Gear Ratio Calculator

Gear Chart and Calculations

The calculations below are approximate for 700c & 27 Inch wheels.

To calculate the exact gearing, divide the number of chainring teeth by the number of sprocket teeth and multiply the answer by the actual rolling diameter of the tyred wheel. (Divide actual rolling circumference by 3.142 to calculate rolling diameter)

Sprocket 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 38
Chainring
20 49.1 45 41.5 38.6 36 33.8 31.8 30 28.4 27 25.7 24.5 23.5 22.5 21.6 20.8 20 19.3 18.6 18 17.4 16.9 16.4 15.9 14.2
21 51.5 47.3 43.6 40.5 37.8 35.4 33.4 31.5 29.8 28.4 27 25.8 24.7 23.6 22.7 21.8 21 20.3 19.6 18.9 18.3 17.7 17.2 16.7 14.9
22 54 49.5 45.7 42.4 39.6 37.1 34.9 33 31.3 29.7 28.3 27 25.8 24.8 23.8 22.8 22 21.2 20.5 19.8 19.2 18.6 18 17.5 15.6
23 56.5 51.8 47.8 44.4 41.4 38.8 36.5 34.5 32.7 31.1 29.6 28.2 27 25.9 24.8 23.9 23 22.2 21.4 20.7 20 19.4 18.8 18.3 16.3
24 58.9 54 49.8 46.3 43.2 40.5 38.1 36 34.1 32.4 30.9 29.5 28.2 27 25.9 24.9 24 23.1 22.3 21.6 20.9 20.3 19.6 19.1 17.1
25 61.4 56.3 51.9 48.2 45 42.2 39.7 37.5 35.5 33.8 32.1 30.7 29.3 28.1 27 26 25 24.1 23.3 22.5 21.8 21.1 20.5 19.9 17.8
26 63.8 58.5 54 50.1 46.8 43.9 41.3 39 36.9 35.1 33.4 31.9 30.5 29.3 28.1 27 26 25.1 24.2 23.4 22.6 21.9 21.3 20.6 18.5
27 66.3 60.8 56.1 52.1 48.6 45.6 42.9 40.5 38.4 36.5 34.7 33.1 31.7 30.4 29.2 28 27 26 25.1 24.3 23.5 22.8 22.1 21.4 19.2
28 68.7 63 58.2 54 50.4 47.3 44.5 42 39.8 37.8 36 34.4 32.9 31.5 30.2 29.1 28 27 26.1 25.2 24.4 23.6 22.9 22.2 19.9
29 71.2 65.3 60.2 55.9 52.2 48.9 46.1 43.5 41.2 39.2 37.3 35.6 34 32.6 31.3 30.1 29 28 27 26.1 25.3 24.5 23.7 23 20.6
30 73.6 67.5 62.3 57.9 54 50.6 47.6 45 42.6 40.5 38.6 36.8 35.2 33.8 32.4 31.2 30 28.9 27.9 27 26.1 25.3 24.5 23.8 21.3
31 76.1 69.8 64.4 59.8 55.8 52.3 49.2 46.5 44.1 41.9 39.9 38 36.4 34.9 33.5 32.2 31 29.9 28.9 27.9 27 26.2 25.4 24.6 22
32 78.5 72 66.5 61.7 57.6 54 50.8 48 45.5 43.2 41.1 39.3 37.6 36 34.6 33.2 32 30.9 29.8 28.8 27.9 27 26.2 25.4 22.7
33 81 74.3 68.5 63.6 59.4 55.7 52.4 49.5 46.9 44.6 42.4 40.5 38.7 37.1 35.6 34.3 33 31.8 30.7 29.7 28.7 27.8 27 26.2 23.4
34 83.5 76.5 70.6 65.6 61.2 57.4 54 51 48.3 45.9 43.7 41.7 39.9 38.3 36.7 35.3 34 32.8 31.7 30.6 29.6 28.7 27.8 27 24.2
35 85.9 78.8 72.7 67.5 63 59.1 55.6 52.5 49.7 47.3 45 43 41.1 39.4 37.8 36.3 35 33.8 32.6 31.5 30.5 29.5 28.6 27.8 24.9
36 88.4 81 74.8 69.4 64.8 60.8 57.2 54 51.2 48.6 46.3 44.2 42.3 40.5 38.9 37.4 36 34.7 33.5 32.4 31.4 30.4 29.5 28.6 25.6
37 90.8 83.3 76.8 71.4 66.6 62.4 58.8 55.5 52.6 50 47.6 45.4 43.4 41.6 40 38.4 37 35.7 34.4 33.3 32.2 31.2 30.3 29.4 26.3
38 93.3 85.5 78.9 73.3 68.4 64.1 60.4 57 54 51.3 48.9 46.6 44.6 42.8 41 39.5 38 36.6 35.4 34.2 33.1 32.1 31.1 30.2 27
39 95.7 87.8 81 75.2 70.2 65.8 61.9 58.5 55.4 52.7 50.1 47.9 45.8 43.9 42.1 40.5 39 37.6 36.3 35.1 34 32.9 31.9 31 27.7
