Vespa Gear Calculator

Smallframe, Largeframe and Wideframe. Change any cog, primary or tyre value and the results update instantly.

Frame family

Model / gearbox

Tyre

Primary & engine

Primary drive cog

Primary driven cog

Primary ratio

Engine RPM

Custom tyre diameter (mm)

Max chart RPM

Gearbox cogs

Drive = layshaft / cluster cog. Driven = gear cog on the mainshaft.

Gear	Drive	Driven	Gear ratio	Overall ratio	Speed

Speed chart

Speed table

The calculator uses: primary ratio = driven ÷ drive; overall ratio = primary × gear ratio; speed = wheel RPM × tyre circumference. Values are theoretical and do not account for tyre growth, slip, drag or drivetrain losses.