Is Shimano about to revolutionise the drivetrain (again)?
 

First they busted out Hyperglide, and made indexing work. Then they put the shifters where they belong. Then they came up with Di2, and transformed electronic shifting from an expensive curiosity into the state of the art.

Now, it's a fully enclosed gearbox. Before you roll your eyes, there's a twist or two: it uses a derailing chain, and one set of cogs moves laterally to maintain a perfect chainline. So it's lighter and more efficient than spur gears, and very likely to be more efficient than a pristine derailer drivetrain, and certainly more efficient than an even slightly dirty one. Not to mention more aero and far more robust...

Granted, it'll be heavier than a derailer drivetrain, but perhaps not by a huge amount, and it's a good place to concentrate the weight. It should certainly be possible to build a road bike using one of these that weighs less than 6.7kg...

https://www.bikeradar.com/news/shimano-gearbox


Oh yeah, thirteen speeds with a range of 470%.

Here's more https://www.bikeforums.net/general-c...e-gearbox.html

Seems awfully heavy to me.

Meh.

I'm not impressed, either, but ... their first indexing solution (positron) was awful. Their first SIS was nothing to write home about. Now, however, if I ever have to give up my 1973 MKM, I expect I'll have a ride that makes it easier to go faster. So the first gearbox may suck, but who knows? They may end up making a great one. After all, internal gears may have some advantages, and someone may be able to make that work....

I'm tipping this will be pretty sweet out of the box, with say, a 0.5kg weight penalty.

Shimano puts a foot wrong sometimes, but they learn from their mistakes, and constantly lift their game. Doubtless it'll be possible for them to improve this thing in the future, but IMO they'll make sure it's going to deliver the goods first time around.

If you consider the point that a huge chunk of this patent is deep in the weeds about the lube they'll use, it appears they're very serious about it.

How do you figure? The drawings show two chains inside the gearbox (pedals -> first cassette, then first cassette-> second cassette) then you have the chain/belt to the rear wheel. So there are three separate chains and four axes spinning all under load. Plus some sort of derailleur/tensioner for the chain between the two cassettes. A derailleur drivetrain only has one chain and two loaded axes.

Your point about cleanliness is well taken, but that's more the purview of gravel and MTB riding. Road drivetrains remain quite clean for a long time.

I hope to see more of this gearbox, but let's be honest about the challenges it faces and efficiency is likely one of them when compared to a road bike that is given reasonable maintenance. Based on the form factor of this, it looks to me like part of the motivation is to commonize frames for bicycles and electric mopeds

I don’t see this coming to pass any time soon. Almost all large companies file huge numbers of patents that they have no intention of using.

What would not surprise me, is fully automatic shifting. With today's electric shifting and watt meters, it would take very little in the way of additional electronics to shift up or down depending on how much torque is being applied to the crank.

It would obviously need to be easily adjustable, due to differences in riders and the hour to hour stamina of the rider. A single lever on the handlebars would suffice.

There's your next gen tranny for Ebikes. The scooter/commuter market better watch out.

20 years ago, Shimano patented but never produced a special 14-speed cassette that would fit in the same space as a 10-speed one, requiring a special chain and derailleur pulleys. It would have been just the thing for 1x systems. ;)

Yeah, maybe that. For road bikes? nah.

I am sure there have always been a lot of people who said every new thing couldn't work.

Give Shimano a few years and some development. Probably we will see this new system become as common as derailleurs are now .... or, as one person noted, as common as IGHs because most serious daily cyclists (not recreational sport cyclists) ride upright IGH bikes with enclosed chains .... when this can shift automatically and comes with an "easy-normal-sport" lever .....

This thing would totally pwn IGHs. As for efficiency compared with a standard drivetrain, I'm pretty sure the oil bath, no chain deflection and probably the big deal lube would more than make up for the extra complication, since it's all just chains and BBs. The total chain wrap in terms of degrees is probably double or more, so that's a strike against it, but I don't think it'd count for much.

Check out Proshift. I don't know much about them, or even if they are still in business, but it looks like they brought something to market for automatic shifting.

That’s pretty much what I was imagining, plus a little more. I was thinking power and cadence, but I didn’t think of heart rate and GPS. I was surprised at the $700 price, but given the cost of bike accessories, I shouldn’t have been.

I think Shimano (or other OEM) could do it built in to the existing electronics with less weight. And maybe even for less money.

Agree this should beat IGH. It's a tiny derailleur drivetrain compared to spur gears and doesn't have the same space constraints.


An oil bath is a negative for peak efficiency though due to windage losses. An enclosed oil bath is great for long term durability and is better than a dirty chain, but it's still more drag than running a chain through air. I'd actually expect Shimano keeps the oil level in the box to a minimum so it's more of a drip than a bath. Don't forget this also adds two chains compared to a standard drivetrain and an additional four axle bearings. No matter what the lube, I doubt they will be able to drop the friction in these areas to half or a third of what current drivetrains run at these points. More likely Shimano's target for efficiency is to be close enough to a derailleur drivetrain that most riders won't really notice the additional drag. The selling points for this are all related to keeping things enclosed.

Given that a traditional derailleur/cassette/chain/chainring drivetrain is less than ideal for the ebike platform, I wonder if Shimano is working toward a drivetrain that would be more universal - fewer different parts from ebike to real bike?