Abstract: The present invention is a support wheel adjustment mechanism for a bicycle provided on either side of bicycle. Each support wheel mechanism includes a first element, a second element, a swivel hinge connection, an adjustable element and a fixing element. First element and second element are connected with each other by swivel hinge connection. Adjustable element has one end portion connected with hinge connection with first element and another end portion is selectively connected to any of adjustment openings such that support wheels are achieves desired elevation from ground. Adjustable element is secured in adjustment openings by use of fixing element.

Abstract: An unmotorized sand-rideable bicycle utilizes oversized balloon tires that have an enlarged footprint to permit the bicycle to ride up over even loose sand to provide ease of pedaling, as well as enhanced steering and stability over that associated with standard bicycles. A positive traction gear assembly may be employed to switch between single and dual rear wheel drive.