CapStrap - A smarter way to safely tie down your motorcycle! The CapStrap tie-down system is designed for BMW motorcycles with an open axle swingarm. The CapStrap open axle tie-down system is designed for BMW motorcycles with 5.3cm hollow axles. The system ensures your motorcycle stays perpendicular and in place wherever you take it. This innovative tie-down system makes clever use of one of BMW’s technical features. Using the swingarm’s open axle construction, the CapStrap open axle tie-down system protects the bike’s suspension system from excessive tie-down pressure. The tie-down Strap is rigged through the middle of the axle, ensuring minimal obstruction from the bike’s exhaust-pipe and luggage bags.