GEAR RATIO CHART

The following chart can be used to assist with gearing at the track.  Different size drive (engine) sprockets require a different rear gear to maintain the same gear ratio.

EXAMPLE :-

You have a 9 tooth drive (engine) sprocket and you change to a 10 tooth sprocket.  The rear gear you have been using is 82 teeth.  Read across the line with the 82 gear to the column headed 9 tooth.  The ratio is 9.11.  Now read down the column headed 10 tooth until you find a number nearest to 9.11.  In this example it is 9.10.  Now read left across the line to the Gear column to find the number.  In this example it is 91.  Therefore a new rear gear of 91 teeth is required to maintain a constant gear ratio to the track with the new 10 tooth drive sprocket.

 
Rear Gear 9 Tooth 10 Tooth 11 Tooth 12 Tooth 13 Tooth 14 Tooth 15 Tooth
67 7.44 6.70 6.09 5.58 5.15 4.78 4.46
68 7.55 6.80 6.18 5.66 5.23 4.85 4.53
69 7.66 6.90 6.27 5.75 5.30 4.92 4.60
70 7.77 7.00 6.36 5.83 5.38 5.00 4.66
71 7.88 7.10 6.45 5.91 5.46 5.07 4.73
72 8.00 7.20 6.54 6.00 5.53 5.14 4.80
73 8.11 7.30 6.63 6.08 5.61 5.21 4.86
74 8.22 7.40 6.72 6.16 5.69 5.28 4.93
75 8.33 7.50 6.81 6.25 5.76 5.35 5.00
76 8.44 7.60 6.90 6.33 5.84 5.42 5.06
77 8.55 7.70 7.00 6.41 5.92 5.50 5.13
78 8.66 7.80 7.09 6.50 6.00 5.57 5.20
79 8.77 7.90 7.18 6.58 6.07 5.64 5.26
80 8.88 8.00 7.27 6.66 6.15 5.71 5.33
81 9.00 8.10 7.36 6.75 6.23 5.78 5.40
82 9.11 8.20 7.45 6.83 6.30 5.85 5.46
83 9.22 8.30 7.54 6.91 6.38 5.92 5.53
84 9.33 8.40 7.63 7.00 6.46 6.00 5.60
85 9.44 8.50 7.72 7.08 6.53 6.07 5.60
86 9.55 8.60 7.81 7.16 6.61 6.14 5.73
87 9.66 8.70 7.90 7.25 6.69 6.21 5.80
88 9.77 8.80 8.00 7.33 6.76 6.28 5.86
89 9.88 8.90 8.09 7.41 6.84 6.35 5.93
90 10.00 9.00 8.18 7.50 6.92 6.42 6.00
91 10.11 9.10 8.27 7.58 7.00 6.50 6.06
92 10.22 9.20 8.36 7.66 7.07 6.57 6.13
93 10.33 9.30 8.45 7.75 7.15 6.64 6.20
94 10.44 9.40 8.54 7.83 7.23 6.71 6.26
95 10.55 9.50 8.63 7.91 7.30 6.78 6.33