Saris Bike Beam Top Tube AdapterBy creating a virtual top tube for specialty frames, the Bike Beam lets you bring any bike along for the ride. Amazon. com If you have a non traditional bike frame such as a full suspension or a women's bike with slanting frame the Saris Bike Beam will help you transport the bike using your trunk or hitch mounted rack. It attaches from the seat post to the handlebar area of the bike to create a level beam that can be easily stored on a rack.