I had problems with my one knee. I switched to a pedal that has max float of 9 degrees (adjustable) got them put on and aligned properly by the guy at my LBS no more Knee problems. For me proper alignment and a pedal with less play is the answer.

Ok, here's the deal. Back when we used cleats and toe clips with straps, there was ALWAYS a high degree of flexibility, both in heel arc, and in the shoe itself, no matter how tight you pulled the strap. The strap and cleat only locked in along a thin edge at the back of the pedal. This slot/edge combo had a relative degree of slop in it, reinforced by the fact that the strap locked you down straight across it, creating a slight pivot point, giving you, in effect, heel arc. It wasn't as much as some systems today, but it was enough. Second, the shoes of yesteryear were infinitely more flexible than even the most flexible on the market today. The uppers were leather and the soles were thin nylon and even leather before that. This flexibility in the shoes made up for the needs of the pronators/supinators who needed their feet to rock either way during the pedaling motion. Locking the strap tight would limit, but not fully prevent such motion.

Fast forward to the advent of clipless pedals. These systems provided such a positive lock between pedal and shoe that the only motion allowed was in the shoe. We quickly found out that the current shoe designs of the time were inadequate and often wore out too quickly because so much stress was now transferred to the build of the shoe, the stitching, and the sole. I once saw a powerful sprinter friend of mine nearly rip the upper completely off the sole during a crit sprint finish. So shoe companies beefed up their uppers to compete with these stresses. Of course now we had two follow-on problems. First, the soles were the only place motion was allowed. Cyclists quickly realized that a stiffer sole was better for capturing their power output. Voila, the soles got stiffer. But now we had this entire ridgid system with feet locked into a stiff pedal and shoe combination. Riders weren't long in discovering that correct cleat alignment was imperative in preventing knee problems. Or we needed some "slop" added judiciously back into the system.

Enter the arc systems. Now we have the ability to move our heels side to side again. But the pronator/supinator crowd still needs help. So we shim their cleats one way or another. We now have super stiff carbon fiber soled, shoes that transfer our power efficiently and effectively to the bike's drivetrain. So today, arc systems help alleviate the need to be 100% correct in your cleat alignment (though its still preferable), and the only way to provide for rocker type motion needed by the pronator/supinator crowd is to use shims.

If you are using arc type pedal systems and still have knee problems, there are still many reasons for it. You might need shims. Your cleat may be too far forward/backward with respect to the pedal axle. Your saddle height may be too high/low. You may have adjusted the saddle height too quickly. You might be piling on too many miles too quickly. But I seriously doubt that having arc of any degree or freedom will contribute in the slightest to knee pain.

I recommend you go with a free floater system like the Speedplays (unlike Look and others with "self-centering" cleats) and get the cleats mounted with the assistance of someone knowlegeable. If you are a serious pronator/supinator, look into shims. Otherwise you'll probably be fine. With an arc system, your musculature is free to move through its natural tendency of motion. With fixed cleat and a good stiff shoe, you are locked into whatever good or poor alignment you've managed with your cleats, and your knees will have to provide any additional "slop" needed for natural motion. Take your pick.

I'm using Keywin pedals set up with zero float. I've had zero knee problems so far. They were set up by my bike fitter and I'm very happy with them. I switched over from X2 Speedplays. In comparison I *feel* more powerful on climbs (stressing FEEL so data people don't have a cow) and just feel more "oneness" with the bike. IMHO if I don't need float I won't ever go back. I think really floaty pedals like Speedplays mask symptoms of fit problems and people automatically feel that float solved their problem when a better fitting might be the answer.



On the other hand:

On my mountain bike I'll probably keep the pedals I have (ATAC) with float because when doing very slow moving balancing stuff I like to be able to turn my feet a bit.

i'm at the point where i am no longer suprised to get some great info from this site. lots of luv to all, but what about the idea that a 'rocking' motion is better for the knees?

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customerjon @gmail.com is where information happens.

It's one of the non-stop debate topics: fixed or free float.

What I find problematic is just like in the running shoe business where medially posted motion control shoes are over sold and over prescribed, in the cycling business we have the wholesale buy-in that free-floating pedal systems are the great salvation. Like most things they are good/great for some/many but NOT everyone. The triathlon community seems particularly prone to this phenomenon of the wholesale buy in: Good for the companies that some how manage to get this information across( Great Marketing) but bad for consumers who buy the product, in this case free floating pedals of some sort, and they are not the best for them.

How to sort this out: Find a reliable LBS( based on another hot thread right now this can be a challenge) and get them to help you make the best pedal/cleat choice for YOU.

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Steve Fleck @stevefleck | Blog