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.
Maybe the most confusing legal issue facing e-bike riders today is the difference between a bike lane and bike path. A bike lane is a marked section of roadway shared with motor vehicles. Bike paths pretty much universally prohibit the use of motorized vehicles. Still, you will need to research your area. As an example: “A path near our office specifically says “no motorized bicycles.” Yet, when we tracked down an employee who claimed to work enforcement on the path, he said that our e-bike was allowed.”8
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.
Under the doctrine of One Country, Two Systems, Hong Kong has independent traffic law from mainland China. Electric bike are considered as motorcycles in Hong Kong, and therefore needs type approval from the Transport Department as other automobiles. All electric bike availble in Hong Kong fail to meet the type approval requirement, and Transport Department has never granted any type approval for electric bike, making all electric bike effectively illegal in Hong Kong. Even if they got type approved, the driver would need a motorcycle driving license to ride. As a side note, Hong Kong doesn't have a moped vehicle class (and therefore moped driving license), and mopeds are consided as motorcycles too.
On the other hand, the battery doesn’t lock into the bike, which means you can’t just leave it on your bike when you park at the bike rack. Anyone could walk by and simply remove your battery. That seems like an oversight to me, though perhaps the designers assumed that such a small battery would just be easy to take with you. And it is. My wife could probably lose this battery in her purse.