Inspired by internally geared rear hubs, the founders of Efneo have spent three years prototyping and testing a front chainring gearbox capable of putting a useable series of gears into a package that’ll fit on any standard bicycle frame.
The result of their work is a three-speed, internally geared chainring that offers the equivalent of a 24/33/45 triple chainring crankset. In the first gear, the chainring speed is the same as the crankset and offers neutral gearing. The second gear is 36% faster than the first, and the third gear is 38% faster than second (88% faster than first gear).
Efneo is a family company out of Poland -the father is joined by his sister and two sons. When finalized, the design should weigh in well under 1,000g and only be about 20mm wide. That’s not any wider than a standard triple, actually pretty close to a double crankset. Pair it with a rear internally geared hub and you could have a very clean looking, virtually maintenance free city bike with a 600% gear range. Add in a belt drive and ooooohhh baby, now you’re talking!
Interesting video about the development process and some prototypes after the break…