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…


  1. I wish them all the best in their work but have some doubt about intellectual property rights. I’m afraid some of solutions used here might already be protected with patents which would make it much more difficult to commercialize this product. I still wish Efneo all the very best though 🙂

  2. What I would rather have if somebody makes 12mm (either 135 or 142mm) rear hub, internally geared for 50%, 100% direct, and 150% OD. So I can have 1:1, 2:1 direct, and 3:1 overdrive.

    That would cover a whole lot of trail riding – going SS all the time is not to friendly to my knees.

  3. Love the idea and seems to be simple execution. I wish them the best. I know I’d use one if it didn’t feel like the current crank based systems.

    Walte – I think it will be awhile before they have efficiency numbers judging by their prototyping 😉

    I also agree with WG that IP rights will be difficult. There are a ton of designs and patents for this type of thing. Very few make it to market.

  4. Since no one here has seen how it works how can you assume this will violate any existing patents?

    You can’t patent “internal bottom bracket transmissions” or “3 speed bottom brackets”. If the design isn’t a direct copy of an already patented one, they won’t be successfully sued for patent infringement.

  5. The guy keeps saying “this is how it works” but all he is showing is how it operates – video and website are strangely lacking in any notion of how it ‘works’, also notice the jumps in the video – did they get the spanners out to change gear?

  6. Patents don’t protect inventions forever. Current patent law allows for an invention to be protected for 20 years from filing date or 17 years from the issue date meaning any patent issued prior to 1995 is allowed to be used by anyone. Otherwise, Suntour would be the top drivetrain manufacturer with their rear derailleur patent.

What do you think?