Narumi Bicycle Design can manufacture frames compatible with the gearbox of EFFIGEAR of France. https://www.effigear.com/
The gear box is a highly durable system that is less susceptible to external influences such as weather and falls than external transmissions. In particular, EFFIGEAR's gear box has a different structure from conventional products using planetary gears, and the life of the internal transmission gear is very long, enabling stable operation over a long period of time. There are many other benefits such as optimized weight distribution and the realization of offset-free wheels.
Why don't you make this dream-like gear box bicycle? Narumi Bicycle Design helps you realize your dreams.