Hi I was just at my LBS over my look pedals and I asked about SDP and the looks. I was told the looks don't have as much float to them as the spd to. If you have knee problem spd are better because of the float like your on water. I would take them in to your LBS and see how you are spinning with them You could be heel in and not notice it your self someone would need to be infront of you to see it. Try that