Gear Ratio Chart/Pinion Gear Selection - Evader ST/BX With 88T Spur
Internal Gear Ratio 2.66
  Off-Road Tires Street Tires Foam Tires * Off-road calcs = Gladiator II tires w/ 4.25" diameter
Roll-out 13.352 10.996 9.425 * Street calcs = Street Hawg II tires w/ 3.5" diameter
* Foam calcs = Generic foam tires w/ 3.0" diameter
Final Drive Ratios
Pinion FDR (*:1) Pinion FDR (*:1)
15 15.605 21 11.147
16 14.630 22 10.640
17 13.769 23 10.177
18 13.004 24 9.753
19 12.320 25 9.363
20 11.704 26 9.003
Efficiency Ratio1
Pinion FDR:RO - Off-Road Pinion FDR:RO - Street Pinion FDR:RO - Foam
15 1.169 15 1.419 15 1.656
16 1.096 16 1.331 16 1.552
17 1.031 17 1.252 17 1.461
18 0.974 18 1.183 18 1.380
19 0.923 19 1.120 19 1.307
20 0.877 20 1.064 20 1.242
21 0.835 21 1.014 21 1.183
22 0.797 22 0.968 22 1.129
23 0.762 23 0.926 23 1.080
24 0.730 24 0.887 24 1.035
25 0.701 25 0.852 25 0.993
26 0.674 26 0.819 26 0.955
1 Ideal Efficiency Ratio is closest to 1:1.  Depending on the kV of your motor, you may need to gear up or down to find the sweet spot.
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