Umm, I use my Nexus One while hiking all the time. I lose cell & data reception, but if I've already got Maps or Navigation open when I lose reception, it'll keep the map on screen.
Problem is your nexus one isn't ruggedized and has poor battery life in comparison, not to mention you can't swap out the batteries. For sure it works, but it's like commuting in a truck or taking a honda civic filled with tools to a construction site. Both of them work, but it's not the best tool for the job.
Also, if you have a large bike route, 50 miles or so, you have to cache a huge amount of tiles to see that route at any detail. Currently, Google Maps fails at consistently doing this even with expanded cache sizes.
