Abstract: A conversion bicycle apparatus includes a chassis. The chassis includes a main tube. The chassis additionally includes a head tube. The chassis additionally includes a seat tube. The chassis additionally includes a rear fork. The rear fork includes a first fork arm and a second fork arm. The chassis additionally includes an attachment receiver. The attachment receiver is located proximate to a junction of at least the main tube and the rear fork. An attachment assembly is reversibly couplable to the attachment receiver via one or more protrusions and one or more corresponding apertures. The attachment assembly is additionally reversibly couplable to the attachment receiver via one or more fasteners.