While this is truly a fun idea to contemplate, and I am all in favor of human-powered craft (I have a Surfbike), I believe that there is way too much resistance in traveling through snow to make this practical. It might be OK in packed-down snow, but any sort of depth is going to kill ya after about about 100 yards. And you can forget about getting out of first gear unless you're going downhill! That's probably why you never see any. But keep thinking! I love inventions.
