Abstract: A device for towing a trolley includes a rigid shaft having a proximal end and a distal end. A user-releasable clamp is associated with the distal end and is dimensioned to grip a handle of the trolley. A user-releasable coupler is associated with the proximal end for coupling the device to a user. Both the clamp and the coupler being user-releasable provides great flexibility for use with a wide variety of trolleys and for ease of storage.

Abstract: A power transmission system for a wheeled personal transportation device such as a bicycle comprises a sequence of at least three operably interconnected sets of gearwheels, a first set in the sequence for receiving rotational force and a last set in the sequence for transmitting rotational force for a driven wheel of the device. The first set and the last set each comprise user-selectable gearwheels. At least one intermediate set in the sequence comprises an input gearwheel subset and an output gearwheel subset, at least one of the input gearwheel subset and the output gearwheel subset comprising a plurality of user-selectable gearwheels. A frame for a personal transportation device comprises a base and a steering shaft on the base for supporting a steering column. Crank connection means are provided on the base for operably receiving a crank/pedal combination and an associated first set of user-selectable gearwheels.