ADO build folding and city electric bikes and sit a step above the budget end of the market. The Air20S listed here is a 20 inch folding e-bike with a belt drive rather than a chain, which is the detail worth paying attention to: a belt needs no oiling, will not mark your trousers and lasts considerably longer than a chain, at the cost of a single fixed gear ratio. It is tagged UK road legal under the EAPC rules, so no registration, tax or insurance is needed to ride it on public roads.