We tried cowboy trail from Valentine to Ainsworth but ended up on hwy.20 which had a wide shoulder(but some wide cracks) The surface of the trail was like limestone, but not finely crushed, like finer gravel. The trail also is known for many stickers. A mountain bike or equivalant would be the best on the section of trail we saw. Cowboy Trail is not finished going east of Valentine, as far as I know. Nebraska Highway Department should have information.