This adaptor bar adds a top tube to your bicycle frame so that it can be installed properly on a bicycle carrier. It's designed to be used with hard-to-mount bike frames, such as full-suspension bikes, women's bikes, or other non-conventional designs. The bar features an internal spring that maintains constant tension to keep your bike secure. The product is designed to fit bikes that have a distance of 16 inches to 27 inches between the seat post and the stem, and installation is easy. Plastic-coated hooks are there to protect the finish of your bike.