Sinclair Research worried that Clive Sinclair himself was using his own personal wealth to fund his inventions. By 1990 the company's entire staff had been reduced to just Sinclair himself, a salesman/administrator, and an R&D employee. By 1997 only Sinclair himself was working at his company. In 1992, the "Zike" electric bicycle was released, Sinclair's second attempt at changing people's means of transport. It had a maximum speed of , and was only available by mail order. Much like the C5, the "Zike" was a commercial failure, and sold only 2,000 units. In 1999 Sinclair released the world's smallest radio, in the
Personal air vehicle breakthroughs. A ground transport alternative is enabled by unmanned aircraft technologies: Autonomous Systems and electric propulsion. Barriers include aviation safety, airworthiness, operating costs, usability, airspace integration, aircraft noise and emissions, tackled first by small UAS certification then experience. Other names discussed include PIVITOLs (Personal Vertical TakeOff vehicles), Air-cars, PACs (Personal AirCraft), AVs (Air Vehicles). The first technical paper to explain the difference in vehicle characteristics between PAVs and existing General Aviation single engine piston aircraft was "Personal Air Vehicles: A Rural/Regional and Intra-Urban On-Demand Transportation System" by Mark D. Moore (the NASA PAV Sector Manager) from NASA Langley Research Center.