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Sturmey S2 2--speed[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
1 24 18 18[2] 60 1 0.714    5/7   
2 24 18 18 60 2 1.000 1        1.400
[1]
John Allen:
Theoretical but probably correct, given that Sturmey-Archer uses a 60-tooth ring gear for most hubs.
[2]
John Allen:
Note calculation by formula. Number of teeth of planet gears is immaterial to the ratios.