Brammo's super-compact, six-speed Integrated Electric Transmission (IET) was developed in partnership with SMRE Engineering of Perugia, Italy. This so-called "mechatronic propulsion unit" is a small feat of engineering, combining electronic propulsion with a mechanical transmission that uses a conventional wet, multi-plate clutch and gear mechanisms. Sophisticated software and a dedicated electronic control system vary power supply and engine response according to gear position to more closely mimic the dynamic riding feel of an internal-combustion engine. Brammo originally envisioned a four-speed transmission, but settled on six ratios to reduce stress on the motor and control system. Generating torque from an electric motor requires precise tracking of the rotor position, which proved difficult when the rotor was forced to make bigger speed jumps from gear to gear. Six closely spaced ratios make it easier to track rotor position more precisely, reducing the risk of a controller fault. For packaging reasons, neutral is located between second and third gears, but since you hardly ever use neutral on this bike—the electric motor is essentially in neutral any time you're off throttle, including at a stop—this unusual layout is mostly a non-issue. The transmission adds a service requirement to an otherwise maintenance-free drivetrain—its oil needs to be changed every 3000 miles, but because it only holds one liter and the closed system requires no filter, this is a quick and easy task.