The first AutoBike automatic transmission works like this:

• The rear wheel had three weights mounted on it, which, as the bike accelerates, would move out radially against springs
• By a system of cables, these weights moved a disc near the centre of the wheel outwards
• This disc engaged with the small roller mounted on this Autobike derailleur, moving outwards, in turn
• The derailleur, in its turn, moves the chain across the freewheel sprockets.

It's crude, it's nasty, it used a lot of fragile plastic parts - and it was soon renamed 'Classic' and effectively replaced by a more integrated design. Just to reinforce my point, this particular example has a broken roller.

But none of this addresses two fundamental problems:

• Firstly, the gear a rider requires does not correlate that well with rear wheel speed
• Secondly the sytem was not indexed - so it was more than possible for the speed of the bike to determine that your ideal chain position was exaclty in-between two sprockets.

Intriguingly crazy.

• Derailleur brands: AutoBike, manufactured by Falcon
• Country: USA, manufactured in Taiwan
• Date of introduction: 1995?
• Date of this example: unknown
• Model no.: unknown
• Weight: 293g including hanger plate, but with a broken roller and none of the terrifying mechanism that attached to the rear wheel.
• Maximum cog: 28 teeth?
• Total capacity: 28 teeth?
• Pulley centre to centre: 56mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: low normal
• B pivot: sprung
• P pivot: sprung
• Materials: steel