Course: Engineering Design II | Carnegie Mellon University
Project Team: Ryan Chang | Rachel Chow | Jeremy Jiang | Melissa Mann | Alex Muñoz
OBJECTIVE:
To redesign a current product on the market.
CURRENT PRODUCT ANALYSIS:
Our team chose to redesign the bike lock because bike theft is a big issue, especially on college campuses. To start the project, we took apart and studied two bike locks for their strengths and weaknesses. During the disassembly, we also analyzed the bike locks in terms of failure modes and design for manufacturing, assembly, and the environment.
USER & MARKET RESEARCH:
Having studied the current common bike locks on the market, we looked into more unique bike locks and expanded our market to bike accessories, such as lights and baskets. We also conducted user research through interviews, surveys, and observations to determine the needs of the user. We talked to a variety of stakeholders including specialty bike and repair shops, locksmiths, CMU's Cycling Team, retail stores, and CMU police officers. From what we were told and what we saw, there were two big concerns. The first was that cyclists wanted a lightweight, easily carried lock that was still very secure. The problem was that lightweight and easily carried locks tended to be less secure, and more secure locks needed to be bulkier and a little more unwieldy, especially while riding a bike. The second was that bike accessories are constantly stolen, especially lights.
CONCEPTUAL DESIGN & MECHANICAL ANALYSIS:
As such, for our product, we aimed to solve these two problems. Our idea was to combine a U-lock with bike lights. This way when you lock up your bike, you are also locking up your lights, and when you are riding your bike, you have your lock mounted as your lights. Combining these two bike accessories forced us to strike a balance between many attributes of the product. The mounting brackets for the lights had to now be designed to support larger and heavier lights, and this made us aim to make the overall product smaller and lighter, but we had to also make sure that the lock was still as secure as a regular U-lock. Throughout our concept iteration, we also performed a variety of mechanical analyses on the product from determining the required clamping force needed to keep the lights stable while riding to analyzing the stress placed on the mounting brackets when they are supporting the lights.
PROTOTYPING & FINAL DEMO:
We went through a couple of iterations for our prototype, and for our final working demo, our prototype was constructed out of 3D printed ABS plastic, laser cut acrylic, and machined aluminum. The back light for the bike was housed in the U-section of the lock, and the front light was housed in the cylindrical shackle. The final working demo also included a working lock made from acrylic that used an Allen wrench as a key.