Master's Thesis
Master's Thesis
Embedded Files
2024-2025
Abstract
Abstract
The design of full-suspension mountain bikes is a careful balance of suspension kinematics, structural dynamics, and manufacturing optimization for the expected use case. A bike designed to excel in one area will likely exhibit reduced performance in others. This optimization problem is addressed by designing, integrating, and testing a dual-rate spring system within a fully custom frame. The dual-rate spring is fully decoupled from the rest of the suspension kinematics, providing designers with an additional parameter to achieve ideal suspension behavior. This is accomplished by placing a thermoplastic polyurethane (TPU) bushing in series with the rear shock. The influence of this bushing is limited to the first 30% of suspension travel by use of bump stops. The design and manufacturing of the test platform are covered. The viscoelastic behavior of the TPU bushing is analyzed and its effects on the vibratory response of the theoretical system is studied. Testing methodology is covered, and frequency analysis is used to determine the efficacy of the design.
Completed Frame
Completed Frame
Result of 120+ hours of manufacturing time.
Custom Front Triangle Fixture
Custom Front Triangle Fixture
Tooling plate and inserts were machined on a manual mill and lathe respectively. The fixture located the main pivot, rocker pivot, and shock mount relative to the bottom bracket.
Whole Frame Fixture
Whole Frame Fixture
Anvil frame jig held the frame in-place so the rear triangle could be welded in. Frame welded at sag to minimize bending in the flex stays.
Completed Front Triangle
Completed Front Triangle
316L 3D Printed Components
316L 3D Printed Components
Yoke, dropouts, main pivot, and seatstay pivot were all custom designed and welded into the frame with er312 filler rod.
7075-T651 Rocker
7075-T651 Rocker
Symmetric four piece rocker translates loads from the rear axle into the shock.
6061 Shock Mount
6061 Shock Mount
Shock mount and bump-stops were machined out of 6061 on a manual mill.
Headtube Badge
Headtube Badge
Stainless steel logo silver brazed onto the headtube.
Rocker Pivots Welds
Rocker Pivots Welds
PETG Softjaws
PETG Softjaws
All 316L 3D printed components required softjaws for machining on a manual mill to correct distortion from printing.
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