Front-wheel friction drive electric bicycle motor Chen, Oliver; Ghoussoub, Mireille; Zhou, Cherry
Many cyclists are seeking easy solutions to bring electric power to their bikes. Having an electric motor that can be switched on to get a boost going uphill, to go faster, or to simply take a break from pedaling can be very useful. With these motivations, we sought to develop a front-wheel friction-drive motor system that could be easily mounted and removed from any adult-sized road bike. The objective was to develop an easily mountable solution containing the motor, controller, battery pack, and throttle that could be installed within minutes. Friction-drive motors are a cheaper, lighter alternative to the more common hub motors that must be permanently attached to the wheel of the bike. Indeed, the motor mechanism component of our design weighs 1.45 kg, and the total weight of our design does not exceed 3 kg (depending on the size of battery pack used). The design of our solution was based on goal of keeping the installation as simple as possible, whilst ensuring that the mechanism could tolerate the strong rotational forces introduced by the motor. Our solution mounts at the handlebars by means of two snap-on clamps, as well as at the fender holes, located at the hub of the front wheel of the bicycle. The design can be adjusted at two locations: by changing the angle between a horizontal and a vertical cantilever, as well as by changing the height of the supporting rods. The motor is attached to a pivot point, such that is has sufficient room to engage and disengage with the front tire. Blocker pieces are located strategically to ensure that the motor does not swing too far back and get stuck in the wheel. The mechanical aspect of our solution has proven to be successful. We were able to mount the mechanism to five different bicycles, all of which varied greatly in handlebar shape and tire size. In all these cases, our solution was easily installed in under two minutes. Installing a user-friendly throttle proved to be very challenging. The most successful attempt entailed running the controller by means of a purchased servo tester circuit; however, our throttle setup was not functioning in time for us to do test ride our solution. We therefore cannot present meaningful results as the electrical efficiency of our system. We recommend three important actions to be taken to ensure that our solution be safe and fully-functional. First, all electrical parts should be protected in a water-proofed enclosure. Secondly, a push button throttle should be installed along with the servo tester circuit. Finally, we recommend that an emergency brake be installed to ensure the safety of the user in the case where the throttle or controller fails.
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