Learn How A Motorcycle Clutch Works

Manual transmissions are a dying breed in the four-wheeled world, but we motorcyclists still use them as our primary method of connecting engines to wheels. We learn clutch control from day one of the MSF, where we're told that bike clutches are more forgiving than their car equivalents, but we're not told why. What's so different about a motorcycle clutch? Why are they happier to be feathered than car clutches?

The answer comes from their design, which is vastly different from a clutch you'd find in a car. Bike clutches are multi-layered, with far more discs than even the highest-horsepower modified Subarus, which gives them some extra torque-holding capacity for their overall size. The big difference, though, is that bike clutches are bathed in engine oil while car clutches sit perfectly dry in the transmission bellhousing. Watch Ari Henning run you through the basics:

All those discs let the clutch handle more torque than a single disk of equivalent size ever could. The constant oil bath keeps temperatures steady, making it harder to burn out a bike clutch — that's why bikes are more amenable to being feathered or partially engaged, which can be a godsend for metering power over difficult terrain off road. Driving a car with the clutch partially engaged is a death knell, but on a bike it's standard dirt operating procedure.

Henning also points out that this wet clutch design means you need to be pickier in the oil you put in your bike. Since engine oil is shared with the clutch, owners need to be careful about using lubricants that have friction modifiers — common enough in cars and limited-slip differentials, but they can mess with your bike's powertrain in unexpected ways. Bikes need bike oil, because that clutch design is actually affected by the choices you make. Unless you ride a KLR, in which case you should just fill it with Rotella T6 like a Subaru and call it a day.