SportRack Universal Upright Roof Bike Carrier. So you've got the crossbar rack on your car already, and now all you need to round out your carrying capabilities is an awesome bike attachment. SportRack's Universal Roof Upright Carrier clamps right onto most OEM and aftermarket crossbars up to 3.5 in diameter, so with a simple, tool free attachment you can safely haul your beloved bike to the nearby trails or all the way across the country. This upright carrier features a locking cam adjustment so you can not only haul your bike, but secure it as well...and remember, upright means just that...you don't need to remove wheels or anything. Just secure and go!