Jacque Lucque

• 🔥Exclusive🔥 I think Shimano is finally developing a bicycle gearbox! 💥😱🕺

Hello all, I haven't been on here in years. I used to be a regular poster but now I am the Assistant Editor at BikeRadar.com and have to look after those forums!

I've been doing some digging and have found a patent that strongly suggests Shimano is pretty far down the line developing a gearbox for bicycles.

This is, obviously, fairly huge news, and thought it may be of interest to you all.

Let me know what you think!

jgwilliams

Surely that's just an electric drive such as is fitted to many e-bikes. Electric motors would need to be geared down to drive cranks.

subgrade

No, it's not. It's basically an encased compact derailleur system with cassetes on both ends, at least one of them sliding in order to maintain a straight chainline.

Ferrouscious 

I'm not buying into the hype.

ThermionicScott 

I love how patent application diagrams still have to have that old-timey look.

mstateglfr 

Cool?

So would this be good for commuting since it would be enclosed? And for MTB or would it not shift fast enough and be a tank in weight?
So far I havent been riding and come upon a situation where I wished I had all the gears located in the bottom of the main triangle, so I havent explored this tech at all.

Gconan

Could you do away with the outer casing to save weight?

Kedosto

Meh. What's the date on that? The patent world is full of designs which never see the light of day. This could be something from long ago with no real intention to develop. Not that I wouldn't be interested in a Shimano gear box system, but I can't get too enthused about vapor (hard)ware.


-Kedosto

Berg417448

It says it was filed in 2017


https://patentimages.storage.googlea...90011037A1.pdf

wphamilton

One thing about the cassettes is puzzling. The two end combinations (19-41 and 41-19) wrap a total of 60 combined teeth. All of the others wrap 58 teeth. It seems goofy to add that extra bit at the ends when leaving it at 39 would keep the same chain length for all combinations, reducing or eliminating a DR-like tensioner. I'm sure the motivation is to get the same range as a standard DR system but it seems like a lot to give up, extreme even. Do you think that there's some other reason for it?

tyrion

I'm guessing a specific set of ratios is higher priority than avoiding a chain tensioner.

Jacque Lucque

I'd normally be with you on this but, given how advanced/detailed this patent is, I am led to believe Shimano may seriously be considering developing this one. I look at a lot (a lot!) of patents for work and this is different from most.

I am awaiting comment from the big S and will update the article as and when I hear back.

wphamilton

My first thought also, and the chart listing ratios seems to imply that, but the ratio with the logical 39 tooth is 2.05 compared to 2.15 with the 41. It seems like a lot to give up for a small improvement in range.

The tensioner drawbacks would be: increase in drag from the drive, an extra moving part to wear out or malfunction, an extra complication in the engineering and design, extra weight, and I could see it possibly reducing the persistence of chain lube. Intuition tells me that Shimano has an additional reason for that design. I suspect marketing (eg, has the *same range*)

Maybe they couldn't make the shifting work without the tensioner?

tyrion

It looks like one of the cassettes can move laterally by one cog-width, so a tensioner is required anyway.

wphamilton

Good point - I just saw the black line for some reason. So the advantage is 13 gearing steps instead of 7.

Still it's double the amount to take up with just the extra 2 teeth at the extremes which still bugs me.

tyrion

I'm not an engineer, but it looks to me like this thing could have less friction than a standard derailleur drivetrain - straight chainline, no sharp turns around jockey wheels, no tiny 11 tooth cogs...

CliffordK

I doubt this will be going anywhere. It will be locked up in patent for the next 20 years.

But, I just don't see any significant advantage of doing a chain sprocket shifting system over say planetary gear system.

I have thought about a triple gearing system on a Velomobile. But, that has quite different needs as a whole.

HTupolev

Perhaps, although it's not entirely obvious that the advantage persists once you consider the extra power transfer stages required to go from the cranks to the gearing system to the chainring to the rear wheel.

This thing isn't just a seven-speed sliding cassette paired with a seven-by crankset.

CliffordK

The problem is that one still has the double internal sprocket system, plus the chain (or belt) back to the rear of the bike. And, with suspension, also the need for a chain tensioner.

So one ends up with more moving parts.

By going with 19/41 X 41/19, I think it does give a pretty good gearing range, but initially only 7 speed with the equivalent of about 8 teeth between gears. That will be HUGE.

Of course the benefits of internal gearing may outweigh the costs for some applications.

tyrion

One of the cassettes moves laterally, giving it 13 gears.

79pmooney

Interesting. Basically an enclosed and perfect chainline 1X13, ie say, 52 x 11,12,14,16,18,21,24,27,32,36,42,47,52

Maybe a little heavier, maybe a little more friction than the conventional 1X when the 1X is squeaky clean and in a good chainline, but better on friction all the rest of the time. No chainring to smash MTB'ing. No rear derailleur to trash. Belt is far off the trail and should never contact anything. Nothing but a simple belt to keep clean. Drive trains that last many times longer. Yes, a tensioner would be needed for (most) suspension bikes but it can be really simple since the belt chainline never changes.

I like that the key 12,13,15,18,20 ratios are all there but I would never have to ride on those tiny cogs. The small 19 is so much better than a 11! As pointed out by the OP, big cogs and perfect chainlines are the way to go if you aren't wedded to derailleurs. I ride both derailleur bikes and fix gears. Yes, I can feel the difference easily.

Ben

Gresp15C

I'm not a patent lawyer, but part of my job is reading and understanding patents. The first thing to read in a patent is the Claims. This application has basically one primary claim, related to a sliding component. That begs the question of why it contains so much verbiage about gear ratios and such. One possibility is that the original application started out with a much broader set of claims, and these were whittled down during prosecution due to the discovery of prior art. On the other hand, it's possible to add more claims to an existing patent at a later date if they are "taught" in the body of the text, so the text could become the basis for additional patent claims in the future.

You can get more detailed info about a patent, such as the so called "prosecution history" by paying for a service that a patent law firm might have at their disposal, which can sometimes shed light on the "why" of patents that are hard to understand on their own. And of course it goes without saying that this is a patent application, not a patent.

In terms of a drive system with gear ratios that allow for perfect chainline, this is used for belt driven power tools such as drill presses, to give them multiple speeds with a single length of belt.

AndreyT

It is still a chain. In order to be shiftable, a chain always requires extra slack and a tensioner. "Keeping it the same length in all gears" would not in any way eliminate the need for that.

A belt can take this kind of advantage of "constant length" gearing. A chain cannot.

GamblerGORD53

Move over Kindernay. We now have a NEW contender for the STUPIDEST bicycle idea of ALL time.
CONGRATULATIONS. LOL hahahahahahahahahahaha

wphamilton

As tyrion pointed out, it has slack because there is a shift in between the same-length shifts. Otherwise I suspect that it could shift to a smaller gear without extra slack, and then have enough slack to shift up on the moving gear. Or vice versa for shifts in the other direction.