Summer is finally here and for many, breaking out the summer clothes is motivation enough to start exercising. One traditionally popular method, bicycling, promises even more than a good work out, it's fun and can get you where you're going in a hurry.
A growing number of American consumers are getting a "charge" out of electric bicycles — they look and feel like traditional bikes, but with a battery-powered assist.
Ironically, what's thought to be the first electric bicycle debuted more than a century ago in Europe. Over the years, inventors have tinkered with different electric drive systems, but modern electric bike history didn't actually begin until 1994 when Yamaha introduced its PAS (powerassisted system) bikes in Japan. A U.S. company, Zapworld.com in Sebastopol, Calif., entered the market a few months later. Since then, many European, Asian, and American companies have jumped on the e-bike bandwagon. And, the popularity of these "turbo-charged" bicycles is increasing not only for well-being and recreational purposes, but for day-today transportation.
MORE POWER TO YOU
Electric bicycles essentially assist riders in pedaling. These bikes, according to consultant Ed Benjamin of CycleElectric International Consulting Group, are available in two forms: E-bikes, which are controlled with only a throttle, or pedelecs (which stands for pedal electric), human/electric hybrids where motor speed synchronizes to pedaling speed. Both types are popular but pedelecs are the most common worldwide, says Benjamin.
With just a flick of a switch or twist of a throttle, electric bikes take off with a silent burst of power. Working together with pedaling, electric bikes can conquer hills easily and distances of up to 20 miles on a single battery charge, and at speeds between 15 and 20 mph.
Today's electric bikes come in many styles and drive configurations but are all similar in that they use a battery to provide turning power to an axle. Sealed lead-acid batteries are the most commonly used and are the least expensive at about $22 for each battery, but they also weigh the most at around 20 lb. Other batteries, including nickel cadmium and nickel-metal hydride, are also used and can travel greater distances on a single charge, but cost substantially more. Recharging is said to be easy and inexpensive, though, by plugging chargers into any standard 110-Vac outlet. It takes just a few hours and costs only a few cents per charge.
Several drive systems are on the market. One of the simplest mechanisms is a friction drive which depends on the friction between a roller and the tire. When the motor is turned on, the rider's weight, the grade, and wind resistance basically control speed.
Direct drives, on the other hand, typically connect to a rear axle sprocket via a chain or may be connected to the pedal sprocket. Hub motors, another form of direct drive, attach to front or rear wheel hubs. With the German-produced Heinzmann hub wheel motor, for example, riders have two options for electric-assist control: An automatic sensor version adjusts the power to the effort the rider puts out, while a twist grip version lets riders quickly build power, even without pedaling.
Today's electric bikes are a design balance, according to Benjamin. Deciding what that balance should be for consumers is a designer's trickiest task. For instance, the least expensive bikes are also limited in battery range and speed, while the best performers require larger, more advanced batteries, but at higher prices. Says Benjamin, designers are striving for a 20-mph bike that will travel 20 miles, weigh less than 60 lb, and cost about $1,000.
MEET THE MAKERS
Though it took awhile for electric bicycles to gain a foothold in the U.S., a handful of manufacturers are selling now with others ramping up for production as sales grow. Here's a few key players in the market.
Zapworld.com, recognized as the electric bike pioneer in the U.S., introduced a power system in 1994. At that time, there really wasn't a market for electric bikes outside of Japan, according to Alex Campbell, spokesman for Zapworld.com. In 1996 the company received the first of many patents for its electric motor system. The ZAP (which stands for zero air pollution) power system includes two permanent-magnet, brushed dc motors, a battery and battery containment system, and a two-speed controller and throttle. ZAP uses a friction drive and rollers to turn the back tire. The rollers are each made of an aluminum shaft enclosed in a steel sleeve. A heavy diamond knurl in the sleeve keeps the tire from slipping when wet. The rollers slide over two motor shafts which supply the power.
Zapworld Models use 300-W, 12-V aftermarket motors, which run for about an hour without recharge, providing a range of 5 to 20 miles. A switch on the handlebar activates the motor, boosting pedaling power so riders speed up with less effort. A charging stand is also offered in case riders want to charge the battery while using the bike as a stationary exercise machine.
ZAP e-bike kits can be fitted on existing traditional bicycles and a variety of mounts are available. For freewheeling, the power system can be disengaged so it doesn't drag.
Th!nk Mobility, a subsidiary of Ford Motor Co., is in the electric bike business with a number of products, each offering power-assisted commuting at the flick of a switch. Th!nk is set to launch two products this summer: The Traveler, a compact model with a foldable frame, and the rigid-framed Fun. Both bikes let riders use their own leg power or, by flicking a switch on the right handlebar and twisting the Rheostat throttle in the grip, power up using the electric motor. Both the Fun's 24-V, 400-W motor and the Traveler's 24-V, 250-W motor are powered by a lead-acid battery pack stored under the seat. Charging takes just four hours from a standard home outlet. A direct-current charger is also available for recharging from 12-V power sources, but this method takes about eight hours to complete. The standard drive system is a single-speed, direct-link transmission located in the crankshaft area, but a two-speed model is also available. The Fun can go 30 miles before recharging while the Traveler's range is 18 to 20 miles. Top speed for both is 16 mph.
Another player is Yamaha Motor Co., designer of the PAS for pedelecs. PAS includes a rechargeable battery, microprocessor controller, motor, and drive unit to transmit energy to the rear wheel. A sensor in the drive unit continually feeds pedaling force and vehicle speed data to the microprocessor. The microprocessor then calculates how much assistant power is needed and sends signals to the motor to generate that power. These steps are repeated every 1 /100th of a second. Big in the U.S. following its introduction in Europe and Asia is the LaFree produced by Giant Bicycle Inc., Rancho Dominguez, Calif. The LaFree boasts Giant's patented Variable Power Control (VPC) system in which bikers simply twist a handle grip according to how much boost they want. This is said to extend the 24-V battery's power, giving it a maximum range of 24 miles at a speed of 17 mph.
