The speed ratio of straight bevel gears varies by application. It is determined by the number of teeth on each gear and is calculated using the following formula: Ratio = Number of teeth on driving gear / Number of teeth on driven gear.
The most common ratios for straight bevel gears are 1:1, 2:1, 3:2 and 4:3. However, other ratios may be used depending on specific application requirements. Typically, lower gear ratios are used for high torque applications and higher gear ratios are used for high speed applications.