J.A. Jackson (v. 2.35)
contents
overview
This is the second iteration of a bicycle I made in 2023, improving upon a number of issues logged over the course of the last year, and allowing the frame from the previous project to be reused in another (future) bicycle build.
It is a titanium-framed road/touring cycle with an internally geared rear hub of eight speeds. It has a number of features atypical on road/touring cycles, such as horizontal dropouts, both disc and rim brake mount points, threads for all manner of fenders, racks, and accessories, and clearance for wider wheels.
The name comes from a Joycean description of a Trinity College bike race:
“Bang of the lastlap bell spurred the halfmile wheelmen to their sprint. J. A. Jackson, W. E. Wylie, A. Munro and H. T. Gahan, their stretched necks wagging, negotiated the curve by the College library.”
specifications
parts
(coming soon)
gearing
The Alfine 8 hub is attached to a 21t rear sprocket, and the chainring on the crank is 43t. This results in the following eight gears, in gear-inches and MPH at 80 RPM cadence:
| Gear Inches | Incremental Change |
|---|---|
| 29.1 | |
| 35.6 | 18.26% |
| 41.4 | 14.01% |
| 47 | 11.91% |
| 55.3 | 15.01% |
| 67.6 | 18.20% |
| 78.5 | 13.89% |
| 89.4 | 12.19% |
| Gear | MPH @ 80RPM |
|---|---|
| 1 | 7.8 |
| 2 | 9.5 |
| 3 | 11.1 |
| 4 | 12.6 |
| 5 | 14.8 |
| 6 | 18.1 |
| 7 | 21 |
| 8 | 23.9 |
frame dimensions
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