I used Zeros for a couple of years and liked them for all the reasons others have stated. No longer. They wear out relatively quickly resulting in slop between the pedal and cleat. This is manifested by a side-to side rocking motion of the shoe over the pedal.
The problem with the Speedplays is that the pedal body wears down rather quickly due to the abrasive action of the dirt which gets trapped between the pedal and cleat. Also, the plastic plate inside the cleat, which is the primary weight and friction-bearing surface that the pedal rides and turns on, is subject to the same wear as the pedal, only it is at a significantly greater rate as it's composed of a softer material than the pedal body and really shows the wear. It develops rather deep indentations that are the mirror-image of the pedal itself, as the pedal is constantly rotating against this surface. If there is the smallest amount of grit between the pedal and the cleat, the wear action and subsequent slop is accelerated significantly.
One cannot tell by looking that the pedal body is wearing until it's too late. A dial caliper is required to measure the thickness of the pedal. The outside portion of the pedal is the location of the greatest wear (this is the 3 o'clock position, looking down from the saddle, for the right side, 9 o'clock for the left). When new, the pedal body thickness is .675". Seven months after initial installation, the pedal bodies had worn down to .635", a full .040"! This is about the thickness of the wire that a large paper clip is made of. (It's a lot of wear). The cleat plate had indentations that were .070" deep! When I clipped in, there was all kinds of slop, as the total gap was around .110". I have found that the pedal starts to feel sloppy when the outside of the pedal body has lost around .010". Bear in mind that the cleat will have at least the same amount of wear and usually more (say .015" or so). One feels the wear as a tendency for the foot to roll to the outside. It really doesn't take much wear to feel this sloppiness, and it snowballs once it has started. The gap between the pedal and cleat gets bigger and the slop gets worse. Keeping this pedal/cleat system spotless at all times is critical if you want any longevity.
I switched to Shimano Ultegra pedals with the blue cleat and have never looked back. The stability is rock solid, the float is perfect, AND there is simply no cleat better for walking around.
Just my .02c. Your mileage may vary.
The problem with the Speedplays is that the pedal body wears down rather quickly due to the abrasive action of the dirt which gets trapped between the pedal and cleat. Also, the plastic plate inside the cleat, which is the primary weight and friction-bearing surface that the pedal rides and turns on, is subject to the same wear as the pedal, only it is at a significantly greater rate as it's composed of a softer material than the pedal body and really shows the wear. It develops rather deep indentations that are the mirror-image of the pedal itself, as the pedal is constantly rotating against this surface. If there is the smallest amount of grit between the pedal and the cleat, the wear action and subsequent slop is accelerated significantly.
One cannot tell by looking that the pedal body is wearing until it's too late. A dial caliper is required to measure the thickness of the pedal. The outside portion of the pedal is the location of the greatest wear (this is the 3 o'clock position, looking down from the saddle, for the right side, 9 o'clock for the left). When new, the pedal body thickness is .675". Seven months after initial installation, the pedal bodies had worn down to .635", a full .040"! This is about the thickness of the wire that a large paper clip is made of. (It's a lot of wear). The cleat plate had indentations that were .070" deep! When I clipped in, there was all kinds of slop, as the total gap was around .110". I have found that the pedal starts to feel sloppy when the outside of the pedal body has lost around .010". Bear in mind that the cleat will have at least the same amount of wear and usually more (say .015" or so). One feels the wear as a tendency for the foot to roll to the outside. It really doesn't take much wear to feel this sloppiness, and it snowballs once it has started. The gap between the pedal and cleat gets bigger and the slop gets worse. Keeping this pedal/cleat system spotless at all times is critical if you want any longevity.
I switched to Shimano Ultegra pedals with the blue cleat and have never looked back. The stability is rock solid, the float is perfect, AND there is simply no cleat better for walking around.
Just my .02c. Your mileage may vary.