Please take this with a little skepticism since I haven't used a trailer a lot but, when I did try them, I didn't care for the two wheel design because often when riding on a narrow single track like on a path or even near the edge of the road, the wheels of the trailer would occasionally get into things that I was trying to avoid with my bike wheels since they didn't track in the same line. I also liked the one wheel Bobs better when heading downhill as it seemed again like it tracked better and didn't affect my steering as much. YMMV