China has experienced an explosive growth of sales of non-assisted e-bikes including scooter type, with annual sales jumping from 56,000 units in 1998 to over 21 million in 2008, and reaching an estimated fleet of 120 million e-bikes in early 2010. This boom was triggered by Chinese local governments' efforts to restrict motorcycles in city centers to avoid traffic disruption and accidents. By late 2009 motorcycles are banned or restricted in over ninety major Chinese cities. Users began replacing traditional bicycles and motorcycles and e-bike became an alternative to commuting by car. Nevertheless, road safety concerns continue as around 2,500 e-bike related deaths were registered in 2007. By late 2009 ten cities had also banned or imposed restrictions on e-bikes on the same grounds as motorcycles. Among these cities were Guangzhou, Shenzhen, Changsha, Foshan, Changzhou, and Dongguang.
The size, when folded, lands in the middle of the field, narrow enough to fit through subway turnstiles and compact enough to avoid getting too many annoyed looks on an elevator. Its 28-pound weight is average (news flash: none of these bikes are really very light), and this model is rated for riders up to 230 pounds. The handlebars both pivot and telescope to accommodate riders of different heights (from 4-foot-9 to 6-foot-3) or riders who simply prefer a more upright position.
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.
If you are like a lot of New Yorkers, you may have trouble finding a safe and dry place to put your bike at home. Your tiny apartment refuses to budge another inch, and the street seems to be the place bikes get left to find new owners. You may also want to ride to work, but parking is hard to find. If you try to take your bike into your building, the concierge looks at your bike as if it was a giant wheeled rat and refuses to let you onto the elevator. You may also long to take your bike along on a trip that requires transit, but cannot because of rush hour restrictions or outright bans on bicycles on trains or buses. The solution you are looking for might be a folding bike.
This eco-friendly bike is completely electric and emissions-free. If you care about the environment but still want to enjoy easy commuting, consider this bike. The Swagatron SwagCycle uses a 36V battery and a 250W motor that allow you to go up to 10mph. The battery takes about 2.5 hours to charge, and you can go up to 10 miles before having to recharge it. The frame is made of aerospace grade aluminum and folds into a compact size. It’s ideal if you struggle with storage space since it can fit pretty much anywhere. The handlebar display shows you the battery life and allows you to honk the horn, turn on the headlight, and brake and accelerate. One of the coolest things about this bike is that it features a USB charging port for charging all your gadgets and devices. However, note that this bike doesn’t have any pedal assist mode. Also, SwagCycle comes with a battery charger and user instructions that help you with the assembly.
Not only will you struggle to get the B.O.B to the top of steep hills, it does not have safe braking power for the way down and is not stable at higher speeds. The B.O.B comes complete with fenders, a chain guard, and a kickstand, making it ready for you to commute in any weather. Where it really shines is the ease that it can be folded, as well as the light weight.
But in the moment, the Oyama didn’t seem to care what it was supposed to be designed for, it only cared about moving forward. And forward it went. Over the dirt, over the stumps, up the hills and through the gravel. It overcame nearly every obstacle and terrain I could find until I finally had to help lift it over a fallen log blocking the trail and under a vine waiting to clothesline me. Perhaps I could have hopped the log if I had really tried, but by that point I figured the Oyama had made its point.
Want to read about more folding bikes? A buyer's guide to a wider selection of folding bikes appeared in A2B Magazine and is available here. Another more detailed buyer's guide is published by the Folding Society and is available here. The Folding Society is probably the single most detailed Web site on the subject of folding bikes and should be able to give you the answer to almost any question. Also take a look at
Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.
The suspension works, but there isn’t any true dampening. That means you’re just riding around on springs. On a real full suspension e-bike (i.e. a few thousand dollars) you get actual oil-dampened shocks. Those absorb bumps and dampen the shock. With springs, the bike bounces a few times after bumps, with the energy dissipating through the spring stretching and compressing.