It has been almost a year since Shimano patented a thirteen-speed gearbox to be placed in the bike frame right next to the cranks. The cycling world, however, managed to discover this patent in November 2019 thanks to Jack Luke of BikeRadar. Perhaps it took so long because Shimano never used the English word “gearbox” in the patent, but talked about “a device for internally changing bicycle gears.” The Shimano gearbox is not based on the system of pinions, but rather on a system of two “cassettes” between which the power is transmitted by a chain, and there are actually three chains in the system. the third one goes out of the gearbox itself towards the rear wheel. The speed change is then ensured by an internal single derailleur or a movable guide which moves the chain between the wheels on both cassettes.
Because the patent describes seven speeds 19-to-41 cassettes, a thirteen-speed system with a 470% gear range is the result. Not much compared to 526% of Rohloff or a range of Pinion gearboxes which goes up to 636% for Pinion P1.18. Even today a conventional cassette of 10 to 50 teeth has a larger range. In general, it seems that the problem may also be the efficiency of the whole power transmission, which, according to some calculations, could be around 89%, which is again significantly worse than 95 to 96% of the classic shifting with derailleur, 94.5% for Rohloff or 90,5% for the Pinion. However, Shimano wants to solve this problem by an oil bath with a specially developed lubricant, which is given considerable attention in the patent. Also newly developed inner chain surface that should minimize friction.
So where is the potential advantage? For upright bicycles, the main advantage is in the weight being moved towards the center of the bike itself and also in having it on the suspended part of the bike as well as in the complete transmission housing, which becomes almost maintenance-free. Shimano assumes only modern electronic shifting. However, the advantage for recumbent seems to be fairly low right now.
Overall, the enthusiasm of the professional public is considerable. Some even talk about a possible breakthrough in the future of bicycle shifting, because the issue of “gearboxes” is targeted by the biggest player in the world of bicycle components. Also, the level of detail of the whole patent suggests that Shimano is already deep in the whole development and that it is perhaps close to the launch of the system. But just as much, the Japanese giant can only bluff. Whether with the whole idea or with some of its parts. We probably won’t know more this year, but they can surprise us for sure!
Because the patent describes seven speeds 19-to-41 cassettes, a thirteen-speed system with a 470% gear range is the result. Not much compared to 526% of Rohloff or a range of Pinion gearboxes which goes up to 636% for Pinion P1.18. Even today a conventional cassette of 10 to 50 teeth has a larger range. In general, it seems that the problem may also be the efficiency of the whole power transmission, which, according to some calculations, could be around 89%, which is again significantly worse than 95 to 96% of the classic shifting with derailleur, 94.5% for Rohloff or 90,5% for the Pinion. However, Shimano wants to solve this problem by an oil bath with a specially developed lubricant, which is given considerable attention in the patent. Also newly developed inner chain surface that should minimize friction.
So where is the potential advantage? For upright bicycles, the main advantage is in the weight being moved towards the center of the bike itself and also in having it on the suspended part of the bike as well as in the complete transmission housing, which becomes almost maintenance-free. Shimano assumes only modern electronic shifting. However, the advantage for recumbent seems to be fairly low right now.
Overall, the enthusiasm of the professional public is considerable. Some even talk about a possible breakthrough in the future of bicycle shifting, because the issue of “gearboxes” is targeted by the biggest player in the world of bicycle components. Also, the level of detail of the whole patent suggests that Shimano is already deep in the whole development and that it is perhaps close to the launch of the system. But just as much, the Japanese giant can only bluff. Whether with the whole idea or with some of its parts. We probably won’t know more this year, but they can surprise us for sure!
One of the sketches showing the look of a bike with the new gearbox 
Another view of the newly patented Shimano gearbox 
Shimano patented internal gearbox in early 2019. Here is the picture describing how it works.
