A retractable top assembly for a vehicle, commonly referred to as a bimini top, includes a covering mounted on a pair of struts which are movable relative to one another to move the covering between a deployed position covering at least a portion of the vehicle and a retracted position. In the retracted position, the covering is wound upon a spindle rotatably mounted within a housing mounted on one of the struts. The housing has a slot through which the covering extends, so that the covering is attached to the other strut. A torsion spring within the housing biases the spindle in a direction winding the covering onto the spindle and thereby maintaining tautness of the covering as it unwinds from the spindle and is moved into the deployed position.