for cars and some SUVS. E-bikes developed in Switzerland in the late 1980s for the Tour de Sol solar vehicle race came with solar charging stations but these were later fixed on roofs and connected so as to feed into the electric mains. The bicycles were then charged from the mains, as is common today. While e-bike batteries were produced mainly by bigger companies in past, many small to medium companies have started using innovative new methods for creating more durable batteries. State of the art, custom built automated precision CNC spot welding machines created 18650 battery packs are commonly used among do-it-yourself e-bike makers. Design variations Not all e-bikes take the form of conventional push-bikes with an incorporated motor, such as the Cytronex bicycles which use a small battery disguised as a water bottle. Some are designed to take the appearance of low capacity motorcycles, but smaller in size and consisting of an electric motor rather than a petrol engine. For example, the Sakura e-bike incorporates a 200 W motor found on standard e-bikes, but also includes plastic cladding, front and rear lights, and a speedometer. It is styled as a modern moped, and is often mistaken for one. Converting a non-electric bicycle to its electric equivalent can be complicated but numerous 'replace a wheel' solutions are now available on the market. An Electric Pusher Trailer is an e-bike design which incorporates a motor and battery into a trailer that pushes any bicycle. One such trailer is the two-wheeled Ridekick. Other, rarer designs include that of a 'chopper' styled e-bike, which are designed as more of a 'fun' or 'novelty' e-bike than as a purposeful mobility aid or mode of transport. Electric cargo bikes allow the rider to carry large, heavy items which would be difficult to transport without electric power supplementing the human power input. There are many e-bikes design variations available, some with batteries attached to the frame, some housed within the tube. Some use fat tires for improved stability and off-road capability. Various designs (including those mentioned above) are designed to fit inside most area laws, and the ones that contain pedals can be used on roads in the United Kingdom, among other countries. Folding e-bikes are also available. Electric self-balancing unicycles do not conform to e-bike legislation in most countries and therefore cannot be used on the road, but may be legal to use on