Gear Ratio Calculator

And Skid Patches...

The Deaf Pigeon Gear Ratio and Skid Patch calculator / table / chart... whatever you want to call it, will help you choose your gearing based on the front chainring tooth count and the rear cog (sprocket) tooth count.

Skid Patch?

The place(s) on the tyre that skid(s) on the road when you lock up your wheel. Based on if you skid with the same foot forward every time (not ambidextrous).

How to use it...

It's really simple. The numbers running horizontally across the top (35 - 53) are the number of teeth on your chainring, and the numbers running vertically down the left hand side is the number of teeth on your rear cog.

Numbers?

The main number in the box is the gear in inches. The green and red numbers are the number of skid patches you will possess with that chosen gearing. Green is obviously good and red is bad.

Up Or Down?

Currently i am running a 48x15 gearing. On this chart that says that i'm currently rocking 86.4 gear inches and 5 skid patches.

If i wanted to potentially ruin my knee's before i hit 40 then i could maybe jump up a gearing on the front. Say... 52? That would give me 93.6 gear inches and 15 skid patches.

That would be pretty silly though. Jumping 7.2 gear inches in one go might be a bit intense, so you'd look at other ways, maybe by dropping a tooth on the rear cog.

--- 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

11

85.9 11 88.4 11 90.8 11 93.3 11 95.7 11 98.2 11 100.6 11 103.1 11 105.5 11 108.0 1 110.5 11 112.9 11 115.4 11 117.8 11 120.3 11 122.7 11 125.2 11 127.6 11 130.1 11

12

78.8 12 81.0 1 83.3 12 85.5 6 87.8 4 90.0 3 92.3 12 94.5 2 96.8 12 99.0 3 101.3 4 103.5 6 105.8 12 108.0 1 110.3 12 112.5 6 114.8 4 117.0 3 119.3 12

13

72.7 13 74.8 13 76.8 13 78.9 13 81.0 1 83.1 13 85.2 13 87.2 13 89.3 13 91.4 13 93.5 13 95.5 13 97.6 13 99.7 13 101.8 13 103.8 13 105.9 13 108.0 1 110.1 13

14

67.5 2 69.4 7 71.4 14 73.3 7 75.2 14 77.1 7 79.1 14 81.0 1 82.9 14 84.9 7 86.8 14 88.7 7 90.6 14 92.6 7 94.5 2 96.4 7 98.4 14 100.3 7 102.2 14

15

63.0 3 64.8 5 66.6 15 68.4 15 70.2 5 72.0 3 73.8 15 75.6 5 77.4 15 79.2 15 81.0 1 82.8 15 84.6 15 86.4 5 88.2 15 90.0 3 91.8 5 93.6 15 95.4 15

16

59.1 16 60.8 4 62.4 16 64.1 8 65.8 16 67.5 2 69.2 16 70.9 8 72.6 16 74.3 4 75.9 16 77.6 8 79.3 16 81.0 1 82.7 16 84.4 8 86.1 16 87.8 4 89.4 16

17

55.6 17 57.2 17 58.8 17 60.4 17 61.9 17 63.5 17 65.1 17 66.7 17 68.3 17 69.9 17 71.5 17 73.1 17 74.6 17 76.2 17 77.8 17 79.4 17 81.0 1 82.6 17 84.2 17

18

52.5 18 54.0 1 55.5 18 57.0 9 58.5 6 60.0 9 61.5 18 63.0 3 64.5 18 66.0 9 67.5 2 69.0 9 70.5 18 72.0 3 73.5 18 75.0 9 76.5 6 78.0 9 79.5 18

19

49.7 19 51.2 19 52.6 19 54.0 1 55.4 19 56.8 19 58.3 19 59.7 19 61.1 19 62.5 19 63.9 19 65.4 19 66.8 19 68.2 19 69.6 19 71.1 19 72.5 19 73.9 19 75.3 19

20

47.3 4 48.6 5 50.0 20 51.3 10 52.7 20 54.0 1 55.4 20 56.7 10 58.1 20 59.4 5 60.8 4 62.1 10 63.5 20 64.8 5 66.2 20 67.5 2 68.9 20 70.2 5 71.6 20

21

45.0 3 46.3 7 47.6 21 48.9 21 50.1 7 51.4 21 52.7 21 54.0 1 55.3 21 56.6 21 57.9 7 59.1 21 60.4 21 61.7 7 63.0 3 64.3 21 65.6 7 66.9 21 68.1 21