- Familiarity: I've put it through the wringer
Okay Shimano makes a solid pedal, and these will definitely get you through a few seasons. If you have knee problems these may not be a super choice. SPD pedals have about a 5 degree float meaning you can move your foot in the pedals about 5 degrees either way. In other words, you are LOCKED into these things.
Other pedals (ATACS) have a 20+ degree float so you can move your foot around a bit more and give your knees/ankles a bit or wiggle room.