Pendulum Pedals
Overview
September 2022 - December 2022
CAD • Human-centered Design • 3D Printing
The Pendulum Pedals is a gravity powered self-balancing bicycle pedal that I designed as part of my class Design Thinking & Communication I. In this class I worked with 3 other team members to create a system that would help Ms. Redmond, a stroke survivor, regain the ability to ride her bike. Our group created the system: the EZ Bike that used the Pendulum Pedals that I designed as well as some stabilizer wheels to help her maintain balance and ride her bike again. This page will only focus on the design of the Pendulum Pedals.
Design
Our client struggled with controlling one leg, due to her stroke. As such, it was difficult for her to pull her leg onto the pedal and start pedaling. The Pendulum Pedals, intended to replace the standard pedals already present on the bicycle, are equipped with two major modifications from standard pedals to address the client’s difficulty of easily getting her left foot onto and properly placed on the pedal: they have a larger size and an elevated axis of rotation.
The first major modification in the Pendulum Pedals is the increased size. At 4 inches by 3 inches, they are substantially larger than standard pedals, which makes it easier for the client to place her foot on the pedals using only the sense of touch—something we observed she had trouble doing during the user observation. The increase in size decreases the likelihood of the user fumbling or missing the pedal with their foot, allowing her to start pedaling and come up to speed faster, thus reducing the risk of losing balance.
The second major modification in the Pendulum Pedals is the elevated axis of rotation. Whereas standard pedals rotate about an axis of rotation that passes through the center of the pedal itself, the Pendulum Pedals include extension arms that attach to the crankset (i.e. the arm driving the gears) at an offset axis of rotation above the actual body of the pedal. Therefore, instead of themselves rotating about the axis, the Pendulum Pedals “hang” from the attachment point via their extension arms, hence the name of the design. The body of the pedal is always perpendicular to the extension arms; these do not rotate with respect to each other.
This change in axis of rotation addresses the client’s problem in two ways. First, because the attachment point is higher relative to the body of the pedal, the body of the pedal itself will be lower relative to the bicycle. This means that the client does not need to raise her foot as high a distance in order to put it on the pedal and start pedaling which, based on the observation, was a point of struggle for her. Second, because the Pendulum Pedals “hang” from the attachment point, their natural rest position is at the lowest possible point, where the pedals are level. This mitigates the situation where the pedals are tilted at an angle other than horizontal, which makes it difficult for the client to place her foot on the pedal.