Originally Posted by needmoreair

This seems like a pretty personal thing.

Personally, if I get in a proper pre-race ride either the day before or the morning before an afternoon race (meaning a 30+ min ride with a couple of jumps and efforts) then I won't usually bother with a warmup unless it's just to get in more miles for the day.

This weekend I did a race with another guy who warmed up on his trainer for about 35 mins and went straight from that on to the course. Same race, very different approaches.

You might want to experiment when you have the time to do so, if for no other reason than to see what you can get away with so when the situation arises (get lost or something) and you have to forgo the warm up you'll know if you're going to be golden or if you need to take it easy the first few miles to get your legs going.

I will add an exception. If I'm doing a good taper and have a lot of pop in my legs I might do a 20-30 min warmup with 4-5 mins of sustained efforts 'cause it seems like I always feel a lot more burn when I'm well rested then when I'm into a bit heavier training load.