I use Speedplay X1s on the road bike, CB Candy pedals on the commuters and XTR SPD pedals on the MTBs. I like them all, but for different reasons.
For my all day rides, wearing stiff carbon soled shoes, the Speedplay X pedals with the wonderful float really save my knees. My legs/knees can float in the position they want to be in without resistance and it is easy to snap out of them. At the end of the day my knees feel great.
For the commuter, I use commuting shoes and appreciate the walk-ability of the Crankbrothers cleats and the pedal platform that I can use without clipping in, like when coasting to a light. The distance I commute is short and the float is OK and keeps the knees happy.
For MTB riding, nothing beats the durability of Shimano SPD pedals. I've bashed them into rocks, gotten them muddy and super dirty, and they keep working. My oldest pair is probably 12~13 years old and going strong. They are a bit heavy for commuting and lack the platform the Crank Bros Candy pedals have, and lack the float and light weight of the Speedplay, but they are my first choice for mountainbiking.
If I wanted walk-ability on the road bike and the extreme float was not paramount, I would use SPD pedals, as the Shimano pedals are bomb proof durable and worth the weight penalty over the CB pedals.
For the beginner, there are many here who would say Speedplay Frogs. While I have not tried them, (one day), they look easy to get in and out of, have lots of float, and a walk-able cleat. They actually sound like a good choice for road bike use with a shoe you can walk in.
Tzvia- rollin' slow...
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