What IS this?

RARE VINTAGE 80’s SUPER BIKE 16 SPEED ROAD BIKE,Campiogear Graphlite Group | eBay

I have no idea but it sure is weird.


The amazing lightness of plastic… combined with cottered steel cranks.

Am I crazy or is that a spirograph for a chainring?

Expanding chainring that changed size by rotating the toothed disc relative to the chainring segments, which traveled along the spiral tracks. Only the very cheapest and nastiest version made it to Oz; I vaguely remember seeing the bikes sold in Kmart back in the day. From memory, the lever moved the seat tube lever down till it engaged the toothed disc and you then pedalled forwards or backwards to adjust the chainring size, released the lever and you pedalled off in the new gear, if you hadn’t rolled to a stop while changing gear.

The Deal Drive was a nicer spring-loaded expanding chainring system that almost made it to market. It autochanged, depending on pedal pressure, so you were always pedalling forwards and applying drive. The spring tension was adjustable at the crank.