The invention provides a propulsion, braking and anti-rollback control assembly for use in manually propelled vehicles such as wheelchairs. In one embodiment, the invention provides a wheelchair with a control lever assembly and related force conveyance connecter that propel, brake and steer the wheelchair in a mechanically advantageous way while minimizing rollback. A seat-activated auxiliary braking system is also provided. Additionally, the invention provides a selective anti-rollback disengagement system that facilitates selective rollback.