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Shimano's patent covers two opposing cassettes. The patent covers 7-speed cassettes with one of them offsetting, giving you 13 ratios in total. Even a pair of cassettes with 1 tooth changes in sprocket size (a constant change of 1 tooth, not a percentage change like we have now) gives you an almost constant change of 15 % between gears. I calculated this by using two 11-22 cassettes and got a parabola with 12,9 change between ratios in the middle of the two cassettes and 14,3 % at the ends. And I did this calculation less than a week this news article came out.
It came about after a (heated, of course) debate what kind of gear ratios current drivetrains had, where i plotted out all the gear steps for 9spd, 10spd Sram, 11spd Sram and 12spd Sram and Shimano (both XTR versions, 10-51 and 10-45). After that i was thinking about gearboxes and came to this opposing cassettes idea. Suffice to say, the Shimano patent takes it up a notch.
Anywho, Honda used a standard drivetrain in their gearbox, nothing fancy about that. Literally a custom derailleur, a (7spd i think) cassette and an input sprocket, that could slide left-right on the input axle to align the chain with the cassette. That means it was more or less what we still have in use now, but it was better protected. And with a shorter chain it was probably better protected from all the chain slap than the rest of the drivetrains in the day.
The beauty of the mythical Honda gearbox design (that wasn't raced) was that it was a CVT. The non-beauty of it was that rotating motion was transformed into reciprocating motion and back into rotation. I'm guessing here, but the fact it never made it tinto the bikes in the end means it didn't work that well (development would help, of course) and I'd also hazard a guess it wouldn't be all that efficient. Remember, the ordinary sprocket and chain combo is, clean, lubricated and straight, crazy efficient. Even with an offset-bent and dirty chain, it's still very much efficient. I think it'd be hard to see a gearbox on a race bike other than a DH bike with the weight and efficiency penalties.
I really liked the CVT concept that was leaked/guessed at by some magazine back then. Pure genius but perhaps not reliable.
Given what I've heard about sprag clutches on e-mtbs, the could also be part of the issue, getting the power to the output reliably.
It will be exciting to see if shimano takes their patent further. Really liking the idea of taking the weight off the rear wheel and putting it in the center
The non-CVT Honda, as written, uses a single cassette and a single input sprocket with a derailleur. While the Shimano patent does move the cassette side-to-side by one tooth (to gain extra ratios), the base shifting mechanism is switching the gear pair on which the chain runs. Of course you're going to have something derailleur-like to move the chain, but the point is, that when you shift the chain from one sprocket to the other on one cassette, you do it on the other cassette as well. Without the offset mechanism for one cassette, you would have 7 distinct gear pairs. This is completely unlike anything we have seen on bikes up to this point. 3x8 systems, while more similar, give you 24 more or less distinct gear combinations (with quite a lot of overlap when it comes to front sprockets). Shimano's patent gives you 14 in this case.
If they didn't have the cassette offsetting and kept the 7 gear pairs, this would be what car transmissions with constant mesh gear pairs do. But the gear selection here is done by moving the chain around. Or, if you will, a 'Honda like' version of the gearbox from the Shimano patent would use one cassette and 7 equally sized sprockets for the other shaft.
The kicker? You have a much more constant chain length if you have two opposing pyramids, so there's much less tensioning needed, unlike the systems we use now.
As for planetary gears and Pinion, you're wrong here again. Rohloff uses planetary gears and Nicolai's G-Boxx 1 used a Rohloff in a frame mounted box. G-Boxx 2 used a different system (something akin to pawl clutches if I'm not mistaken for gear selection and chains to connect the two shafts). Pinion uses standard involute gear pairs, just like a car, but uses in essence 2 serially mounted gearboxes, one 3 speed and the other 3, 4 or 6 speed, depending on the model (9, 12 or 18 speed model). The output of the second is concentric to the input of the first. But the pint here is they use constant mesh involute gear pairs, just like any manual car transmission. There are no planetaries involved here.
But yes, Shimano's patent should still be more efficient than a Pinion gearbox. There are less bearings, less meshed gears and the like in contact. There will be a drag to the meshed gears even if they are not powered.
https://youtu.be/niwYl4R7gA4
Interesting concept, YouTube video is a bit odd!
https://www.youtube.com/watch?v=DRt-CP2l474
ochain is super interesting. good find! straight to the tech page
https://www.ochain.bike/technical-support-page
And good job on the stock translator tone find.
I haven't experimented with chain-less descents but it would be easy to do. Just bring some pliers and a ziplock bag to pack the chain for each descent.