In Israel, persons above 16 years old are allowed to use pedal-assisted bicycle with power of up to 250W and speed limit of 25 km/hour. The bicycle must satisfy the European Standard EN15194 and be approved by the Standards Institution of Israel. A new law, effective January 10, 2019, states that riders under 18 who have no automobile license will need a special permit.   Otherwise, no license or insurance is required. Other motorized bicycles are considered to be motorcycles and should be licensed and insured as such. The maximum weight of the e-bike itself cannot exceed 30 kg.
Hub motors are sold as either geared or direct drive: Geared hubs are preferred for hill climbing ability and zero drag when coasting, while DD hubs are more durable and suitable for high speed. Extreme hill climbing and high torque applications (fatbikes, hauling cargo, popping wheelies) usually requires a mid drive, which is covered in the motor section below. Ebike battery packs from the listed suppliers are generally compatible with kits from any supplier, at worst you may need a different connector, which can be easily replaced. You probably want a battery pack that is 36, 48, or 52 volts, depending on whether you prefer lower price and longer range or a higher topspeed. DIY lipo battery packs can be built cheaply but doing so can be a fire hazard so actual packs are recommended. All hub motors above 24 V should be installed with torque arms for safety.
You turn it on by pressing the green button on the battery once for low power and twice for high, although to be honest, there is not a lot of difference between them. After that, you just pedal. There are no gears, no chain to muck up your trousers (a motorbike-style carbon fibre belt is used instead) and not that much difference in feeling compared to riding a normal bike.
Whether squeezing onto the 4 train or pedaling through Lower Manhattan, I notice a few curious glances at the bike with the big battery in the center of the frame. This is not surprising; e-bikes are huge practically everywhere but the US. According to the latest figures from the Confederation of the European Bicycle Industry, e-bike growth in the UK is up from 40,000 units in 2016 to 63,000 in 2017.
But in Great Britain, the European Union definition is applicable, and the tighter restrictions of the Electrically Assisted Pedal Cycle Regulations 1983 (including a 200 kg weight limit on solo bicycles) were removed on 6 April 2015 by the Electrically Assisted Pedal Cycles (Amendment) Regulations 2015. Riders must be at least 14 years of age, but no driving licence is required.
To qualify as an electric-assisted bicycle under state law they need to have a seat and fully operable pedals for human propulsion, meet federal motor vehicle safety standards, an electric motor that has a power output of not more than 1,000 watts, maximum speed of not more than 20 mph (electric motor and human power combined), disengages or ceases to function when the vehicle’s brakes are applied, two or three wheels