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| Sturmey Brompton Special[1] | |||||||||||
| Number of gear teeth | |||||||||||
| Gear | Sun Gear 1 | Pinion to Sun 1 | Pinion to Ring 1 | Ring gear 1 | Path, 1=R to P, 2=Direct, 3=P to R | Gear Drive Ratio | Drive ratio as fraction | Ratio incre- ment | Ratio w/ 16T/13T | Ratio w/ 16T/13T | Ratio incre-ment |
| 1 | 34 | 12 | 12 | 60 | 1 | 0.638 | 30/47 | 30/47 | 0.638 | ||
| 1 | 34 | 12 | 12 | 60 | 1 | 0.638 | 30/47 | 480/611 | 0.786 | 1.231 | |
| 2 | 34 | 12 | 12 | 60 | 2 | 1.000 | 1 | 1.567 | 1 | 1.000 | 1.273 |
| 2 | 34 | 12 | 12 | 60 | 2 | 1.000 | 1 | 1.567 | 1 3/13 | 1.231 | 1.231 |
| 3 | 34 | 12 | 12 | 60 | 3 | 1.567 | 1 17/30 | 1.567 | 1 17/30 | 1.567 | 1.273 |
| 3 | 34 | 12 | 12 | 60 | 3 | 1.567 | 1 17/30 | 1.567 | 1 181/195 | 1.928 | 1.231 |