Originally Posted by khuon
Speedplay binding mechanisms are complex? Surely you jest. The Speedplay Zero and X pedals have one part that moves and it's a captive spring or C-clip. There are no linkages. The mechanism is elegant and simple. In contrast, other pedals have hinged jaws and linkage mechanisms. The Speedplay Frogs just use a small elastomer bumper at the edge to act as a spring for the locking tab. There are no other moving parts. Yes, the coatwire hanger spring in the Speedplay X cleats can get gummed up but so can the SPD and Look pedal jaws. The Zero cleats use a flat C-clip thus alleviates a lot of contamination sensitive problems. You can of course still pack mud into the cleat cavity. I regularly walk through gravel and muddy roads on my Zero cleats and haven't had a problem.
I have not tried the Speedplay Zeros -- maybe you've used them and had better luck with them, but I can't comment on them. The Frogs were not unreliable. Shannon just had some problems with early release on those that the shop couldn't resolve, so she gave up on them.
However, we've been through 2 pairs of the Speedplay Xs and I think after several hundred miles I can give my opinion on them without jest: they are unreliable. The wire in my Speedplay Xs gummed up more than once, as have Shannon's. The problem is simple, but annoying, to fix. I have never had the problem with the Shimanos or (subsequently) the Keos. I think placing the binding mechanism on the cleat instead of the pedal isn't a good idea. While it is true that the pedals jaws on Shimano and Look pedals can also get gummed up, mud is more likely to be forced into the cleat than the pedal. I put probably 10 times the miles on the Shimano R600s than I did the Speedplays, without a single problem except needing to replace the cleats for wear. Not one single failure. The Speedplay Xs are the only pedals I have ever bought for which the shop automatically recommended cleat covers. Muddy cleat covers are a real joy to stuff into your jersey pocket next to your Hammergel flask.