Horsepower (hp)

Horsepower is a traditional unit of power, describing how fast an engine can do work. Several versions exist: metric horsepower (PS, hv) equals about 0.735 kW, while the imperial or mechanical horsepower (hp, bhp) equals about 0.746 kW. Official EU documents state engine power in kilowatts.

Power is calculated from torque and engine speed, which is why engines often reach peak power near the top of the rev range. Manufacturer figures are usually measured at the crankshaft; a dyno measures less at the rear wheel because of drivetrain losses.

Peak horsepower says little about how a bike feels. The shape of the power and torque curves, weight and gearing matter just as much for real-world performance.