The gear ratio for go-karts is a measure of the potential performance of the kart. As the ratio increases, so does the potential top speed. However, power is compromised with an increase in ratio, making top speeds more difficult to achieve, in much the same way that it is hard to climb a hill on a bicycle in high gear. To determine gear ratio, divide the number of clutch teeth by the number of sprocket teeth on the drive axle.
A 6-1 ratio is thought to be the ideal ratio by many go-kart enthusiasts. This means there are six teeth on the rear sprocket for every one tooth in the clutch. This ratio can provide the most speed without compromising power.
In instances of higher gear ratios, such as 4-to-1, the go kart will have very little torque, making it difficult to get going at the start of a race, possibly even requiring a push-start. It will be capable of higher top speeds, but in many cases this will not win a race without quick take-off speed.
Other Important Considerations
In addition to gear ratios, other factors must be considered for optimum top speed, take-off speed and efficiency. Tire size, driver weight, track or terrain conditions, tire tread and overall weight of the go kart will greatly impact the performance of the vehicle.