# Multispeed shaft drive. The past revisited.



## Velobike (Jun 23, 2007)

Been done before, but it does look interesting.https://cyclingtips.com/2018/07/ceramicspeed-driven-drivetrain/


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## Mr Pig (Jun 25, 2008)

Not going to work, is it?


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## alexdi (Jun 25, 2016)

Armchair engineering: 

I think the idea has potential, but not as shown. Significant torque on the larger sprockets would just flex the "cassette" inward. This could be addressed by a stronger (heavier) cassette, or by backstopping it with an opposing bearing or the wheel itself. 

That's just the first problem. I've no idea how it's supposed to shift with cylindrical bearings. Ignoring the challenges of the actuation method (CS proposes various computerized solutions to move the shaft bearing element), they'd bind laterally on each sprocket. And, returning to torque, what's the expected lifespan of these parts when the effective engagement is only two or three teeth?


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## Mr Pig (Jun 25, 2008)

alexdi said:


> I think the idea has potential...


I don't.


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## alexdi (Jun 25, 2016)

Mr Pig said:


> I don't.


Well, you're a pig.


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## Mr Pig (Jun 25, 2008)

alexdi said:


> Well, you're a pig.


It's one of these idiotic ideas that anyone with an ounce of common sense knows should begin and end as a discussion over a beer one night. It's so blindingly obvious that to built it strong enough to function it would have to be heavier and less efficient than a chain while almost certainly less reliable.


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## Velobike (Jun 23, 2007)

alexdi said:


> ...I've no idea how it's supposed to shift with cylindrical bearings. Ignoring the challenges of the actuation method (CS proposes various computerized solutions to move the shaft bearing element), they'd bind laterally on each sprocket. And, returning to torque, what's the expected lifespan of these parts when the effective engagement is only two or three teeth?


I've thought of a way to do that. It's actually relatively simple.

My biggest misgiving is that it is not enclosed. I can't see it lasting long exposed.


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## Mr Pig (Jun 25, 2008)

Velobike said:


> My biggest misgiving is that it is not enclosed. I can't see it lasting long exposed.


A chain drive is not enclosed either.


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## chazpat (Sep 23, 2006)

From the article:

DrivEn is currently still only a single-speed prototype; a multi-speed system with nearly 500% of total range (more than what you get on a conventional compact double drivetrain) was envisioned and physically conceptualized for promotional photos, but it doesn’t actually work.


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## Mr Pig (Jun 25, 2008)

I would be very surprised if the single-speed prototype they show works under full load. The muti-speed design, not a chance.


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## alexdi (Jun 25, 2016)

To me, what's interesting is the idea of moving a pinion fore and aft to change gears. Other shaft-driven designs fix the pinions on both ends in place. This particular implementation may be nonstarter, but it's premature to suggest the entire concept is foolish.


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## J.B. Weld (Aug 13, 2012)

Interesting, but my Spidey senses tell me there has to be more friction involved with that design. Probably I'm totally wrong though.


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## Mr Pig (Jun 25, 2008)

alexdi said:


> It's premature to suggest the entire concept is foolish.


No it isn't. Bet you a Ferrari we never see this on a production bike. A proper production bike I mean, not some day-dream kick-starter wet fart.


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## wschruba (Apr 13, 2012)

Their friction chart cracks me up. They measured the friction of two other cross-chained systems with their own (presumably single-speed prototype) that is only designed to run in one gear. Rubbish.

An aligned chain-driven system under no tension has survived as long as it has simply because it IS the best at what it does. Even block chain (the worst case for 'sliding friction') work far better than that company would have you believe.

But hey, don't let that stop them. Maybe Specialized will finally be able to finish their tandem :lol:


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## J.B. Weld (Aug 13, 2012)

wschruba said:


> Their friction chart cracks me up. They measured the friction of two other cross-chained systems with their own (presumably single-speed prototype) that is only designed to run in one gear. Rubbish.


They measured the average friction across all the gears on the conventional system. The driveshaft prototype is only one gear but in theory every gear should have equal friction if it were multi-speed.

I only skimmed at first and chimed in with my gut feeling but had I noticed that Ceramic Speed was behind it I probably would have paused because those guys are serious about reducing friction. It seems doubtful that there will ever be a widely available multi-speed version but maybe on the track?


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## 127.0.0.1 (Nov 19, 2013)

garbage !


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## alexbn921 (Mar 31, 2009)

127.0.0.1 said:


> very very expensive garbage !


ftfy


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## J.B. Weld (Aug 13, 2012)

Velobike said:


> Been done before, but it does look interesting.


Like this? I've seen bikes with driveshafts and bevel gears.


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## Drew Diller (Jan 4, 2010)

What upset me about this tech experiment is that they marketed it as something it was not. It was too far down the range of dishonesty.

The headlines read "look at the future of bike gearing" and _if_ you made it to the fine details, "it doesn't shift, though it might in the future".

Please more honesty in marketing in the future. I can hear a room full of marketers laughing at this.

Irritating because perhaps a stripped down honest single speed version could have real applications, if you (somehow) made the rear wheel install/removal very easy to do.


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## life behind bars (May 24, 2014)

In a basement somewhere in the cycling world, someone is looking at this and turning it over and over in his/her mind........


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