I took my mountain bike out today for the first time in two years. I took it to a trail that's all single track but relatively mild. I obviously didn't try hard enough because I'm not bleeding but I rode some sections that I felt were "iffy" and walked some sections that I probably should have ridden. Somewhere along the way I jammed up my front shifter and couldn't shift out of the big ring. The big ring is pretty much useless to me on singletrack so I walked back to my truck.
Here's my question: What percentage of time do you actually have to be riding the bike to still call it mountain biking rather than something else?