when releasing from a CB or SPD pedal - I'm assuming that's when the cleat is working against the spring and forcing open the attachments on the pedal. Makes sense that this would be a fairly long arc to keep the torque on your knee at a minimum.

Frogs are quite different though. The pedal has no spring, that function being handled by a vary small elastomer in the cleat assembly. Frogs also release one-sided only. Their pedal float itself (untainted) is very large, something like 20-22 degrees. Their locking cam design makes the "tainted" float very small in comparison (I'd estimate only a couple degrees or so. The release is very fast and smooth - there is almost no resistance at the release point. It's just a quick twist and you're out.

So on a CB/SPD pedal, to release, one would move through a small free float arc, then a much longer arc during which the pedal is releasing. And staying within the free arc does not affect the release mech at all. On a Frog, the end of the freefloat arc and the actual release point are much closer together and without the transition during which you work against the pedal spring.

Based on what I've seen, when mfgrs talk about "float" they are talking about free, "untainted" float only.

Great information, everyone! It appears that I should strongly consider the Speedplay Frogs. More than I wanted to spend, but I really want to avoid getting discouraged by painful knees like I did when I tried starting a jogging regiment a while back.

Any good places to pick up a used pair besides the For Sale forum here and Ebay?

I use SPD style pedals on my commuter bike, and they have a reasonable amount of float. Not as much as some pedals but it's not like your feet are locked in place. The importance of float is vastly over-rated, and depends on each person. I tried some Speedplay pedals for a while, which have tons of float, and they actually caused me to have knee pains. I had to return them after two weeks because I was afraid they were going to cause knee injuries. More important than float is having your cleats properly positioned and aligned on your shoes and pedals.

I checked some online reviews of the Frogs and it appears that the quality has gone down quite a bit in the last few years. Perhaps I'm back to leaning towards the Time Aliums.

Paul, my $.02 is that float isn't as important as getting the angle and tilt (pronation?) in the ball park and WARMING UP before any effort and cooling down after your ride with a walk instead of immediately sitting in a chair. I rode a lot before clipless pedals and as much as cleat position was important HOW you used your legs had more to to with injury and recovery than the particular equipment.