Upgrading the Perfect Urban Bike: Disc Brake Mounts for an Elevated Chainstay Frame

As an avid cyclist and bike mechanic, I’ve always aimed for the "perfect" city bike. After finding a used 90's MTB frame with an elevated chainstay, I set out to make it as low-maintenance as possible by upgrading it to accommodate disc brakes.

This project involved designing and fabricating custom IS160-standard disc brake mounts. I started by modeling a jig to ensure precise alignment of the mounts, then explored multiple iterations for the mount design. Early prototypes were crafted from cardboard (quick and dirty), followed by laser-cut models from Capa board, and finally functional prototypes 3D-printed in plastic. The 3D-printed versions allowed me to test the mounts by hot-gluing them onto the frame and attaching the brakes directly, following a “fail fast” methodology.

Once the design was validated both functionally and aesthetically, I waterjet-cut the final mounts from metal and welded them onto the frame. To handle the added stresses from the disc brakes, I reinforced the frame with a stiffening tube at the rear where forces are highest. For the front fork, I designed the mount to distribute braking forces along the fork’s length, ensuring durability and safety.

This project demonstrates my expertise in iterative design, prototyping, and fabrication, with an eye for both functionality and form in custom bike builds.