Shimano's patent for a new gearbox design.

Drago

Flouncing Nobber
It all comes down to price. It could be awesome, but if it's a bag of sand more expensive than an already excellent XT geartrain then few will buy it.

Watching with interest though.
 

ColinJ

Puzzle game developer
It looks interesting!

I like the idea of a weatherproof and therefore almost wearproof drivetrain, especially with lower drag than a perfectly set up new derailleur system.

If it weighed no more than a conventional setup, cost less than (say) £750, and came with a 10+ year warranty then I think they would have a world-beater.

If it weighed more, cost £2,000+, and had no more than (say) a 3 year warranty - no thanks!
 

Globalti

Legendary Member
The reason why nobody has ever built a successful alternative to the derailleur it its light weight, simplicity and ease of repair. I don't buy the story about increased drag on an imperfect chainline and I would even suggest that an enclosed gearbox with meshing gears and several additional sets of bearings would cause more drag then a simple derailleur system where the only bearings are on the BB and the rear hub.

On top of that you've got the extra weight, the cost of manufacture and the need for spares. With internal lubrication you'll need seals, meaning additional drag. The stresses inside the gearbox mean the casing will need to be strong and hence heavy compared to a simple derailleur system which is, in simple engineering terms, two constantly renewing levers of variable length connected by a chain.

So I'm out.

What does @Yellow Saddle think of it?

Edit: bloomin' boring video, by the way. Why use five words when fifty will do?
 

raleighnut

Legendary Member
Location
On 3 Wheels
The reason why nobody has ever built a successful alternative to the derailleur it its light weight, simplicity and ease of repair. I don't buy the story about increased drag on an imperfect chainline and I would even suggest that an enclosed gearbox with meshing gears and several additional sets of bearings would cause more drag then a simple derailleur system where the only bearings are on the BB and the rear hub.

On top of that you've got the extra weight, the cost of manufacture and the need for spares. With internal lubrication you'll need seals, meaning additional drag. The stresses inside the gearbox mean the casing will need to be strong and hence heavy compared to a simple derailleur system which is, in simple engineering terms, two constantly renewing levers of variable length connected by a chain.

So I'm out.

What does @Yellow Saddle think of it?

Edit: bloomin' boring video, by the way. Why use five words when fifty will do?
There's a couple of bearings/bushes in the jockey wheels too and judging by the fact that some people 'wear out' these there must be some drag on those.
 

Globalti

Legendary Member
Have you ever spun a jockey wheel with your fingers? There's almost no resistance. Try spinning a gear shaft that passes through an oil seal, by comparison.
 

Drago

Flouncing Nobber
The Sturmey Archer 3 and 5 speed was, for half a century or more, an excellent alternative to derailleur type systems. It's been done before, and that it hasn't been done since shows as much about pricing, marketing, and fickleness to fashion of cycling's big spenders, not any inherent disadvantage of self contained gearing systems.
 

Smokin Joe

Legendary Member
I

If it weighed more, cost £2,000+, and had no more than (say) a 3 year warranty - no thanks!
It will certainly cost more than most people are prepared to pay - initially. But that's true of all new technology, once R&D costs are recouped and production levels rise prices fall. Integrated shifters and carbon frames cost eye watering amounts when they were introduced yet now both are common currency. Shimano don't faff about when they develop new systems, it isn't guaranteed to succeed but it's certainly a case of "Watch this space".

It also makes belt drive a very doable proposition, something not possible with derellieur gears.
 

Ian H

I am an ancient randonneur, & I stop often for tea
Location
East Devon
The more you build into the frame, the less 'upgradeable' your bike becomes. With a hub gear you can replace it if something better comes along, or you just want to change it. This is a move further towards built-in obsolescence.
 

Ajax Bay

Veteran
Location
East Devon
Acknowledging the BikeRadar presenter's caveats, he seems to suggest that the potential 'perfect' chainline offered by such a gearbox is a key 'efficiency' factor. Not sure about that.
A paper reported in the reputable IHPVA Technical Journal specifically "On the efficiency of bicycle chain drives" by James B. Spicer et al (Johns Hopkins University, Baltimore) and Masahiko Fukuda and Masao Terada (Shimano Inc., Product Engineering Division) (2000) suggests that:
" chain-line offset and chain lubrication have a negligible effect on efficiency under laboratory conditions."
It's rather heavy (bit like this possible gearbox, I suspect) so here are is (my) edited DISCUSSION AND CONCLUSIONS extract:
> Primary factors affecting the efficiency include the sizes of the sprockets in the drive and the tension in the chain.
It was found that larger sprockets provide more efficient transfer of power while smaller sprockets proved
to be less efficient. . . . Typically, a 2–5% loss difference was measured between the 52–11 and the 52–21 sprocket combinations
> . . . the efficiency of the chain drive varied as a function of chain tension. It was found that the efficiency varied linearly
with the reciprocal of the average chain tension [highest efficiencies occurring at high chain tensions] . . . highest efficiency measured in the study [was] 98.6%, and the lowest, 80.9%, . . .
> It was found that chain-line offset and chain lubrication have a negligible effect on efficiency under laboratory conditions.
> No significant quantifiable effect of lubrication could be inferred from these tests.
[Summary] . . . the efficiency of the bicycle chain drive depends intimately on the chain operation as it engages and
departs from the sprockets on the high tension part of the drive."
 
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