Up: Table of Contents
Sturmey-Archer FC[1]
  Number of gear teeth         Number of gear teeth            
Gear Sun Gear 1 Pinion to Sun 1 Pinion to Ring 1 Ring gear 1 1=R to P, P to S 2=Direct, 3=P to R   Gear Drive Ratio Stage 1 drive ratio as fraction Gear drive ratio modified Sun Gear  2 Pinion to Sun 2 Pinion to Ring 2 Ring gear 2 Path: 1=R to P, 2=Direct, 3=P to R Gear Drive Ratio Stage 2 drive ratio as fraction Total Drive Ratio Total drive ratio as fraction Ratio incre- ment
1 30 14 14 60 1 0.667    2/3    20 20 20 60 1 0.750    3/4  0.750    3/4   
2 30 14 14 60 1 0.667    2/3  -0.222 20 20 20 60 1 0.750    3/4  0.900    9/10 1.200
3 30 14 14 60 2 1.000 1          20 20 20 60 2 1.000 1        1.000 1        1.111
4 30 14 14 60 1 0.667    2/3  -0.167 20 20 20 60 3 1.333 1   1/3  1.091 1   1/11 1.091

[1]
John Allen:
Tooth counts verified:
https://hadland.files.wordpress.com/2012/07/1theory.pdf
https://hadland.files.wordpress.com/2012/07/2tables.pdf