I have a Specialized Hard Rock Comp mtn bike with the factory Suntour cranks. I'm 6'1 and have the seat height set so that my legs are dead straight and pretty much locked with my heel on the pedal at the six O'clock position. I have SPD pedals so my knee has a slight bend when I'm actually riding it.
I'm finding that on the up stroke my leg appears to come up to high, and is rather fatigueing. If I set the seat even higher to try and avoid this, then my hips start rocking on the seat. This is the first bike I've ever noticed this on. It's a 21" frame so it's obviously for taller people. You'd think the cranks would be shorter. Is this a normal occurence?