Ok, I was going to include pix but the Speedplay site does a much better job of that.
http://www.speedplay.com/index.cfm?fuseaction=home.syzr
Backstory: I started using SPDs about 17 yrs ago when I bought my first 'bent (Catrike). I never really had any issues with them. When I went to two wheels (Optima Baron), I installed another set of SPDs...and discovered un-clip tension adjustments (never adjusted them for the trike).
I don't ever recall having any heel/ankle strike issues with the SPDs but when I started riding MBB, I started noticing that one or the other heel would sometimes rub/touch the crank arm as it went by. Never a hard hit...but annoying. I dealt with it by using block pedals, I could just shift my foot around so that it wouldn't hit. On the Conversion and on the later V2/Ks, block pedals are no problem...so I never fitted a set of clip-in pedals.
When I got the V20, I knew I was going to need clip-in (I hate the term 'clipless') pedals...but made my first rides with block pedals anyway. I noticed right away that I was getting heel/ankle strikes a lot more. I tried to take my old SPDs off of one of the V2/Ks but time (and corrosion) had welded them in place. So, I headed to my LBS to buy another set of SPDs.
While I was there, I saw a set of SYZR pedals and started looking into them. "Adjustable float" caught my eye. What I wanted was a set of pedals that I could adjust to eliminate that heel/ankle strike.
The SYZR pedals indeed eliminated the problem...but I'm not totally sold on them.
Picky #1: I'm getting used to clipping in with them...but I'm not 'on target' 100% of the time yet. I especially seem to have trouble with the left foot when starting out. I'll clip in the Right foot, give it a grunt to start and then spend the next few seconds waving my Left foot around, trying to get it to clip in. Doesn't happen every time, sometimes I step right in, done. I don't know if a set of SPDs would be better or not. I don't remember having such issues with the ol' SPDs...but I never had my feet so high up in the air either.
Picky, picky #2: takes two totally different tools to adjust them. The 'float' uses a 2mm hex. The tension adjustment requires a tiny little torx bit (whatever the size, it is the smallest one in my Harbor-Freight set). They could have easily just used another 2mm hex for that. Oh, I'm sorry...that would have been
sensible!
The cleat design seems to be designed to trap dirt and rocks rather than to shed them. The adjustment screws to control 'float' are part of the cleat. The cleat actually rotates in the shoe to provide 'float', so you set the screws as 'stops' (one for left rotation, the other for right). Unless you set them for "no-float", there is a gap between the screws and the fixed portion of the cleat. Gaps fill with whatever you're walking on, dirt, muck, etc. I can see where any 'float' might simply go away if you got a pebble or something lodged in there. Sorry for the giant pic of my shoe...
You can see the set-screws on the left hand side of the cleat.
You may also see that they're pretty scuffed up after just a few months of riding/walking. They aren't very deeply recessed in these shoes. They walk fine...but they also "crunch" on anything but dead-flat, super smooth concrete.
Otherwise, I have found them to do the job. They don't unclip unexpectedly and they're fairly easy to adjust. They solved my problem...but I'm simply not sure I like them. I will be buying yet another set of SPDs sometime in the future...I won't be happy until I can compare the two systems.