Quote Originally Posted by Grog
Stretching cold muscles is supposed to be a bad idea.

Spinning your legs will be a good warmup, use an easy gear. You can always stretch during a break, but afterwards will bring the most rewards.

I wish I could explain why, but I can't. My coaches have always insisted on that though...
Ditto.

There are studies that have shown that stretching actually decreases total strength output. The studies were weight-lifting based, but I would think a similar theory would apply here. You absolutely do need to warm up...easy spinning to get the blood flowing to the muscles in your legs AND in your heart. And stretching at rests is probably helpful...especially if the rest ends up being longer than anticipated (like wating in line for a toilet!). Stretching afterward is VERY important...cool down with easy spinning again, get the HR back to normal, and then stretch the muscles slowly.