The Hybrid Future of Motorcycling

Could this 350-pound, 170-mile-range hybrid be a reality?

Silenthawk Hybrid Motorcycle
The Hybrid Future of MotorcyclingMike Shaffer

There's always been a cliché that all of the coolest technology mankind has come up with is hidden by the government or military. As it happens, motorcycling is no different. Meet the SilentHawk, built in a crevasse located somewhere between military R&D and the motorcycling world, by an engineering and science company called Logos Technologies. Essentially, it's an Alta Redshift MX eBike—a 270-pound, 40-hp, all-electric motocrosser built by Alta Motors in Northern California—that's been toyed with by some pretty smart people.

The key bit of kit that has been adapted is a petroleum-powered, “gen-set range extender.” It’s a tiny, liquid-cooled rotary engine, roughly the size of a grapefruit, weighing about 10 pounds and cranking out around 15 hp and/or 6kW. That means charging the bike’s 5.8kWh battery in the standard 2.5 hours at 240 volts (excluding whatever equipment is plugged in), as long as there’s some fuel in the two-gallon tank.

Silenthawk technologies
As regular as the SilentHawk appears, it includes some unique technology. The self-contained hub motor in the front wheel, for one. The next version will likely have a control screen rather than old-school switches.Mike Shaffer

What kind of fuel? It actually doesn’t really matter. Kerosene, gasoline, diesel, jet fuel—the engine doesn’t really care; it just needs a heads up for what to expect so it knows how to start. “Once the engine starts it will automatically regulate itself to all of that,” says Alex Dzwill, Logos’ lead engineer for SilentHawk, adding casually, “it has a really complicated ECU.” Running on any fuel is a key facet for the military so that soldiers in the field can use whatever they find. Interestingly, Dzwill said that efficiency isn’t affected by different fuel.

The technique of using the combustion engine as a generator rather than propulsion is alive already. It’s a very similar system to the one used in BMW’s i3 electric car, which has an option for a two-cylinder engine to pump out electricity and keep the battery charged.

Where the i3 is two-wheel drive, the SilentHawk employs a nifty trick to become all-wheel drive. It uses an independent hub-powered front wheel that is controlled by the bike and can deliver up to 7 hp to the front contact patch. It’s a self-contained unit, driven separately from the Alta motor and rear wheel, and can be turned on or off by the rider.

Silenthawk Hybrid Motorcycle Close up
The Hybrid Future of MotorcyclingMike Shaffer

ADV types will appreciate that there are auxiliary plugs for equipment strewn all over the bike. It was designed for charging communication and navigation equipment for military use, but then again the same goes for civilian riders.

Another interesting slice of the hybrid technology on the SilentHawk is its ability to automatically charge its batteries and gear when it’s parked. Again, designed for military use (mostly as a communication beacon) so that the bike can recharge without being ridden or turned on. Phase two of this project is set to include an air-cooled rotary engine that’s smaller and lighter, as well as updating all of the power-generation hardware to be more compact and efficient.

The potential application for civilian use is clear to see. A hybrid motorcycle that weighs 350 pounds, with a range of around 170 miles that will recharge itself and anything you leave plugged into it while it sits in your parking lot at work is a pretty attractive proposition. Not to mention a little more fuel would add range and still be well underweight for most motorcycles on the road today. Who knows what else they might have in the basement?