Taking the roar out of the crowd: Hybrid Motorcycles

March 8, 2007
Hybrid motorcycles won't roar their way to popularity … but that won't stop 'em.

Associate Editor

Concept eC1 descended from the Honda Super 90 step-through design of the early '60s that put a generation of mainstream consumers on two wheels.

Concept eC2 captures the flavor of a sportbike while retaining the same large seat and comfortable handlebar of eC1. It has minimal bodywork and a light, nose-down attitude.

Concept eC3 is a commuter variation that adds wind protection, integrated tail rack, and side cases. The upper assembly is cantilevered from the top of the monocoque structure.

The custom wheels, front swingarm assembly, and SolidSlot brushless motor/generator in eCycle's concept hybrid.

For diehards, there's nothing like the death-rattle of a Harley Davidson. For others, a quiet — not to mention relatively guilt-free — ride is more to their liking. This stealthy cruising comes courtesy of hybrid technology. Hybrids, of course, aren't new, but a quiet motorcycle . . . that's a revolution. eCycle Inc., Temple, Pa., believes that simple design and low costs will expand hybrids into markets beyond automotive. The company designed the powertrain going into what may be the first-ever hybrid motorcycle. The bike's design comes from MachineArt in Frenchtown, N.J.

The first-generation bike (1996) was an all-electric model with a conventional fork design. Power came from a 144-V battery. Top speed was 80 mph, with a 25-mile range/charge. The second-generation (2000) model, a hybrid, also topped out at 80 mph. But the hybrid went 150 miles on a gallon of gas. The third-generation concept should be ready later this year.

Under the direction of eCycle President Daniel Sodomsky, MachineArt head designer Andrew Serbinski created several styles of the new concept. The goal was to design a platform that was advanced but not intimidating to consumers. The result delivers 150 mpg with front and rear swing arms and no front fork. The monocoque frame, according to the company, can be more rigid than one made of welded tubing and serves as a heat sink and fuel tank.

The company says its new platform promises to be its most reliable and powerful yet. Unlike typical motorcycles, the hybrid concept has a bank of batteries; a gasoline, propane, or diesel engine; a brushless motor/generator; and a two-speed gearbox.

The versatile powertrain can run more than motorcycles. ATVs, small commuter cars, airport baggage vehicles, and lawn-maintenance vehicles are all fair game. And adding a 120-Vac inverter could let the vehicles double as mobile auxiliary power units, bringing power to construction sites, campgrounds, and other remote locations.

The Concept eCycle uses what's called a SolidSlot brushless motor/generator as a key ingredient. Named for its design, the motor/generator has solid bars of aluminum linked with copper end turns in lieu of traditional copper windings. Slot fill exceeds 90%, compared to less than 50% for traditional windings. This results in super-low resistance and high current capacity.

Unlike other brushless motors, the SolidSlot operates at low voltages (12 to 36 Vdc) and current up to 450 A. Performance comparable to brush-dc motors can come with as little as one-third of the current. And the motors are typically about one-fifth of the size and mass of conventional motors.

The electric motor produces 23 Nm/17 lb-ft of torque. The transmission and final drive convert this to 288 Nm/212 lb-ft in low gear. Batteries constantly recharge while the vehicle operates. The simple addition of a battery charger converts the bike to a plug-in hybrid.

In front, an inside-out rotor with opposed piston caliper and Performance Friction pads handle braking. Eliminating the traditional engine and transmission let eCycle designers use a strong, lightweight, and easy-to-machine structure to join front and rear-suspension hard points. The forkless chassis makes efficient use of space while reducing mass.

The bike operates much like today's hybrid automobiles. The electric motor handles torque demands during acceleration and passing. An internal combustion engine handles cruising and charges the batteries. The bike can be programmed for all-electric operation for limited distances. The company expects the bike will perform much like a cycle powered by a 250-cc gas engine, except for top speed (80 mph on the hybrid). Fuel consumption is estimated at 150 mpg, with significantly lower emissions.

eCycle's primary goal is to produce a hybrid motorcycle platform that will interest early-adopters. It is also working on developments that it hopes will stake out a role for hybrids in other powersports vehicles.

The front suspension configuration was inspired by the work of motorcycle authority Tony Foale. Albert Bold of Bold Precision fabricated the front swingarm.

eCycle Inc.,
MachineArt, machineart.com

Inside the eCycle hybrid motorcycle:
Though earlier prototypes used parallel powertrains, the latest effort is a series hybrid with three special aspects: Battery-pack voltage has been significantly reduced; the auxiliary battery supporting lights, horn, and other 12-V accessories can be switched into the main battery pack for higher power/speed; and the SolidSlot CMG (commutated motor/generator) coupled to the engine changes in speed and, therefore, voltage when the auxiliary battery is put in series with the main battery.

Overall, the platform works like a fully electric motorcycle, but with a high-efficiency, high-power-density gen-set replacing a significant portion of the battery pack. The bike converts to a plug-in hybrid by simply adding an ac-powered battery charger. The appropriate battery pack gives the bike the desired commuting range.

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