When dockless bike-sharing service Ofo first appeared in London last year, many people were bemused and irritated by its bright yellow bicycles parked or piled up outside tube stations and on street corners.

The number of Ofo bicycles in the capital quickly rose to almost 3,000 and spread to several cities around the UK. But just as quickly, the bicycles began to disappear after the company cut back its operations in the face of mounting losses.