In the theoretical electric bike we considered up above, we had the dynamo/motor driving the back wheel directly, simply by pressing on the tire. Most electric bikes work a different way. They have compact electric motors built into the hub of the back or front wheel (or mounted in the center of the bike and connected to the pedal sprocket). Take a look at the hub of an electric bike and probably you'll see it's much fatter and bulkier than on a normal bike. You can read more about how these motors work in our main article about hub motors.
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,[72] and reaching an estimated fleet of 120 million e-bikes in early 2010.[2][73] 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.[72] Users began replacing traditional bicycles and motorcycles and e-bike became an alternative to commuting by car.[2] Nevertheless, road safety concerns continue as around 2,500 e-bike related deaths were registered in 2007.[73] 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.[72][73]

I bought the 52v 13ah for my 1000w BBSHD build and it is working great. My bike tears it up pretty good with this battery pack. Hopefully I don't run into any problems but so far so good. One thing I learned the hard way - if you use a 52v pack with the 1000w bbshd your battery meter will no longer be accurate. That was one tough ride home with my heavy fat bike!
There are individuals who claim to have lost considerable amounts of weight by using an electric bike.[62] A recent prospective cohort study however found that people using e-bikes have a higher BMI.[63] By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able.[64] This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer. [1]