Modified Stock Gearing - Boston Gear

SPEED RATIOS - CENTER DISTANCES - CHAIN LENGTHS
Roller Chain Drives
Selection
Teeth
Driven
Teeth on Driver Sprocket
Sprocket 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
1.36 1.25 1.15 1.07 1.00
15 6.469 7.235 6.993 7.748 7.500
26 28 28 20 30
1.45 1.33 1.23 1.14 1.07 1.00
16 7.207 6.971 7.736 7.494 8.249 8.000
28 28 30 30 32 32
1.55 1.42 1.31 1.21 1.13 1.06 1.00
17 7.943 7.710 7.473 8.237 7.994 8.749 8.500
30 30 30 32 32 34 34
1.64 1.50 1.38 1.29 1.20 1.13 1.06 1.00
18 7.669 8.446 8.212 7.975 8.737 8.495 9.249 9.000
30 32 32 32 34 34 36 36
1.73 1.58 1.46 1.36 1.27 1.19 1.12 1.06 1.00
19 8.404 8.174 8.949 8.714 8.477 9.238 8.995 9.749 9.500
32 32 34 34 34 36 36 38 38
1.82 1.67 1.54 1.43 1.33 1.25 1.18 1.11 1.05 1.00
20 8.124 8.909 8.679 9.452 9.216 8.978 9.739 9.495 10.249 10.000
32 34 34 36 36 36 38 38 40 40
RATIO
CENTER DISTANCE - IN PITCHES
CHAIN LENGTH - IN PITCHES
To obtain corresponding values in
INCHES, multiply by the appropriate
Chain Pitch.
1.91 1.75 1.61 1.50 1.40 1.31 1.24 1.17 1.11 1.05 1.00
21 8.857 8.632 9.414 9.183 9.955 9.718 9.479 10.239 9.995 10.749 10.500
34 34 36 36 38 38 38 40 40 42 42
2.00 1.83 1.69 1.57 1.47 1.37 1.29 1.22 1.16 1.10 1.05 1.00
22 9.590 9.365 9.139 9.918 9.686 10.457 10.220 9.980 10.740 10.496 11.249 11.000
36 36 36 38 38 40 40 40 42 42 44 44
2.09 1.92 1.77 1.64 1.53 1.44 1.35 1.28 1.21 1.15 1.10 1.05 1.00
23 9.304 10.098 9.872 9.645 10.422 10.189 10.959 10.721 10.481 11.240 10.996 11.749 11.500
36 38 38 38 40 40 42 42 42 44 44 46 46
2.18 2.00 1.85 1.72 1.69 1.50 1.41 1.33 1.26 1.20 1.14 1.09 1.04 1.00
24 10.037 9.815 10.605 10.378 10.150 10.926 10.692 11.461 11.222 10.982 11.741 11.496 12.249 12.000
38 38 40 40 40 42 42 44 44 44 46 46 48 48
2.27 2.08 1.92 1.79 1.67 1.56 1.47 1.39 1.31 1.25 1.19 1.14 1.09 1.04 1.00
25 9.744 10.547 10.324 11.112 10.884 10.654 11.429 11.195 11.963 11.723 11.483 12.241 11.996 12.750 12.500
38 40 40 42 42 42 44 44 46 46 46 48 48 50 50
2.72 2.50 2.31 2.14 2.00 1.88 1.76 1.67 1.58 1.50 1.43 1.36 1.30 1.25 1.20
30 11.345 12.161 11.943 12.746 12.522 12.299 13.087 12.858 13.638 13.406 13.172 13.942 13.705 14.469 14.228
44 46 46 48 48 48 50 50 52 52 52 54 54 56 56
2.91 2.66 2.46 2.28 2.14 2.00 1.88 1.78 1.68 1.60 1.52 1.45 1.39 1.33 1.28
32 12.812 12.597 12.379 13.188 12.967 13.765 13.539 13.314 14.099 13.869 14.646 14.413 14.178 14.946 14.708
48 48 48 50 50 52 52 52 54 54 56 56 56 58 58
3.18 2.92 2.69 2.50 2.33 2.19 2.06 1.94 1.84 1.75 1.67 1.59 1.52 1.46 1.40
35 13.976 13.761 13.546 14.361 14.141 13.921 14.721 14.497 15.288 15.061 14.833 15.613 15.382 16.155 15.921
52 52 52 54 54 54 56 56 58 58 58 60 60 62 62
3.27 3.00 2.77 2.57 2.40 2.25 2.12 2.00 1.89 1.80 1.71 1.64 1.56 1.50 1.44
36 13.668 14.495 14.279 14.063 14.874 14.653 14.433 15.230 15.006 15.795 15.567 15.338 16.117 15.886 16.658
52 54 54 54 56 56 56 58 58 60 60 60 62 62 64
3.64 3.34 3.08 2.86 2.67 2.50 2.35 2.22 2.10 2.00 1.90 1.82 1.74 1.67 1.60
40 15.561 15.349 15.136 15.961 15.746 15.528 16.339 16.119 16.920 16.697 16.473 17.262 17.035 17.818 17.588
58 58 58 60 60 60 62 62 64 64 64 66 66 68 68
3.82 3.50 3.23 3.00 2.80 2.62 2.47 2.34 2.21 2.10 2.00 1.91 1.83 1.75 1.68
42 15.983 15.773 16.605 16.391 16.177 16.994 16.777 16.557 17.364 17.142 17.939 17.714 17.489 18.275 18.047
60 60 62 62 62 64 64 64 66 66 68 68 68 70 70
4.09 3.75 3.46 3.22 3.00 2.81 2.65 2.50 2.37 2.25 2.14 2.04 1.96 1.88 1.80
45 17.139 16.930 16.719 17.553 17.340 18.161 17.945 17.728 18.536 18.317 18.096 18.895 18.671 19.463 19.237
64 64 64 66 66 68 68 68 70 70 70 72 72 74 74
For Center Distances other than listed in this Table, the Chain Length must be calculated, see Page 265.
H
P-1930-BG 04/10 Boston Gear 800-825-6544 263