How Harley’s LiveWire got its soul
How H-D have given their electric bike a soul
We all know that our beloved piston power is what gives motorcycles their soul and everything else is just a side order. But with no banging V-twin to keep to you engaged, Harley-Davidson have had to artificially inject their new LiveWire electric bike with a bit of all-American character. Electric motors are more or less silent, so they’ll never set off car alarms like an open-piped airbox-sucking petrol engine. There was speculation that you’d be able to choose the sound the LiveWire makes from a number of pre-selected soundtracks (presumably you could make it sound like anything from Rossi’s M1 to a chicken), that would be broadcast from speakers on the Harley’s tail unit but no such thing ever made it to production. Instead, Harley have engineered in some mechanical noise, through the only part of the LiveWire’s drivetrain that resembles a normal motorcycle power train: its gearbox.
To keep the chassis slim, the LiveWire’s electric motor is mounted longitudinally in the frame – just like a Moto Guzzi or BMW’s boxers. But unlike those bikes, the Harley needs a 90-degree gearset to turn the front sprocket, rather than a shaft drive to the rear wheel. To do this, the LiveWire uses bevel-shaped cogs, which whine (like a car in reverse) and scream the faster you go, giving the bike
‘Bevel-shaped cogs scream like a jet fighter’
a jet fighter-like sound, which is both impressive and slightly sinister in equal measure. There’s no clutch to engage the drive, nor is there a traditional multi-speed gearbox, instead there’s a single speed step-down gearbox with a 9.71:1 reduction ratio. Once out of the bevel, power gets to the ground via a typically Harley belt drive, itself running a 3:1 ratio between the front and rear drive sprockets. That means a twist of the throttle will see the power surging from zero right up to the 115mph limiter in one seamless tide of uninterrupted drive. And while most electric motors are completely silent and passive when not on the move, the LiveWire’s motor has what the Milwaukee firm calls a ‘haptic pulse’ that resonates through the chassis like a throbbing heartbeat. It’s not quite the famous Harley-Davidson V-twin ‘potato-potato’ accompaniment at the traffic lights, more of a computer chip.
The LiveWire does this by electrically jolting the motor, causing it to slightly accelerate and decelerate, which creates a torque reaction that rocks the bike with a gentle rhythmic pulse – again a bit like the lateral lurch you get from revving a BMW boxer at standstill. Once you pull away the pulsing action stops, leaving you to surf the smooth delivery to the accompanying soundtrack of the screaming drive train and the wind whistling through your beard.