In a parallel hybrid motorized bicycle, such as the aforementioned 1897 invention by Hosea W. Libbey, human and motor inputs are mechanically coupled either in the bottom bracket, the rear wheel, or the front wheel, whereas in a (mechanical) series hybrid cycle, the human and motor inputs are coupled through differential gearing. In an (electronic) series hybrid cycle, human power is converted into electricity and is fed directly into the motor and mostly additional electricity is supplied from a battery.
For those looking to hit the trails instead of the pavement, Yamaha has you covered with their new YDX-TORC electric-assist bicycle, which is powered by a souped-up version of their mid drive known as the Yamaha PW-X center drive motor system, which the company claims offers the extra power needed for more adventure and exploration on the trails, including a fifth power assist setting. As a more powerful e-bike, the YDX-TORC also demands a higher price of $3,499.
Probably the most important thing to consider when researching the best electric touring bike for you is how far you need your bike to take you every day. Be realistic about this. If you purchase a lower end electric bike, don’t be surprised when it only takes you half as far as you want to go. Think about whether or not there are going to be opportunities to charge your battery in the middle of your daily riding. If not, it might be a good idea to buy an extra battery.
After you decide which style of e-bike you want, consider the class. In the US, there are three classes defined by the type of assist and how fast the motor will propel you. Most electric bikes sold are class 1 or 3. Class 1 bikes have a motor (max 750w) that assists while you're pedaling, up to 20 mph. Class 3, also known as “speed pedelec” can also have up to a 750w motor, but it can assist you up to 28mph. Both of those are allowed in most states and cities without license. Class 2 have throttles that don't require you to pedal to get a boost. They're allowed on most streets, bike lanes, and paths, but less popular than the other classes and not covered much here (because we still love to pedal and the greater distances pedal assist bikes can cover).