Juha

I would be very careful doing it. Obviously it's doable, re: the guys you mentioned.

I do a fair bit of XC skiing, and using snowmobile/dog/reindeer sled tracks is considered a no-no there. Especially if they're marked tracks close to ski resorts or other habitats. Someone's bound to come blasting along at some point, and snow dampens sounds very well. I'd imagine you'd have time to move over (IF it's a snowmobile), but not enough for a planned exit at a well chosen spot. If you just blindly jump off the track, you'll end up in waist deep powder even with normal XC skis, nevermind a bike. That may or may not be fun. Plus you'll only get barely out of track that way, and getting back is going to be hard work at best.

If you're way out in wilderness, sure, anything goes. Anywhere else with more traffic, be careful.

--J