40 98.2 90 83.1 77.1 72 67.5 63.5 60 56.8 54 51.4 49.1 47 45 43.2 41.5 40 38.6 37.2 36 34.8 33.8 32.7 31.8 28.4
41 100.6 92.3 85.2 79.1 73.8 69.2 65.1 61.5 58.3 55.4 52.7 50.3 48.1 46.1 44.3 42.6 41 39.5 38.2 36.9 35.7 34.6 33.5 32.6 29.1
42 103.1 94.5 87.2 81 75.6 70.9 66.7 63 59.7 56.7 54 51.5 49.3 47.3 45.4 43.6 42 40.5 39.1 37.8 36.6 35.4 34.4 33.4 29.8
43 105.5 96.8 89.3 82.9 77.4 72.6 68.3 64.5 61.1 58.1 55.3 52.8 50.5 48.4 46.4 44.7 43 41.5 40 38.7 37.5 36.3 35.2 34.1 30.6
44 108 99 91.4 84.9 79.2 74.3 69.9 66 62.5 59.4 56.6 54 51.7 49.5 47.5 45.7 44 42.4 41 39.6 38.3 37.1 36 34.9 31.3
45 110.5 101.3 93.5 86.8 81 75.9 71.5 67.5 63.9 60.8 57.9 55.2 52.8 50.6 48.6 46.7 45 43.4 41.9 40.5 39.2 38 36.8 35.7 32
46 112.9 103.5 95.5 88.7 82.8 77.6 73.1 69 65.4 62.1 59.1 56.5 54 51.8 49.7 47.8 46 44.4 42.8 41.4 40.1 38.8 37.6 36.5 32.7
47 115.4 105.8 97.6 90.6 84.6 79.3 74.6 70.5 66.8 63.5 60.4 57.7 55.2 52.9 50.8 48.8 47 45.3 43.8 42.3 40.9 39.7 38.5 37.3 33.4
48 117.8 108 99.7 92.6 86.4 81 76.2 72 68.2 64.8 61.7 58.9 56.3 54 51.8 49.8 48 46.3 44.7 43.2 41.8 40.5 39.3 38.1 34.1
49 120.3 110.3 101.8 94.5 88.2 82.7 77.8 73.5 69.6 66.2 63 60.1 57.5 55.1 52.9 50.9 49 47.3 45.6 44.1 42.7 41.3 40.1 38.9 34.8
50 122.7 112.5 103.8 96.4 90 84.4 79.4 75 71.1 67.5 64.3 61.4 58.7 56.3 54 51.9 50 48.2 46.6 45 43.5 42.2 40.9 39.7 35.5
51 125.2 114.8 105.9 98.4 91.8 86.1 81 76.5 72.5 68.9 65.6 62.6 59.9 57.4 55.1 53 51 49.2 47.5 45.9 44.4 43 41.7 40.5 36.2
52 127.6 117 108 100.3 93.6 87.8 82.6 78 73.9 70.2 66.9 63.8 61 58.5 56.2 54 52 50.1 48.4 46.8 45.3 43.9 42.5 41.3 36.9
53 130.1 119.3 110.1 102.2 95.4 89.4 84.2 79.5 75.3 71.6 68.1 65 62.2 59.6 57.2 55 53 51.1 49.3 47.7 46.2 44.7 43.4 42.1 37.7
54 132.5 121.5 112.2 104.1 97.2 91.1 85.8 81 76.7 72.9 69.4 66.3 63.4 60.8 58.3 56.1 54 52.1 50.3 48.6 47 45.6 44.2 42.9 38.4
55 135 123.8 114.2 106.1 99 92.8 87.4 82.5 78.2 74.3 70.7 67.5 64.6 61.9 59.4 57.1 55 53 51.2 49.5 47.9 46.4 45 43.7 39.1
56 137.5 126 116.3 108 100.8 94.5 88.9 84 79.6 75.6 72 68.7 65.7 63 60.5 58.2 56 54 52.1 50.4 48.8 47.3 45.8 44.5 39.8
57 139.9 128.3 118.4 109.9 102.6 96.2 90.5 85.5 81 77 73.3 70 66.9 64.1 61.6 59.2 57 55 53.1 51.3 49.6 48.1 46.6 45.3 40.5
58 142.4 130.5 120.5 111.9 104.4 97.9 92.1 87 82.4 78.3 74.6 71.2 68.1 65.3 62.6 60.2 58 55.9 54 52.2 50.5 48.9 47.5 46.1 41.2
59 144.8 132.8 122.5 113.8 106.2 99.6 93.7 88.5 83.8 79.7 75.9 72.4 69.3 66.4 63.7 61.3 59 56.9 54.9 53.1 51.4 49.8 48.3 46.9 41.9
60 147.3 135 124.6 115.7 108 101.3 95.3 90 85.3 81 77.1 73.6 70.4 67.5 64.8 62.3 60 57.9 55.9 54 52.3 50.6 49.1 47.6 42.6

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Gear Ratio Calculator

Gear Ratio Calculator

The calculations below are approximate for 700c & 27 Inch wheels. To calculate the exact gearing, divide the number of chainring teeth by the number

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