mcavana,
A broom handle clamp is a clamp that you mount on a wall inside a broom closet. When you want to put the mop or broom away you just push it into the clamp (its spring loaded) and it grabs the broom (or mop) handle. This device can be found at most hardware stores. They are great for bike mounts as the broom handle is about the same dia. as a handle bar.