"Medical Exemptions" are also a standard right in the State of Texas for motorcycles & even bicyclists. Through Texas's motorcycle helmet law (bicycle helmet laws from city ordinances), it is only required for those 21 years old or younger to wear a helmet. However, a medical exemption,[133][134][135][136][137] written by a certified licensed medical physician or licensed chiropractor, which exempts one from wearing a helmet, can be used for bicyclists if helmets are required.
Hmm, that’s unfortunate. I actually have a doctors note that I carry along which recommends the use of an assisted bicycle. I ride thoughtfully and have never been asked to show it. I cannot comment on the federal parks, perhaps they are not aware of the federal law classifying electric assist bikes that perform at or below 20 mph and 750 watts as bicycles. Having a note and this information would be a good response if you were questioned.
First off we want to apologize for the longer than normal response time and email backlog as much of our team was busy both in the preparation and attendance at the Taipei Cycle Show this past week. We'll be working hard to catch up on that in the coming days and thank your patience and understanding. To all the dealers, vendors, manufacturers, component partners, and general industry friends we met at the show, what a great time and we look forward to exciting pursuits ahead. 
Electric-assist and other "motorized bicycles"[86] do not need to be inspected, do not require a license, and do not require registration. The vehicle must meet all of the following criteria: a post mounted seat for each person it is designed to carry, two or three wheels which contact the ground, fully operative pedals, wheels at least 16 inches in diameter and a motor not capable of propelling the device at more than 20 mph on level ground. The driver does not need a license, but must be at least 16 years old. DC law prohibits motorized bicycles from traveling anywhere on the sidewalk or in the bike lanes. DC Regulation 18-1201.18 provides: "Except as otherwise permitted for a motor vehicle, no person shall operate a motorized bicycle on any sidewalk or any off-street bikepath or bicycle route within the District. This prohibition shall apply even though the motorized bicycle is being operated solely by human power." So, if cars are prohibited in a particular place, motor-assisted bikes are also prohibited.[87]
The battery is the pedelec’s power source. It supplies the motor with the electrical energy that is required to provide power assistance when cycling. So it is hardly surprising that there is frequent discussion and “talking shop” about the eBike’s battery in particular. What is the difference between batteries? How far can you go on a fully charged battery? What do you have to remember about storage? Thomas Raica, head of technical customer application, here provides information and advice.

When last checked, no E-bikes satisfied this requirement, so ebikes cannot be registered in New Jersey.[108] However, NJ Bill A2581, introduced March 22, 2010, would permit the use of low-speed electric bicycles upon the roadways and bicycle paths in NJ, where a low-speed electric bicycle is defined as a two-wheeled vehicle with fully operable pedals for human propulsion and an electric motor of less than 100 pounds and 750 watts, whose maximum speed on a paved level surface is less than 20 miles per hour.[109] The bill has been referred to the state's Assembly Transportation, Public Works and Independent Authorities Committee.[110]
The safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. As bicycles became safer and cheaper, more women had access to the personal freedom that bicycles embodied, and so the bicycle came to symbolize the New Woman of the late 19th century, especially in Britain and the United States.[8][73] The bicycle craze in the 1890s also led to a movement for so-called rational dress, which helped liberate women from corsets and ankle-length skirts and other restrictive garments, substituting the then-shocking bloomers.[8]
On February 4, 2014, SB997 was introduced by Senator Matt Smith, which seeks to amend PA Vehicle Code to include "Pedalcycle with Electric Assist". In a memo addressed to all senate members, Smith said the definition shall include "bicycles equipped with an electric motor not exceeding 750 watts, weighing not more than 100 pounds, are capable of a maximum speed of not more than 20 mph, and have operable pedals."[128][129] 

E-bikes can also provide a source of exercise for individuals who have trouble exercising for an extended time (due to injury or excessive weight, for example) as the bike can allow the rider to take short breaks from pedaling and also provide confidence to the rider that they'll be able to complete the selected path without becoming too fatigued[58] or without having forced their knee joints too hard (people who need to use their knee joints without wearing them out unnecessarily may in some electric bikes adjust the level of motor assistance according to the terrain). A University of Tennessee study provides evidence that energy expenditure (EE) and oxygen consumption (VO2) for e-bikes are 24% lower than that for conventional bicycles, and 64% lower than for walking. Further, the study notes that the difference between e-bikes and bicycles are most pronounced on the uphill segments.[59] Reaching VO2 Max, can really help your body as a whole[60]. Professor Janet Lord of Birmingham University in the UK published a study that looked at older cyclists, ““The study looked at muscle mass, blood cholesterol, their VO2 Max, lung function, and in many of those measures we found they didn’t age! No loss of muscle, their bones were a little thin (but nothing like the general population), their blood pressure didn’t go up.[61]
During the course of its evolution, the Specialized Levo has helped shape the world of eMTBing. When it was introduced, it set the benchmark in riding dynamics and integration. Now Specialized has completely redesigned the bike and put it on 29″ wheels. The integration has been improved yet again, the battery capacity has been increased and the handling has been refined. We were thrilled with our first test ride. Anyone looking for a new bike next year for maximum trail performance should definitely take a closer look at the new Levo! We’re already looking forward to our big group test of the best bikes of 2019 early next year.

