I did this for kicks with my 4 month old. Total distance about 200ft. roundtrip @ < 10mph. Didn't work well on a road bike because of the way his body had to stay tilted due to my normal riding position, while my thighs kept colliding with his legs. Even if I was sitting bolt upright, my thighs would still collide with his legs. This idea, on a scale of 1 to 10, is a 0.