MODULAR HUB SPACER (MHS)
Modular, Reliable, and Economic
Pictured: Old Frame Jig
Problem with old designs:
Dropouts warped while welding and spacing was not maintained in previous jig → Rear wheel did not fit. Spacing was not modular and was specific to the old frame's geometry.
Objectives:
- Spacer will maintain correct spacing during welding
- Spacer can be reused for future projects
- Cheap to manufacture
- Integrates into new jig and mounts to sliding 80/20 rails
Inspiration
DT Swiss hubs (center of the wheel) incorporate a modular "endcap" system to enable a wide range of fit.
I can utilize this design concept of swappable parts to attain various spacing standards.
CAD for 135mm x 5mm Quick Release Spacing
Central "base" will maintain a constant 100mm spacing with a 20mm internal diameter to fit "endcaps".
Endcaps will adjust the shaft diameter and horizontal distance to fit the desired spacing standard.
CAD for 142mm x 12mm Thru Axle Spacing
Endcaps here are 3.5mm longer than the Quick Release endcaps to account for 142mm spacing.
Internal diameter of endcap increases from 5mm -> 12mm to accommodate larger axle.
MANUFACTURING AND IMPLEMENTATION
Center base manufactured via 3D printing for reduced cost and increased manufacturing speed.
Base is far enough away from welding sites to neglect welding heat and subsequent melting of PLA plastic.
Endcaps manufactured via lathe & turned to correct dimensions.
Dropouts held in place by a single quick release skewer (pictured).
MHS integrated into jig design with 80/20 rails.
Rotation of dropouts constrained by length of seat stays and chain stays.
Fore/aft translation constrained by distance from bottom bracket.
Up/down translation constrained by bottom bracket drop dimension in CAD.
MHS & Frame Jig all ready to be welded!
SUCCESS!
The Bike Builders of Berkeley (BBB) Gravel Bike was a success, thanks to MHS! Spacing was maintained during welding and all rear wheel components fit as they should.
