In a friction drive motor, a small, solid wheel rotates against the side of the tire in order to drive it. The first motorcycles used the same concept, with a motor mounted above the front wheel. The problem is that the drive rubs at the side of the tire. It's inefficient, and it quickly wears the sidewall away. Tires need to be replaced every couple hundred miles. For this reason, you'll seldom see electric bikes with this type of drive anymore.
Built around a heavy-duty alloy frame, the GSD eschews many of the traits of other cargo bikes: long wheelbases, bigger wheels, and especially, an unwieldy ride. Yet it boasts an extensive capacity, nimble handling—even fully loaded, thanks to a short wheelbase and 20-inch wheels—and enduring range in a package not much bigger than most non-cargo e-bikes. The stout frame holds a 250-watt Bosch motor that gives up to 275 percent of your power back to the pedals and reaches 20 mph. The GSD has room for two battery packs, extending the batteries’ combined range to a claimed 150 miles and making the Tern one of the longest-lasting e-bikes on the market. A laundry list of accessories and a (claimed) 396-pound carrying capacity round out the GSD’s status as an epic day-tripper.
Photo: This typical electric bicycle, a Sanyo Eneloop (now discontinued), had a range of about 30–55 km (17–35 miles) and a top speed of around 24 km/h (15 mph). Note the 250-watt hub motor on the front wheel and the 5.7Ah lithium-ion battery pack (black, marked "Sanyo," just in front of the back wheel). Picture by kind permission and courtesy of Richard Masoner, originally published on Flickr under a Creative Commons (CC BY-SA 2.0) licence.
The company was founded in 2009 by Tora Harris who graduated from Princeton University with a degree in Mechanical and Aerospace Engineering. While at Princeton, Harris ran track and became a 2-time winner of the NCAA Championship in the High Jump and set several Ivy League track records in the process. Harris went on to win 2 USA National Outdoor Championship Titles and competed in the 2004 Athens Olympic Games.
The Class 3 Aventon Pace 500 urban e-bike has five levels of pedal assist and tops out at 28 mph. But the Pace has something not found on a lot of modern e-bikes. In addition to pedal power, it also has a throttle—in the case of the Pace, a small thumb paddle on the left side of the handlebar next to the control unit that holds at a steady 20 mph, no pedaling required. The bike itself has an aluminum frame, a swept-back handlebar, ergo grips, a sturdy kickstand, hydraulic disc brakes, 8-speed Shimano Altus shifting and gearing, 27.5x2.2-inch Kenda e-bike-rated tires, a saddle the size of Texas, and good ol’ classic city/commuter-bike geometry. It doesn’t come equipped with fenders or a rear rack, but you can add them. Power comes in the form of a 500-watt rear-hub motor, a semi-integrated battery on the down tube (with a range of up to 50 miles), and a backlit display unit mounted on the stem.
Oregon Law (ORS 801.258]) defines an electric assisted bicycle as an electric motor-driven vehicle equipped with operable pedals, a seat or saddle for the rider, no more than three wheels in contact during travel. In addition, the vehicle must be equipped with an electric motor that is capable of applying a power output of no greater than 1,000 watts, and that is incapable of propelling the vehicle at a speed greater than 20 miles per hour on level ground.[124]
On October 5, 2009, the Government of Ontario brought in laws regulating electric bikes in the province. E-bikes, which can reach a speed of 32 kilometres per hour, are allowed to share the road with cars, pedestrians and other traffic throughout the province. The new rules limit the maximum weight of an e-bike to 120 kilograms, require a maximum braking distance of nine metres and prohibit any modifications to the bike's motor that would create speeds greater than 32 kilometres per hour. Also, riders must be at least 16 years of age, wear approved bicycle or motorcycle helmets and follow the same traffic laws as bicyclists. Municipalities are also specifically permitted by the legislation to restrict where e-bikes may be used on their streets, bike lanes and trails, as well as restricting certain types of e-bike (e.g. banning "scooter-style" e-bikes from bicycle trails). E-bikes are not permitted on 400-series highways, expressways or other areas where bicycles are not allowed. Riding an e-bike under the age of 16 or riding an e-bike without an approved helmet are new offences in the legislation, carrying fines of between $60 and $500. E-bike riders are subject to the same penalties as other cyclists for all other traffic offences.
The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex.
It's a solid e-bike, but it's also very heavy one for a folding bike. I found it difficult carry when the bike is folded as the carrying handle is useless, and the center of gravity is towards to the rear wheel so one has to find a place in the rear of the bike to pick it up. Even when the bike is folded, it's bulky and heavy, It's difficult to walk with it while carrying it. It's easy to hurt one's back if he or she is not careful. I would not recommend carrying this bike up or down stairways.
Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% of the world's bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined due to the increasing affordability of cars and motorcycles.[102] One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the lower cost of labor in China.[103]
At the moment this battery is in stock but for local pickup orders only as we are going through the certification testing required for shipping. We've been keeping the 21700 cell offerings on our radar as they start to catch up with the performance specs of the more mature 18650 series and this year it looks like they are finally making the grade. Expect more from us as the year goes on. 
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque, and others, like Bosch’s Active Line, are nearly silent. But, generally, all four make good options. Look for motor output (in torque), which will give you an idea of total power. Just like car engines, more torque equals more power off the line and more boost to your pedaling. But watt hours (Wh) is perhaps a more important figure to use—it takes into account battery output and life to give a more accurate reflection of power (higher Wh equals bigger range).
Bicycle suspensions are used primarily on mountain bicycles, but are also common on hybrid bicycles, as they can help deal with problematic vibration from poor surfaces. Suspension is especially important on recumbent bicycles, since while an upright bicycle rider can stand on the pedals to achieve some of the benefits of suspension, a recumbent rider cannot.

