When I get on the mountain bike after a couple weeks off, I find myself a little less confident. I am more tentative on the loose turns and drop-offs. It takes me a good two hour ride to feel back in sync with the mountain bike. Then when I switch back to the road bike, I feel really stretched out, and it takes a little while to get used to that! However, I've only been a bi-bicyclist for about a year. Maybe over the years things even out?