High gas prices have sent consumers scrambling to smaller cars, mass transit and even scooters. Another alternative: electric bikes.But can a hybrid-electric bicycle really take theplace of a car? To find out, I tested an Urban XU450 made by OHM CyclesLtd. It combines a commuter-style aluminum bike with a lithium-ionbattery and a small electric motor.Riders aren`t totally off the hook from labor - theystill have to pedal - but the battery and electric motor lend a handwhen covering long distances and steep hills. {See the Man vs. Machine race.}Unlike a hybrid car, the XU450 allows the rider to choose how muchelectric power reaches the wheels. A small digital controller on thehandlebar lets riders choose from four levels of assistance, and athrottle provides a burst of power as long as the bike is alreadymoving.The BionX electric motor, located in the rear-wheelhub, has a sensor that measures torque on the bike chain. It uses thatinformation to provide electric power that is proportional to how harda rider pedals, according to Michael DeVisser, president and founder ofOHM Cycles {www.ohmcycles.com}. It even compensates if one of the rider`s legs is pedaling more strongly than the other.The electric motor puts out 250 watts of steady powerand 450 watts of peak power, equivalent to the power that a human canput to the pedals. On the least-powerful setting, the electric motorprovides a boost equivalent to 25% of the rider`s output; the topsetting shells out a 200% boost, according to Mr. DeVisser.On the street, the hybrid powertrain works well onmild inclines and flat terrain. When pedaling around a hilly suburbanneighborhood with the assist set to the max, it feels like someone ispushing the back of the bike.Mr. DeVisser says the motor provides "a natural,smooth feeling" when biking. That`s accurate. But on a steep grade, theelectric motor felt overwhelmed. I had to pedal about as hard as Iwould on a regular bicycle, and I felt dragged down by theless-than-ideal gearing and the XU450`s 50-pound weight.Charging the battery is about as simple charging acellphone. The lunchbox-sized battery case can be removed from the bikeand the similar-sized charger plugs into a standard wall socket. Mr.DeVisser says the battery can be charged in three to four hours andlasts about 70 miles on a charge. At the end of my 3-5 mile rides, thebattery indicator showed half a charge remaining. The XU450 has theleast powerful battery OHM offers and Mr. DeVisser says the companyplans to offer more battery options and a smaller case.The bike also can be charged when in motion. TheXU450`s coolest feature is the regenerative brake system, which helpsrecharge the battery when the rider applies the brakes - a featurefound in a Toyota Prius. There are also disc brakes - high-tech for abicycle - when more stopping power is needed.The electronic controller on the OHM can also usehuman pedal power {or momentum from a hill} to charge the battery. Thiswas particularly useful on a steep downhill because the regenerationcan slow the bike without applying the disc brakes.
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