"VPC is a hybrid between pedal assist and 'twist and go' bikes," says Fred Teeman, vice president of Giant's Electric Bicycle Div. "Twisting the handlebar throttle overrides the pedal assist logic, allowing bikers to control the motor with their hand, but still rotating the pedals. You don't have to push the pedals but you have to rotate them. If you are lazy or tired that day, you can use VPC but if you want to get exercise and more distance you can use what we call power-assist pedaling (PAP)."
PAP works by sensing pedal pressure — the more pressure put on the pedal the more the motor assists. A self-diagnostic system lets bikers test brakes, speed sensors, batteries, and pedal torque sensors by simply using a paper clip for a tool. Batteries take about 4 hr to recharge on a full dis-charge. The LaFree uses a 400-W, 24-V motor to provide power at the crank. Applying the brakes automatically disengages the power-assist motor.
Also in California, Currie Technologies Inc., Van Nuys, developed an electric propulsion system for its own line of electric bikes that can be retrofitted on ordinary bicycles. The patented direct-drive power system, which company founder Dr. Malcolm Currie calls the "unitary propulsion system," has a brushless motor that fits on the rear wheel's axle. The motor drives a chain connected to a sprocket on the axle. The whole system is sealed and waterproof. "The unique feature of our system, on which we have several patents," explains Currie, "is that it is not part of the bicycle frame. The rear wheel can be dropped down to fix flats, and the system always stays in perfect alignment, even with high shocks."
The fact that Currie's system is simple in design and function has made it easy to adapt to regular bicycles. In fact, Schwinn Cycling and Fitness, Boulder, Colo., licensed Currie's system to power its electric bikes. Schwinn characterizes Currie's system as lightweight and virtually frictionless when disengaged, saying that the system rides and handles like a conventional bike, operates well in bad weather, is easy to carry around, and can be repaired in traditional bike shops.
Currie's system has a one-way clutch allowing bikers to coast and pedal with the motor off and without dragging the drive mechanism. A thermal control automatically cuts out the motor before it can overheat and starts it again after a brief cool-down period. The brushless motor, which Currie says is rare in electric bicycles, doesn't wear as typical brush motors do. The sealed lead-acid battery provides power over a 20-mile range and runs up to 18 mph. And, says Currie, on steep hills the system delivers high torque for maximum power-assist performance.
With a great deal of fanfare, former Chrysler chairman Lee Iacocca entered the electric bike market in 1997, forming E.V. Global Motors to re-search, develop, and commercialize light electric vehicles. "I've decided to come clean," he says. "I plan to provide Americans a range of new and exciting light electric vehicles, that are quiet, clean, safe, and fun. It's my way of helping clean up the world a bit ." The first of these to reach fruition from the Los Angeles-based company was the stylish E-Bike. A flick of the thumb-operated throttle turns this standard bicycle into a self-propelled vehicle courtesy of a 400-W hubmounted brush motor.
Dual 24-V lead-acid batteries power the E-Bike at about 14 mph over a 20-mile range — longer when assisted by pedal power — and can be removed for remote charging. An on-board charging system works off a 110-V household outlet, and is fully recharged in just 4 hr.
These motorized bikes share some similarities with automobiles. E-Bikes have cruise control, a front suspension system, an optional front disc brake, and halogen head and taillights. An economy battery-saving switch on the left handlebar saves power when cruising. Riders needn't worry about dead batteries though, because three indicator windows on the right handlebar tell if they are full, half-full, or empty. E-Bikes can also be pedaled just like traditional bicycles.
Currently, three E-Bikes are available. The Touring Model, designed especially for longer rides, features a wide gel saddle, suspension seat post, and soft luggage areas. The practical Comfort Model has additional suspension that handles bumps and potholes, and the Standard Model, which sells for just under $1,000, is built for convenience and trouble-free operation. Other electric vehicle designs with the same power system but more creature comforts are soon to come. Instead of retailing through bicycle dealers, the E-Bike will be sold through auto deal-erships, but riders don't need to have a driver's license to operate it.
In fact, most electric bike makers share this common goal: To have electric bikes treated as conventional bicycles on roads and bike paths, without requiring vehicle registration or a driver's license.
Smooth-running e-bikes have brushless motors to thank
No stranger to electronic motors and drives, Koll-morgen Corp., Waltham, Mass., will supply custom dc brushless electric motors for EV Global Motor's E-Bikes and Currie Technologies' U.S. Pro Drive electric bikes.
"These brushless motors bring high efficiencies to this kind of application," says Willy Verbrugghe, president of Kollmorgen's Industrial and Commercial Group. "In the past, the motors had to be so large that it made the bikes impractical. We expect this market to grow very quickly over the next few years both in the U.S. and overseas."
Motors without "brushes" or mechanical contacts are said to eliminate friction and reduce wear, this keeps the system running longer on a single battery charge. In fact, the motors offer more than 90% efficiency, generate speeds to 18 mph, and travel up to 20 miles on a 3-hr charge.
With Currie's design, the direct-drive motor attaches to a drive plate on the rear wheel of the bike. The system comes in two or three-wheel models with two speeds, or can be ordered as a conversion kit for any 26-in. bike. The E-Bike, on the other hand, integrates the motor as part of the rear hub and ranges in price from $1,000 to $1,395.