TOOTHMAP
The drive

Watch the gearing turn

Crank, clutch, the gear pair you selected, front sprocket, chain, rear sprocket, wheel — every body turning at its true relative rate for the sprockets you pick. How the numbers are made.

Drivetrain bench

Exact ratio math · tooth shape and case layout modeled

Schematic view — crank pinion, clutch basket, the engaged pair, front sprocket, chain, rear sprocket and wheel. The animated bench needs WebGL; every number below is the same either way.

The bench is decorative; every number it shows is in the readouts and the data table below.

The multiplication

Primary × Gear × Final = Crank : wheel

What that means

Road speed
Engine
Gear

· modeled · 585 mm nominal centres · nominal

Controls

Front
Rear
Gear

Scene runs at 1/71 speed · all ratios exact · gearbox spread along the shaft · one pair shown, a real box has six, all constantly meshed · tooth profile and case dimensions modeled

Back to the numbers