The BikeSmart BarNone Frame Adapter is an ingenious solution for carrying bicycles that don't have standard top tubes on rear-mounted car racks. The heavy-duty, spring-loaded clamps attach to the bike at the stem and seatpost, creating an effectively straight top tube to suspend from the car rack. The frame adapter works with most step-through frames (low-step, mid-step) and kid's frames. Specs For use with racks where bikes are secured by the top tube, such as hanging style hitch racks, trunk racks or home bike storage solutions. Minimum seat tube to stem distance: 18" Maximum seat tube to stem distance: 28" Bike weight capacity: 35 lb