Final Design Report for Human Powered Vehicle Drivetrain Project Sponsored by The Cal Poly Human Powered Vehicle Club in conjunction with George Leone May 31, 2019 Team members: Derek Fromm: [email protected] Luke Opitz: [email protected] Michael Juri: [email protected] Olivier Côté: [email protected] i Statement of Disclaimer Since this project is a result of a class assignment, it has been graded and accepted as fulfillment of the course requirements. Acceptance does not imply technical accuracy or reliability. Any use of information in this report is done at the risk of the user. These risks may include catastrophic failure of the device or infringement of patent or copyright laws. California Polytechnic State University at San Luis Obispo and its staff cannot be held liable for any use or misuse of the project. ii Abstract The Cal Poly Human Powered Vehicle Club is building a bike to surpass 61.3 mph in 2019. The club and their mentor, George Leone, have proposed a senior project to design, build, and test the drivetrain for this year’s human powered vehicle. Research into human powered vehicles and their drivetrains has shown that the power that a rider can output and the efficiency at which the rider can pedal depend extensively on the design of the drivetrain. Despite the existence of standard bicycle drivetrain designs, the senior project team has found that the best design to meet the club’s requirements is a completely custom drivetrain based on the rider’s dimensions and preferences. The team defined a list of technical specifications that they used to validate the completed final prototype. The final confirmation prototype functioned as intended and all the specifications were met with the exception of total cost. Details of the team’s design, manufacturing, and testing processes are outlined in this document. iii Table of Contents 1. Introduction ............................................................................................................................................... 1 2. Background Research ................................................................................................................................ 1 2.1. Product Research .............................................................................................................................. 1 2.1.1. French Team .............................................................................................................................. 1 2.1.2. Italian Team ............................................................................................................................... 2 2.1.3. Dutch Team ............................................................................................................................... 2 2.1.4. Canadian Team .......................................................................................................................... 3 2.1.5. Hans Van Vugt .......................................................................................................................... 3 2.2. Customer/Needs Research .............................................................................................................. 4 2.3. Technical Research............................................................................................................................ 5 2.3.1. Rider Power ............................................................................................................................... 5 2.3.2. Rider Pedaling Efficiency......................................................................................................... 5 2.3.3. Pedals, Cranks, and the Chainring .......................................................................................... 6 2.3.4. Shifting........................................................................................................................................ 7 2.4. Relevant Patent Research ................................................................................................................. 8 3. Objectives ................................................................................................................................................. 10 3.1. Problem Statement .......................................................................................................................... 10 3.2. Project Boundary Diagram ............................................................................................................ 10 3.3. QFD House of Quality .................................................................................................................. 11 3.3.1. Discussion of Specifications .................................................................................................. 12 4. Concept Design ....................................................................................................................................... 13 4.1. Ideation ............................................................................................................................................. 13 4.2. Functional Comparison .................................................................................................................. 13 4.3. Concept Analysis ............................................................................................................................. 14 4.3.1. Rear Wheel Drive, 2 Stage, Split-Offset .............................................................................. 14 4.3.2. Front Wheel Drive, 2 Stage, Split-Offset ............................................................................ 14 4.3.3. Front Wheel Drive, 2-Stage, Right-Offset .......................................................................... 15 4.3.4. Front-Wheel Drive, 2-Stage, Left-Offset ............................................................................ 16 4.3.5. Front Wheel Drive, 2-Stage, No Offset .............................................................................. 16 4.4. Concept Selection ............................................................................................................................ 17 4.4.1. Decision Matrix ....................................................................................................................... 17 4.4.2. Concept Prototype .................................................................................................................. 17 4.4.3. Design Considerations ........................................................................................................... 18 4.4.4. Preliminary Analysis Gear Selection .................................................................................... 19 iv 4.4.5. Concept Design Description ................................................................................................. 20 4.5. Discussion of the current risks, challenges, and unknowns ...................................................... 21 5. Final Design.............................................................................................................................................. 23 5.1. Design Description ......................................................................................................................... 23 5.1.1. Front System ............................................................................................................................ 24 5.1.2. Mid-drive system ..................................................................................................................... 25 5.1.3. Hub Subsystem ....................................................................................................................... 27 5.1.4. Shifting Subsystem .................................................................................................................. 29 5.2. System Function .............................................................................................................................. 29 5.3. Detailed Analysis ............................................................................................................................. 30 5.3.1. Gear Reduction Analysis ........................................................................................................ 30 5.3.2. Chain Load Analysis ............................................................................................................... 30 5.3.3. Structural Analysis .................................................................................................................. 31 5.3.4. Torque Steer Analysis ............................................................................................................. 32 5.3.5. Chain Path Analysis ................................................................................................................ 33 5.4. Safety, Maintenance, and Repair ................................................................................................... 35 5.5. Cost Analysis .................................................................................................................................... 35 6. Manufacturing .......................................................................................................................................... 36 6.1. Procurement ..................................................................................................................................... 36 6.2. Component Manufacturing ..........................................................................................................