I just returned Saturday from a 8 day ride on the trail with 9 bikes. The smallest bike was a 250, not big enough! My son and I rode 650l's which were almost too heavy, but most of the bikes were 600's. We even had a BMW Dakar which was a handful and way too heavy for this trail. We did over 1000 miles of dirt with Sam from Green River Utah to Battle Mountain, NV and then on to Oregon where we left the trail and rode pavement back home to northern CA. 1500 miles overall. Lots of trail, sand and dirt roads. If you get a chance try it. You must navigate by his maps and they are not easy to follow sometimes, we got lost a couple of times with Sam leading.