2018
Mountain Bike Brakes
Cornell Baja
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During the Spring of 2018, I decided to work with another engineer on investigating the viability of using mountain bike brakes for the Baja vehicle. We believed that there was potential in using these parts in place of our current system or large off-the-shelf brembo calipers we had also used in the past. Plus, even if this was not viable, we may be able to learn from the systems.
The first step was to form a theoretical model. This could be broken down into three components: brake pedal force to master cylinder, master cylinder force to pressure, and use that pressure transmitted to the caliper clamping a rotor. These calculations were subsequently translated over to a spreadsheet calculator.
The next step was investigating potential options for the brakes. To our surprise, mountain-bike enthusiasts have compiled a significant amount of information online about the dimensions, weight, and performance of these systems. Many 3D models are also available online. So not only was it easy to plug numbers into our theoretical model and create a trade table to balance cost and performance, but it also meant that we could validate our model by comparing it to dynamometer torque data. We found that our model had a mere 8% error, which gave us confidence in using it.
Once we bound our selection to a few key candidate brakes, we created the CAD to package the parts into the wheel assemblies and redesigned the pedal bay to fit the mountain bike brake levers. Interestingly, since all hydraulic mountain bike brakes share a common mounting scheme, it was easy to create a solution that could accommodate multiple options.
In the end, we were able to procure the brakes and test them on one of our previous vehicles. They performed well, and we ended up using them during our 2018-2019 season. The year after, we reverted back to a custom system that we made lighter, and implemented many lessons from these parts including our bleeding process, seal selection, and more.