Kimmo 

What do you guys make of this?

https://cyclingtips.com/2018/07/cera...en-drivetrain/

Seems pretty clever... Shifting seems like quite the hurdle though.

Any thoughts?

DiabloScott

It didn't catch on 100 years ago the first time someone came up with this groundbreaking invention. I predict a repeat.

ksryder

Right? What's old is new. Are they going to try to sell us solid rubber inner tubes too?

A bike share in a nearby town uses shaft drive bikes. I can see how that might be preferable for a fleet of low-performance rental bikes, a shaft might require a bit less maintenance and be a little less susceptible to wear and tear in that environment than a chain -- but I can't imagine it being a viable option for any kind of performance.

Although, as I'm typing this I'm wondering if it could be a solution to the gravel bikes in the mud problem...

HillRider

As a single speed it might be viable but as a multi-speed, I think the mechanical complexity will be dreadful.

ksryder

In the article they said they couldn't get a multi speed to work and would likely need to partner with a third party for the expertise to make that work.

Otherwise you'd have to settle for a IGH... which has its own drawbacks for performance applications.

fietsbob

a proprietary consumable cassette, still subject to wear,
as it is still exposed to environmental grit ..


Bevel gears on both ends can be kept in an oil bath..

such as BMW motorcycles have done for decades..

Riveting

If they could couple that shaft drive with a CVT style gearing mechanism instead, I think they could offer more than just eliminating drivetrain friction, which no one really gives a hoot about anyway.

DiabloScott

I saw this bike at the Marin Museum of Bicycling Joe Breeze told me that the company that made it used to pay Major Taylor and other racers to ride them in races for publicity... not so different from today's pro's and sponsorship deals I guess.

Kontact

90° bevel gear boxes are pretty inefficient. They are fine for motorcycles with power to spare, but for bikes it is like having your brakes lightly rubbing. Despite their claims of low friction, I think there is a power loss here from the way the parts interact that they aren't factoring. The roller is only momentarily in full gearing contact with the hub, so the output is not going to be continuous, for instance.

TGT1

Having those little bolts that hold the bearings on the ring in double shear like on their single speed isn't much different than the forces on the pins in a chain (double shear)
Cantilevered on the multiple speed? a whole different problem!

Those little bearings will need seals and shields to last for more than a few hundred miles and what happens when you hammer it and snap off one of those tiny bolts?

Kontact

The forces are different because the leverage of a roller at the 90° position is different than it is at 80° and 100°, just like a crank arm has different leverage depending on where it is. When the shaft is in a position right between two rollers, the leverage on the hub is higher than it will be a few degrees later when it is centered on one roller.

termv

As someone who worked professionally on BMW Motor Bikes, my opinion is that the shaft drive hasn't seen yet its full exposure.

BTW, in WWII the US Army insisted that the Harley's have a shaft drive.

Shimagnolo

I was not aware of that, so I went googling and...hell! HD copied the whole engine layout!

79pmooney

A couple of thoughts of the "what if" variety: I wonder if a cassette could be made with radial tracks the teeth for the rollers slide in, making for infinitely variable gearing. Obviously the current setup with rollers or teeth wouldn't work as the tooth spacing would change as the gear ratio was changed, For cleanliness, covers for both the cassette and bearings and the crankset and bearing could be made easily and could be quite aerodynamic. In fact, with well done covers, I could see the shaft drive being light, efficient and very long lasting (and clean!)

A shaft drive bike of 100+ years ago was shown on an earlier post and mention made of Major Taylor riding one of the bikes. He set at least one record using shaft drives. It's biggest drawback wasn't the additional friction, it was the difficulty in changing gear ratios.

Ben

termv

True, as well as the fact that motocross is the king discipline for any shaft drive.

On a side note, the BMW our relatives encountered in WWII wasn't even a BMW(really), it was based on a Zündapp KS 750.

Darwin would have had a good laugh.

Kimmo 

It looks like 70% of the respondents didn't RTFA.

The whole point here is to eliminate sliding friction and be more efficient - I would've thought Ceramicspeed's name would alert folks to that...

I like the idea of continuous ridges on the 'cassette' - hard to imagine exactly how that would look though... Obviously there would need to be discrete locations for the driver where new ridges appear and they're evenly spaced, and with some of the ridges being continuous, power could be maintained during a shift - but the shifting would need to be electronic, very rapid, and controlled extremely precisely...

Perhaps some sort of constant-engagement system like a car's gearbox? But then there's a weight and efficiency cost...

Shimagnolo

I did read it.
I like the out-of-the-box thinking.
A big plus here is that adding more speeds does not make the "cassette"-like piece wider.
i.e. you could add all the speeds you want w/o the DS spoke angle getting worse.

Now if they can figure out how to shift across the concentric rows of teeth while they are turning, it will be very interesting.

Kontact

I read the article. Please review my comments in that light.

JohnDThompson 

No neutral support wheel replacements for you!

HillRider

For motorcycles, shaft drive's main advantage is low maintenance requirements. Otherwise, compared to chain and sprockets, it is heavy, expensive, has lower efficiency and is nearly impossible to change overall gearing. It's use is limited to expensive touring bikes where the cost, weight and efficiency considerations aren't as important.

Marcus_Ti

Catch being...they still are using standard highly-dished wheels. Since the "cassette" (if you will) is only a fraction the stack-width of a regular cassette....there's no need for a dished wheel, certainly not a dished 11s standard wheel. Makes me wonder why if it was out of convenience or laziness or what that they did it they way they did.

ksryder

From the article I got the impression this was more a proof of concept than anything.

Ironfish653

Makes sense to try to fit it to a standard freehub, even if you don't need all the room. That way, the owner / builder can pick the wheels 'off-the-rack' for whatever kind of bike is being built, than being wedded to a proprietary hub, rim, and spoke count. (of course, proprietary frame for the shaft drive, but we're not counting that)

Incremental Gains is where it's at now, all those fractional percentage points can add up, if you take advantage of them. This is supposed to be something like 0.5% less friction than (optimal) Dura-Ace 11sp, which is like 99.0%

I saw it on GCN's Eurobike'18 video, and when he gave the crank a spin, it seemed like it went forever.

Dan Burkhart 

SquidPuppet

Manufacturing cost = $2,000,000.00
R&D cost = Guzillions$$
Honda's deep pockets = genius engineers

Chain driven