Brammo Empulse R | First Ride

They say: “Modern and unique, yet reassuringly familiar.”
We say: “Gears and a clutch make a real electric motorcycle.”

The most common criticism of electric bikes is that they don’t feel like “real motorcycles.” The magic-carpet character of a silent, vibration-free motor with a tabletop-flat torque curve is novel and even exhilarating, but especially for experienced motorcyclists this can seem dull compared to a screaming, slightly unpredictable gas engine. There’s also the fact that every eBike built to date has been single-speed, eliminating the skill required for—and the autonomy that results from—shifting gears. It’s just not the same.

Electric vehicles don’t need transmissions. Because torque in an electric motor is a function of current and not rotational speed, there’s little need to manipulate engine rpm to build or control power. Max torque is essentially available from zero rpm, and power output is controlled digitally by the motor controller to make it tractable. Single-speed drivetrains also save the considerable cost and complexity of having to design, engineer, and manufacture a transmission.

That's not to suggest, however, that an eBike wouldn't benefit from a gearbox. A single ratio inherently compromises acceleration or top speed—you can't optimize for both at the same time. There's an efficiency cost, too. Then there's the riding experience—shifting gears makes a bike more dynamic, more fun...more motorcycle. So when Brammo set to work designing the Empulse, its most ambitious electric motorcycle yet, adding a six-speed transmission was a priority. The Empulse would not only offer performance parity with an internal combustion engine (ICE) bike, it would deliver a similar riding experience, too.

A top speed over 100 mph and useful range approaching 100 miles puts the Brammo on parity with the latest Zero models and closes the gap to ICE bikes. The Empulse looks like a proper motorcycle, too, with an aggressive streetfighter design that accurately transmits the Empulse’s performance potential. “We didn’t want to style a superbike replica and then have the performance let buyers down,” says Brammo Director of Product Development, Brian Wismann. “We wanted it to look like what it is—an honest, fun, urban streetfighter.”

I rode the Empulse shortly after attending the Triumph Street Triple R press launch last November, and commented on how similar the two bikes felt. This wasn’t coincidental, Wismann explained—Brammo actually benchmarked the Street Triple prior to designing the Empulse, and the ergonomics and chassis geometry are very similar. The major differences are the Empulse’s slightly longer wheelbase to make room for all that battery, and a slightly lower, narrower handlebar.

I spent a half-day riding the Empulse around San Francisco, subjecting it to steep hills, repeated full-throttle launches in stop-and-go traffic, and some spirited sport riding around Twin Peaks—exactly the mixed-urban usage that Brammo intends for this bike. It was the perfect real-world test of the Empulse’s performance claims, and an excellent opportunity to see how adding a transmission enhances the eBike experience.

First things first: You don’t use the Empulse transmission like you would a conventional motorcycle’s. The clutch is needed only to shift gears—and shifting gears is completely optional. Because the electric motor delivers such a broad spread of torque, it’s possible to ride the Empulse smoothly, at least in an urban setting, in any gear. The only difference is the rate of acceleration. Establishing forward movement is still a twist-and-go affair—there’s no need to use the clutch coming to or leaving from a stop.

I find this problematic at first. I simply can’t break the habit of pulling in the clutch at every stop and then slipping it as I pull away, which only causes the engine to spin up without creating forward motion. Wismann is actually pleased to hear I had so much trouble: “That only tells me that we accomplished our goal of making it feel like a real motorcycle!”

Once I finally learn to ignore the lever and just twist the throttle, I’m fairly amazed at how hard the Empulse jumps off the line. Brammo claims 60 lb.-ft. of torque at the peak, but the term “peak” isn’t applicable here. The torque output is digitally restricted until 4500 rpm, when it enters what Brammo refers to as a “continuous power region” where the curve remains essentially flat, without peaking or falling, right to the 8200-rpm redline. This makes the Empulse feels like it accelerates significantly harder, and for significantly longer, than any ICE bike with a similar torque output. It might only have a 100-mph top speed, but it feels like it gets there as quickly as any superbike.

Utilizing the six-speed gearbox only enhances acceleration, despite slightly notchy shift action. And since peak motor efficiency occurs between 5000 and 6000 rpm, multiple gear ratios make it easier to keep the Empulse operating at maximum efficiency over a wider range of speeds, to help maximize range. The Empulse is rated at 438 MPGe (miles-per-gallon gasoline equivalent), which translates to a claimed range of 121 city/56 highway/77 combined. I rode just more than 40 aggressive miles in San Francisco’s challenging, mixed-urban environs and returned to Scuderia West with 40 percent of the battery charge remaining. Still worried about being left for dead? All Empulse buyers will receive a free two-year roadside assistance membership with Motorcycle Towing Services (MTS).

