Commute home yesterday was a B****

Was on my Steel MTB, and had PAIN oh yeah, nothing like it ever before had i Had! Was worse than after a metric century on the road bike, and my commute is only like 8km! From my butt, through the quads, the back of the knees, and my shins were all screaming. Not the first time I've had pain......only since ive started using the road bike for commuting some days. I just cant handle the pain on the MTB now! OWWW!!

BJE