Here is a clip demonstrating poor pelvic stabilityWhen we sit on a bike, pelvic stability on seat is all important. All important because your pelvis is the foundation of your position. Your legs reach down from and your torso extends out from your pelvis. Any asymmetries or instability of pelvis on seat flows out to the periphery a whole raft of potential problems. Pelvic instability on a bike is both the most common root cause problem and the toughest to solve on the bike. . . I thought I had seen everything. Have a look at this clip. This gent has the greatest amount of pelvic movement I've ever seen on a bike. He wasn't aware of it but doesn't feel any pain either. I'm amazed! Click here to view it.