With aggressive geometry and high-end running gear from Marchesini, Marzocchi, Sachs, and Brembo, the Empulse is fun and easy to ride fast. Steering is neutral and predictable, and the suspension is firm and perfectly balanced despite the fork and shock being sourced from different firms. Things only got twisted in the most technical corners, where you were reminded the Empulse weighs a stout 470 pounds (claimed). The weight distribution feels biased toward the front, as it takes some effort to initiate tight turns and it can occasionally be hard to stop the bike from turning without adding a bit of throttle.

Overall, the Empulse R is a remarkably fun bike that finally combines the futuristic, TIE-fighter appeal of electric propulsion with the dynamic excitement and interaction of a traditional ICE bike. And the future is now: The first customer Empulse was delivered December of last year, and at press time the company was building 10 bikes per day in its existing Ashland, OR, facility; a new, 100,000 square-foot production facility opening in mid-2013 in nearby Talent, OR, is expected to allow the firm to deliver 2000 bikes this year, Wismann says.

TECH SPEC

EVOLUTION
Chassis and engine technology borrowed from Brammo's TTXGP racer, cloaked in streetfighter styling, and finished with the first Integrated Electric Transmission.

RIVALS
Zero S

VERDICT 4 out of 5 stars
Six speeds, serious acceleration, credible top speed, and (almost) real-world range make this the most dynamic and exciting eBike yet.

HARD PARTS

BRAMMO EMPULSE R
Under the Skin of the World's Most Advanced Electric Motorcycle

MOTOR
The Empulse motor is designed by Brammo and built by Parker-Hannifin in New Ulm, MN. Essentially a scaled-down version of what's in Brammo's 170-mph electric superbike that won the 2012 TTXGP World Championship at Daytona, the permanent-magnet AC motor uses a samarium-cobalt magnet and is liquid cooled—a first for a production electric bike. It produces 40 kilowatts of energy at 8200 rpm—equivalent to 54 horsepower—with a peak torque rating of 60.5 lb.-ft. that remains constant from 4500 through 8200 rpm. A Sevcon Gen 4 digital motor controller moderates the power supply with Advanced Flux Vector control—shades of Back to the Future—to smoothly channel power from battery to motor.

BATTERY
The Empulse carries Brammo's latest BPM 15/90 lithium-ion battery: a 103.2-volt battery that delivers 90 amp-hours storage and a nominal battery capacity of 9.3 kilowatt-hours. The battery pack is constructed from 252 individual pouch cells grouped in seven modules. The individual cells are rectangular, with each presenting a large, flat surface that can be heated or cooled via heat-transfer plates running through the module extrusions. Very cold temperatures can decrease charging efficacy of lithium-ion batteries, and these heat transfer plates can bring the battery modules up to a temperature that allow full-rate charging even if the bike is stored outside in below-freezing temperatures, which Brammo says is crucial for customer satisfaction.

CONTROLS
A Hall-effect electronic throttle (ride-by-wire) allows Brammo to offer two power modes: Sport mode delivers 10 percent more peak power, and reaches peak output 25 percent sooner than Normal mode. Regenerative braking effect, which uses deceleration forces to recharge the battery and also mimics a gas engine's compression-braking for a more familiar riding experience, is reduced in Normal mode for a smoother ride at low speeds around the city. A handlebar-mounted switch changes modes. The Empulse also incorporates an on-board diagnostics system that service techs can access directly by connecting a laptop to the bike. Alternately, the bike owner can download files from a USB drive located under the seat and e-mail these to the dealer for diagnostic purposes.

CHARGING SYSTEM
The Empulse is charged using a SAE-standard J1772 connector that's included with the bike, which feeds into a 3 kW on-board charger and DC-DC converter. This is the same charging interface used on electric cars like the Nissan Leaf and Chevy Volt, so Empulse owners can take advantage of the ever-increasing number of public charging stations being installed across the United States. Using a Level 1 power supply (single-phase 120-volt, like most household outlets), it takes 8 hours to fully charge the depleted battery; connecting to a Level 2 power supply (split-phase 240-volt, like most dedicated charging stations) reduces that charging interval to 3.5 hours. The charging connector, which looks remarkably like a gas pump nozzle, plugs into an outlet under what would be the gas cap on a conventional fuel tank.

TRANSMISSION
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.

CHASSIS:
Accossato in Italy fabricates the aluminum E-Beam frame, tubular-steel subframe, and tubular-steel swingarm. Making enough room for a large battery pack is always challenging on eBikes, and adding a transmission here ate up even more available space. Brammo's solution was to widen the frame by 2 inches (compared to the original, direct-drive Empulse prototype) to make enough space for the BPM battery. The remainder of the chassis components are premium European parts befitting a $19,000 sportbike, including radial-mount Brembo brakes, Marchesini wheels, a Marzocchi fork, and Sachs rear shock (the latter two components both fully adjustable on the R-version).