It doesn't matter what distance the ride is - its the events and the trail that make a ride epic. I've done 5 hour rides that were boring as hell, and 25 - 60 minute descents that tested every part of your bike and body and left you relieved to be back on flat ground. My first lap down Mount 7, runs in the pouring rain in Queenstown, even a dusktime run from Garbanzo for an Australian on his first trip to Canada. All not that significant distance wise, but certainly epic. My favourite "epic" ride last year - Top of the World into Ride don't Slide into Creekside pub for beers and burger before slugging a DH bike back along the highway to Whistler.