Since cyclists' legs are most efficient over a narrow range of pedaling speeds, or cadence, a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. Some, mainly utility, bicycles use hub gears with between 3 and 14 ratios, but most use the generally more efficient dérailleur system, by which the chain is moved between different cogs called chainrings and sprockets in order to select a ratio. A dérailleur system normally has two dérailleurs, or mechs, one at the front to select the chainring and another at the back to select the sprocket. Most bikes have two or three chainrings, and from 5 to 11 sprockets on the back, with the number of theoretical gears calculated by multiplying front by back. In reality, many gears overlap or require the chain to run diagonally, so the number of usable gears is fewer.
The Netherlands has a fleet of 18 million bicycles. E-bikes have reached a market share of 10% by 2009, as e-bikes sales quadrupled from 40,000 units to 153,000 between 2006 and 2009, and the electric-powered models represented 25% of the total bicycle sales revenue in that year. By early 2010 one in every eight bicycles sold in the country is electric-powered despite the fact that on average an e-bike is three times more expensive than a regular bicycle.
Metro is a brand that has been around since 2010, and it is one of the top sellers. That is mostly because their products are solid, good value, with good power and good features. Metro Hybrid is a part of urban electric bikes family, and it is really well set up for the urban and light trail riding. Metro has a diamond frame and 700c (28-inch) wheels with sporty 38mm Schwalbe Marathon tires, so you get real quality tires. A big capacity battery of 624Wh will carry you 20–40 miles, with the top speed of 28 mph with assist, or 20mph using throttle only. The comfort is decent with adjustable handle bar, as well as suspension seat post and a suspension fork. Overall, this bike offers good value for the price, with outstanding range and power for its class.
Some e-bikes operate in pedal-assist only, others have a throttle, and some have both. Generally, pedal-assist only bikes will provide multiple power settings to choose from to help customize your ride, while bikes with both throttle and pedal-assist will have limited pedal-assist options. With these bikes, the throttle provides full control (when needed) while pedal assist is just a secondary option, great on straightaways or open road.
Simple, convenient, cheap, and economical—bicycles are one of the world's favorite forms of transportation. But they're not for everyone. They can be hard to pedal up and down hills or with heavy loads, and elderly or disabled people may find them impossible to manage. In the last few years, a new generation of electric bicycles has begun to revolutionize our idea of environmentally friendly transportation. These new cycles have all the convenience of cars with all the simple economy of ordinary cycles. Let's take a closer look at how they work.