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Decimal approximations of drive ratios of bicycle hub gears
Brand Speeds Model[1] Shifter position
-4 -3 -2 -1 (near) unity +1 +2 +3 +4
Ratio
Bendix 2-speeds Red Band, Yellow Band       0.682 1.000        
Blue Band         1.000 1.467      
3-speeds (See Sachs, SRAM)       0.734 1.000 1.362      
Rohloff Speedhub, 14-speed Each value in this row is the one directly below it, times the third-stage ratio of 0.409 0.279 0.316 0.360 0.409 0.464 0.528 0.599  
For these ratios, the third stage is locked at unity. 0.682 0.774 0.881 1.000 1.135 1.292 1.467  
Sachs, SRAM 2-speeds Doppel-torpedo       0.762 1.000        
Automatic, Duomatic         1.000 1.362      
Orbit       0.738 1.000        
3-speeds 25,29     0.600 0.750 1.000        
Universal Dreigang       0.800 1.000 1.250      
53       0.750 1.000 1.333      
55       0.750 1.000 1.333      
All 3-speeds 1970-, DualDrive       0.734 1.000 1.362      
4-speed Universal Torpedo     0.600 0.750 1.000 1.333      
5-speeds Sachs H 5100, 5113, 5120, 5213     0.667 0.778 1.000 1.286 1.500    
SRAM P5 5-speeds     0.633 0.781 1.000 1.281 1.579    
7-speeds Sachs Torpedo H 7203, -13, -20   0.593 0.677 0.815 1.000 1.227 1.476 1.685  
Sachs Super 7, SRAM S7, MH7205, -15, -25 0.574 0.677 0.809 1.000 1.236 1.476 1.742  
9-speed SRAM I-Motion 9[2] 0.542 0.621 0.727 0.853 1.000 1.172 1.375 1.611 1.846[3]
12-speed Sachs Elan 12-speed Speeds 1 through 6: 0.69 0.85 1.000[4] 1.18 1.33 1.49  
Speeds 7 through 12: 1.61 1.75 1.92 2.08 2.22 2.38  
Shimano 3-speeds 333, SG-3S21, G-3S23, F, G, 3SC, 3CC       0.750 1.000 1.333      
Nexus Inter 3       0.733 1.000 1.364      
4-speed Nexus Inter 4         1.000 1.244 1.500 1.843  
7-speeds Nexus 7-speed   0.632 0.741 0.843 0.989[5] 1.145 1.335 1.545  
8-speeds Nexus, Alfine 8-speed 0.527[6] 0.644[7] 0.748[8] 0.851[9] 1.000 1.223 1.419 1.615  
Sturmey-Archer (Also licensees and copies: Brampton, Hercules, NK, Schwinn-Approved, Sears, Styre, SunTour for the AW, BSA for the X.) 2-speeds S2       0.714 1.000        
  T,TB,TBC,TBF,TBFC,TF       0.750 1.000        
  TC close-ratio fixed/freewheel       0.865 1.000        
3-speeds Original 1902       0.800 1.000 1.250      
  A, C, F, FN, FX, N, S, V, X, BSA       0.762 1.000 1.313      
  AB, AB3, AG, AT, AT3, AW, AW3, AWC, C30, K, KB, KC, KT, KTC, QS-RC3, RD-RB3, RS-RF3, RS-RR3, RX-RD3, S30, S3B, S3C, SAB3, SBR, S-RB3, S-RC3, S-RF3, SX-RB3, SX-RK3, TCW, TS-RC3, TS-RF3, XL-RD3, X-RD3       0.750 1.000 1.333      
  AC       0.923 1.000 1.067      
  AF, ASC fixed     0.750 0.900 1.000        
  AM, AM Tandem       0.865 1.000 1.156      
  AR       0.932 1.000 1.072      
  KS       0.889 1.000 1.125      
  KSW       0.857 1.000 1.167      
  S3X     0.625 0.750 1.000        
  SW       0.722 1.000 1.385      
4-speeds FB, FG, FW     0.667 0.789 1.000 1.267      
  FC     0.750 0.900 1.000 1.091      
  FM     0.667 0.857 1.000 1.125      
5-speeds AB5, AT5, S5, S5/1, S5/2, S5C, 5-Speed Alloy, 5 Star, Sprinter 5, XRD5, XRF5      0.667 0.789 1.000 1.267 1.500    
S50(W), S5C(W), S5S(W), S-RC5(W), S-RF5(W), XL-RD5(W), X-RC5(W), X-RD5(W), X-RF5(W)     0.625 0.750 1.000 1.333 1.600    
7-speeds AT7, S7, S7C, Sprinter 7, X-RD7[10]   0.600 0.690 0.804 1.000 1.243 1.450 1.667  
8-speeds X-RD8, X-RF8, X-RK8, X-RR8[11] This hub only gears up.  Gears 1 through 4: 1.000 1.281 1.450 1.644  
Gears 5 through 8: 1.858 2.106 2.384 3.054  
S80(W), X-RD8(W), X-RF8(W), X-RK8(W) This hub only gears up.  Gears 1 through 4: 1.000[12] 1.30 1.48 1.69  
Gears 5 through 8: 1.92 2.20 2.50 3.25  
[1]
John Allen:
Lines in pink: need verification. Lines in blue: insufficient information or no information.
[2]
John Allen:
Reverse-engineered.
[3]
John Allen:
SRAM literature says 1.844 but calculation says 1.846.
[4]
John Allen:
This is unity ratio. Manufacturer only give other ratios to 2 decmial places.
[5]
John Allen:
Ratio is achieved by gearing down, then up.
[6]
John Allen:
These ratios are those of the top four speeds, times the first-stage ratio of 0.527
[7]
John Allen:
These ratios are those of the top four speeds, times the first-stage ratio of 0.527
[8]
John Allen:
These ratios are those of the top four speeds, times the first-stage ratio of 0.527
[9]
John Allen:
These ratios are those of the top four speeds, times the first-stage ratio of 0.527
[10]
John Allen:
Ratios are almost certainly correct, reverse engineered.
[11]
John Allen:
Ratios are derived from tooth counts in Sturmey-Archer technical information.
[12]
John Allen:
Manufacturer only gives ratios to two decimal places, but this is unity ratio.