Collisions with motor vehicles were an infrequent cause of injury for children riding in bicycle-mounted child seats, accounting for 4 of 43 cases in our series. 1 Bicycle-towed trailers have a low center of gravity and are very stable. The 2-wheel axle is perpendicular to the axle of the bicycle, which helps to prevent tipping. Many are designed with an attachment mechanism that prevents tipping, even if the bicycle is laid on the ground. Thus, the stability of the trailer is independent of the stability of the bicycle.
Trailers contain a seat belt for restraining the occupant.
Most trailers place their occupants less than 30 cm from the ground, limiting the height of falls from the trailer. Falls can occur if the child is not restrained or if an impact is sufficient to overcome the restraint. In one case the trailer tipped over when the bicycle and trailer hit a bump. The mechanisms of fall injuries associated with bicycle-mounted child seats include falls from the seat, falls resulting from the bicycle tipping over, and falls resulting from the seat becoming detached from the bicycle. Most bicycle-mounted child seats are more than 0.6 m above the ground.