ADJUSTABLE FREEWHEEL HUB ASSEMBLY

An adjustable freewheel hub assembly has a hub component, a coaster brake mechanism, and an adjusting switch. The hub component has an axle, a hub shell, a helix hub driver, and a sprocket. The helix hub driver has a pawl groove and a first engaging notch formed on its periphery. The sprocket is sheathed onto the helix hub driver, is hollow, and has a ratchet teeth construction formed on an inner wall of the sprocket and a second engaging notch. The coaster brake mechanism is disposed in the hub shell and is drivable by the helix hub driver. By the adjusting switch engaged in or detached from the first engaging notch and the second engaging notch, the freewheel hub assembly can be adjusted between a fixed-gear mode and a single-speed mode to have different functions.