I ride the majority of my rides on the trails but catch an ocasional ride on my old road bike. Ten years ago I was riding 90% road and I still have the same bike with the same ride position. I find that on the trails my quads and knees feel the pain by the end of the day where as on the road, my hamstrings and glutes take the beating. I had a several year hiatis between these activites, but i generaly run a higher cadenence on both bikes (about 90 rpm). Is this a difference in body position or ride type. I can tell my pedal stroke is not as smooth as it used to be in the roadie days.