Suggested Citation:
Connors, Brendan and Mont Hubbard (2008)

Modelling and Stability Analysis of a Recumbent Bicycle with Oscillating Leg Masses

It has been observed in the testing of a recumbent bicycle with a very low centre of gravity that the pedalling cadence can affect the rider’s ability to control the vehicle. To understand the relationship between cadence and bicycle stability, a multibody dynamic model is created. This model has nine massive rigid bodies: the bicycle frame with fixed rider torso (with head & and arms), the front fork with handlebars, the front wheel, the rear wheel, the left thigh, the right thigh, the left shank with foot, the right shank with foot, and the cranks. Nonlinear equations of motion are compiled in Autolev, a symbolic calculator using Kane’s method for multibody dynamics (Autolev, 2005). A simulation of the bicycle slowly accelerating from its starting speed (5 m/s) to its target speed (35 m/s) is run iteratively over several gear ratios. A steering controller is implemented to stabilize the bike outside its stable stable speed range. The simulation displays the lean and steer angles as well as steering control torque. Lean angle and control torque increase significantly with cadence, and steer angle increases slightly with cadence. This relationship is used to create a shifting strategy to reduce the control effort needed by the pilot during top top-speed speed-record attempts.