Position, position, position.
Two days ago, it was windy, I went to this group ride, we had firmed a good paceline from the beginning of the ride all the way to the end, I got 19.5 mph avg. for 48 miles. I have never go this fast for this distance, and yesterday my legs didn't feel a thing, no pain or nothing. I am more a runner than a cyclist, and I always think my legs are too heavy for spinning, the lesson I learned from this ride is position.
Stay with the paceline position, don't let the gap open. DON'T!
Hold a relaxing position, don't waste too much energy on your upper body, focus on your padding.
Most important position is a good bike fitting position, needs to find yourself a right bike.
After all, practice, practice, practice, with a group that is faster than your PR.
Did I miss anything else? I will get back to you. Learning is a life time bussiness.http://forums.teamestrogen.com/images/smilies/wink.gif