Also sometimes known as a sleeping hub, the Park Tool DH-1 Dummy Hub slides into the rear dropouts of a bicycle frame and replaces the rear wheel, keeping the chain in place while the wheel is removed for cleaning, service, or transportation. The DH-1 is compatible with all multi-speed and 1/8" chain, and can be used on frames featuring open dropouts or 12mm thru axles. The unique design allows the bicycle to be pedaled and the derailleur to be shifted, making the DH-1 an essential tool for chain cleaning or diagnosis of some derailleur issues.