Valygrl has summed it up about right. the best roadsfor cycling in Yellowstone are on the west side of the park. From West Yellowstone down to Old Faithful and then on arround to the Zsouth entrance at Grand Teton. The rest of the roads are mostly narrow and heavily trafficed by inexpereinced RV drivers. Its really pretty dangerous for cycling. Depending on where you are, the bison are a problem as they will just get into the road, and its your job to miss and not annoy them. They are scary big. Stores are few and far between, carry food with you.