http://www.bikeforums.net/fifty-plus...g-warm-up.html

Yes, this topic was covered ~ 1 week ago. This thread has some good info for you.

57 here, I feel the same, takes me around the same 45min to 1 hour to warm-up before the muscles and cardio really feel efficient and ready to work. I believe this is why I struggle at times on my 1 hour commute back and forth from work.