I also did this ride in '05 with a friend and enjoyed it, despite being rained on the last fifteen miles back to West Yellowstone. Firehole Hill, the one out of Morris Junction is a pretty good one. What the bummer is, is there are usually elk in the meadow on the left side of the road, a perfect place for pics! Stopping though, means one loses momentum to grind up the hill! Another thing to think about is that the ride starts at an elevation of 6200 feet. I don't think the elevation should be a problem though, at least it didn't bother us. I am signing up for this ride again, as the scenery is hard to beat and the park is pretty well empty by that time of year making cycling a joy.