A ratcheting strap-down system for use with a crossbar to securely transport any variety of objects. The ratcheting strap-down assembly includes a ratcheting receiver and a cam clamp receiver. The ratcheting receiver includes a ratcheting assembly and a locking mechanism and is adapted to engage a second end of a flexible strap. The flexible strap is preferably made from reinforced steel cog belt, making the system and the objects it's securing less susceptible to theft. The ratcheting strap-down system is particularly useful for securing one or more surfboards to the crossbars of an after-market roof rack assembly.