What's the Centros like? Big and heavy, but with enough power to overcome that, it really reminded me of a more upmarket Volt Pulse. You do tend to find that the weightier e-bikes give more of a feeling of speed, even though you're only doing 20mph or so at the absolute most (only up to 15mph with electrical assistance so you'll need leg muscles or a downward incline to get to that outlandish velocity).
Photo: Could solar power be the future of electric bicycles? The large solar panel mounted over the back wheel of this experimental bike powers an electric motor connected by a chain drive to the back wheel, helping the rider when he doesn't feel like pedaling. Using clean, green solar power would remove the problem of having to charge electric bikes with electricity generated from fossil fuels—and help to extend their range significantly. Photo by Warren Gretz courtesy of US DOE/NREL.

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.[43]
Even the humble bicycle hasn't escaped the clutches of modern technology. A whole herd of new e-bikes with electric motors are taking to our cities' streets. Adding a motor to a standard cycle does ramp up the price significantly, but it takes much of the effort out of cycling, making your commute to the office a sweat-free experience and allowing you to sit back and enjoy your suburban cruise.
The first mechanically-propelled, two-wheeled vehicle may have been built by Kirkpatrick MacMillan, a Scottish blacksmith, in 1839, although the claim is often disputed.[20] He is also associated with the first recorded instance of a cycling traffic offense, when a Glasgow newspaper in 1842 reported an accident in which an anonymous "gentleman from Dumfries-shire... bestride a velocipede... of ingenious design" knocked over a little girl in Glasgow and was fined five shillings.[21]
Being member of European Economic Area (EEA), Norway implemented the European Union directive 2002/24/EC. This directive defined legal ebikes for all EU and EEA countries to "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.” The definition became part of Norwegian vehicle legislation[17] in 2003. A more detailed specification will become effective when the new European ebike product safety standard EN 15194 is published in 2009.
We need to support and put our purchasing power behind ebikes sold in the U.S. that are trying to comply with the California rules which allow 500w and 750w nominal motors and establish 3 classes. If these bikes can create a big enough footprint in the market then future U.S. bike rules may universally adopt these standards. It is better than engaging in regulation showdowns without any standardized and unified proposal on the part of the Electric Bike Community.

It’s unlikely the Instagram generation ever thought there would be an eBike built with them in mind. Stereotypes of old people riding their e-assisted bikes with cumbersome batteries and questionable frames. Then Lithium Cycles and the Super 73 turned up! Across the last few months, social media has been bustling with talk, influencers, Will Smith … Continue reading Lithium Cycles Super 73: Coming Soon
Biking is awesome, but biking uphill is not. Commuting by bike is environmentally friendly, fun and good for your health, but presenting your sweaty self to your office coworkers in not fun at all. Fortunately, there is a solution! Electric bicycles offer the same great benefits as traditional bicycles including cost savings, health improving, plus some additional advantages like efficiency in climbing hills, less stress on knees and joints, which is convenient for people of all ages and health.