Know your three ratios
External ratio = spur ÷ pinion; FDR = external × internal ratio. Only the FDR decides wheel speed — see gear ratio explained if unsure.
Step 1 — measure the baseline
Enter your current gearing into the Gear Ratio Calculator and the Speed Calculator. Record the FDR.
Step 2 — change one thing
Pinion up = taller gearing = more theoretical speed. Change 1–2 teeth, recompute, test-run 2–3 minutes, check motor temperature.
Step 3 — iterate
Repeat while the motor stays in its temperature range. If it climbs past ~80 °C on touch or the ESC thermal-protects, gear down.
Safety
More speed means more energy — check tires, bearings and battery leads are in good condition before a tall-geared run.