Bicycles were introduced in the late 19th century in Europe, and by the early 21st century, more than 1 billion were in existence at a given time.[1][2][3] These numbers far exceed the number of cars, both in total and ranked by the number of individual models produced.[4][5][6] They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for use as children's toys, general fitness, military and police applications, courier services, bicycle racing and bicycle stunts.
In general, more expensive bikes are better. However, this is just a trend. E.g. the "Kassensturz" Consumer program from our state TV found in a 2012 study confined to an engineering school, that "Supermarket" bikes, e.g. the 1400 CHF (1200 Euro) "Leopard" bike from COOP did very well. Evaluation is "good" (almost the same as the three times more expensive 25km/h Stromer). They also pointed out a very bad model from a discounter. In other words, you can find good cheap models, but read the tests first.

eBikes are a key part of solution to reduce carbon emissions globally. The Zero-emission part of the eBike discussion is based on re-charging the battery on a daily basis from a Sustainable Electrical Source such as solar, wind, hydro, geo thermal, etc.  The fact is today part of the eBike Battery charge is coming from Power Plants that are running …

Oklahoma defines an Electric-Assisted Bicycle in 47 O.S. 1-104 [122] as "Two or three wheels; and Fully operative pedals for human propulsion and equipped with an electric motor with a power output not to exceed one thousand (1,000) watts, incapable of propelling the device at a speed of more than thirty (30) miles per hour on level ground, and incapable of further increasing the speed of the device when human power alone is used to propel the device at a speed of thirty (30) miles per hour or more. An electric-assisted bicycle shall meet the requirements of the Federal Motor Vehicle Safety Standards as set forth in federal regulations and shall operate in such a manner that the electric motor disengages or ceases to function when the brakes are applied."

Whether the terrain is flat or hilly impacts the distance you can travel, as does the weight of the bike, your own weight, the gearing available on the bike, and how much juice you give it. We suggest that a distance of 10 to 20 miles is a realistic expectation. Of course, if you're prepared to do at least some pedaling, you can extend that dramatically.

Brock had been running his esoteric shop on Cambie St. for over 30 years, pioneering the sale and production of recumbent bikes, tricycles, velomobiles, unicycles, and of course electric bicycles well before any of these things were popular. He was dabbling with early ebike conversions in the 1990's when we were still in grade school and has been for many years one of the few shops always willing to say yes to electric retrofits. We hope to still see him riding around streets of Vancouver in a white velomobile. 
The other shout-out goes to Paul Bogaert who decided to close the Bike Doctor after 27 years and instead cycle tour the world with his wife. Paul had an early role in Vancouver bicycle advocacy and at bringing cycle riding to a less elitist/athletic and more everyday commuter crowd through their shop.  They were among the early shops to embrace family friendly cargo bikes and  appreciated the role that electric would play in making cycling more broadly appealing.

Power assisted bicycles are classified in two categories in Saskatchewan. An electric assist bicycle is a 2 or 3-wheeled bicycle that uses pedals and a motor at the same time only. A power cycle uses either pedals and motor or motor only. Both must have engines with 500 watt power or less, and must not be able exceed 32 km/h (20 mph), i.e., electric motor cuts out at this speed or cycle is unable to go this fast on a level surface. The power cycle has to meet the Canadian Motor Vehicle Safety Standards (CMVSS) for a power-assisted bicycle. The power cycle requires at least a learner's driving licence (class 7), and all of the other classes 1–5 may operate these also. The electric assist bicycle does not require a licence. Helmets are required for each. Both are treated as bicycles regarding rules of the road. Gas powered or assisted bicycles are classified as motorcycles regardless of engine size or if using pedals plus motor. Stickers identifying the bicycle's compliance with the Federal classification may be required for power cycles by some cities or municipalities.[31]

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]

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.