Electric Bicycles Calories or Coulombs?

Contributed by Harv

Motors on bicycles have been around almost as long as there have been bicycles. And just as long as there have been automobiles. Early motor-driven bicycles evolved, of course, into motorcycles. Here we are today in a motor-fuel crisis and motors are again being applied to the basic pedal-bike. OK, so we are all of the muscle-powered bicycle persuasion, right? But let’s take a look at the state of the art of modern electric motor driven bicycles just so we know what’s going on.

What is the appeal of such a device? Well, sometimes (and for some riders) a bit of assistance would be nice. Long distances, heavy loads, and hills are a few of the reasons. Or maybe working up a sweat is undesirable. So we attach a simple electric motor to the rear wheel, and hang a large enough battery somewhere on the bike to make it practical. Then we wire up an electronic control and away we go. After a while the battery runs down and we need to charge it. That’s all there is to it.

There are some drawbacks. Electric bikes have limited range, limited speed, and you have to replace the batteries fairly often. Most modern e-bikes are powered by plain ol’ lead acid batteries that are not designed to be deep-cycled. Deep cycling means running the battery down to a low state of charge and then re-charging to full capacity. Better batteries that are designed for deep cycling are more expensive. Fuel cells for e-bikes are a ways off.

Legally, e-bikes have a large advantage over other motorized transport. No license, registration or insurance is required if the motor power is below 1000 watts. Top speed must be kept below 20 mph, even when pedalled. A bicycle helmet must be worn and the rider must be at least 16 years old. Riding in bike lanes is OK, and bike path riding may be permitted under some circumstances, although the statute, California VC 406(b), is not crystal clear on this. Any bicycle powered by a motor that is of the internal combusion variety is considered a motorcycle for purposes of licensing and insurance and is of no interest in this discussion.

Several e-bikes meeting these technical requirements are currently being manufactured. Overall, most resemble mountain bikes with a lumpy rear axle (the motor) and a heavy package on the rear rack (the battery).  Other than these anomalies, its a regular mountain bike and shares the same wheels, seat, frame, fork, pedals, crank, gears, etc. This makes is easy to get replacement parts for and perform routine maintenance on the ‘cycle’ parts. All-up weight runs between 50 and 75 pounds, so pedalling with a dead battery is possible, but a bit more work than you might want to do. At least you won’t get completely stuck if you run low on battery charge.

Briefly, the e-bike operating system is typically this: electric energy stored in a pack of lead-acid batteries is fed via an electronic controller, modulated by a twist-grip or thumb-trigger, to a brushless DC motor directly driving the rear wheel.  A normal pedal-crank-chain-sprocket system is also in place and can supplement the electric power to drive the bicycle, increasing its range.

Most e-bikes are made, like their pedal-only counterparts, in China or Taiwan. Several good offerings are available locally. Prices start at about $300 and go up from there. Hot rod e-bikes are available with quite high top speeds and increased range. These are not legal for use without an M2 (small motorcycle) or better endorsement on your driver’s license and require registration and insurance. Note that the CVC statute quoted above is for *bicycles* not electric scooters. Scooters are much more regulated and are not of interest here. The liberal e-bike laws were passed specifically to encourage non-polluting alternative transportation, but are tightly written to include only basic pedal-bikes equipped with a small electric motor and a battery pack.

So let’s take a look at what is available out there. Relatively new on the market is the EV Sunny Bicycle that has solar panels built into the wheels. While it cannot operate continuously on solar energy, the battery will recharge from the solar cells. Price is $1295 for the complete bike, less for the kit to convert your bike.

For those interested in the bare minimum expenditure to enter the market, the Mongoose ($349) has a 24 volt 450 watt motor with a claimed range of 18 to 25 miles depending on the degree of pedal assistance. Note that when 24 volts is specified, that means it has a two 12 volt battery pack which would be less expensive to replace than a 36 volt battery pack consisting of three 12 volt batteries. On this bike, the battery pack is located behind the seat tube and in front of the rear wheel. Most other battery packs are located in the main triangle.


An established e-bike maker, Currie, offers a 24 volt 450 watt, 18 mph bike with a range of up to 20 miles for $699.

Expensive at $2900, the WaveCrest M750 (pictured at the top of the article) has a 36 volt 750 watt motor and a range of 20 miles at 20 mph. Both battery and motor are located in the bike’s wheel hubs, which give it a clunky look, not to mention the added un-sprung weight. I test rode one of these at last year’s Earth Day at the Audubon Center in Deb’s Park and was impressed with the torque (it does wheelies uphill) but not too impressed with the design. There is a more powerful “X” version of this bike but it is beyond the legal limits for license-free operation.

A step-through design is used in the $680 Urban Mover which has a 36 volt 200 watt motor. Rated range is 12 to 18 miles.

Giant makes the Lite which is available as a step-thru or sloping top tube model.  Price is about $1000, motor is 24 volt 400 watt, rated speed is 17 mph, and the drive train uses an 8 speed hub.

Lastly, and my personal pick, is the $750 Lashout with a 600 watt, 24 volt motor, full suspension and standard mountain bike design. Rated top speed is 18 mph with a range of 12 miles (no pedalling) to 25 miles (constant pedal assist).

 In summary, beware of high-spec electric bikes which may fall outside of the legal definition of an e-bicycle. Look for standard bicycle parts such as wheels and tires, handlebars, cranks, chain rings and cassettes. Stay with 24 volt battery packs for cheap replacements. Check for control system operation: Must bike be pedalled for power assist to work? Can bike be ridden with battery power only? Is battery pack quick-detachable? Are standard batteries used? (Usually, two 12 amp-hour motorcycle lead-acid batteries will make up the pack. These are cheap and readily available).

All of the above said, a conventional pedal-only bike is still the best bet. No speed limits, no charging time necessary, no batteries to replace, no  electronics to burn out, no risk of getting stranded (due to dead battery or control system). Not to mention the fun, freedom, and health benefits.