It seems to take me 6 miles to warm up no matter whether I'm on the road or dirt (totally illogical I know). I, too, have a short nasty hill almost right out the door which is then followed by a few miles of downhill which turns me into an ice cube. Warm-up is tough. But no matter the terrain, I find that the easier I take the first few miles or minutes (or 48 mins) the faster and stronger I can finish. I think this is just normal physiology. The time it takes to warm up is unique to each of us.

I know plenty of bike guides who generally advise their trip clients to use 1 min of warm-up for every year of age. This is may be a little conservative when you're on regular training rides when you have rest days, but for a week long trip it is very sound advice for the average rider.

So you have the choice of using a trainer first or just spending a few miles (or 6) spinning slow and easy.