CeramicSpeed tests radical drive shaft concept in Specialized wind tunnel leading to claims it’s more aero than a standard groupset

Nick T wrote:

Imagine how fast a Ceramic Speed unicycle would be

That would be nuts

ktache wrote:

Readybike, the bicycle hire scheme in Reading had drive shaft bicycles.  I doubt if they worried about efficiency much.  Driven a 3 speed internal hub.  One day they just all disapeared.

Mobike hire bikes in Manchester were the same, both in terms of shaft drive and sudden disappearance.

ktache wrote:

Readybike, the bicycle hire scheme in Reading had drive shaft bicycles.  I doubt if they worried about efficiency much.  Driven a 3 speed internal hub.  One day they just all disapeared.

I rode one once - truly a once in a lifetime experience. The teeth jumping on the shft drive was the least of it.

Bmblbzzz wrote:

I used to have a shaft-drive motorcyle: a CX500. It made removing and refitting the rear wheel much easier and cleaner (okay, less filthy) than with a chain. Can't comment on efficiency, don't recall torque steer being a problem, but the shafts do wear and unlike a chain you can't see it till it's too late (it didn't start slipping or skipping, it would work perfectly normally until one instant it suddenly lost all drive; I had this happen on two separate bikes, same model, and to friends with CXs). 

As for a peak of 1500W, I can only wish! 

I knew someone who had a CX500, and since it wa the only bike I'd ever seen with a driveshaft I thought it was pretty cool. I do see the advantages of shaft drive bikes, but I always felt the cost of replacement of the driveshaft outweighed the low maintenance aspect- parts were/are quite specific. 

The torque steer part is something you'd run into as an issue on a more modern high end bike- something like an R6 upward. The power to weight ratio is so high, and the engine generates so much torque, the chassis would have to be beefed up significantly to deal with it, especially around the rear subframe. This adds weight, and when added to the weight of the driveshaft it's quite significant. 

Nick T wrote:

Great to see a ball bearing seller do what all those motorcycle manufacturers and their billions invested in R&D couldn’t, and come up with a shaft that’s more efficient than a chain. Perhaps that last 1% of efficiency can be found by rotating the rider and cranks by 90 degrees so that the legs can drive the shaft directly?

Sorry, but you blatantly don't know what you're talking about trying to draw a comparison here. 

1) They're a long way from coming up with anything. They have a conceptual design, that's it. Hasn't been subject to any kind of real world testing- as far as I know they haven't even come up with a system that can change gears (yet). It remains to be seen whether this will progress to being a production bike or whether it will die at concept phase- it wouldn't be the first idea to be shown at Eurobike only to be never seen again. 

2) Shaft-driven motorbikes do exist- there a quite a number of large touring bikes that use shaft drives. Their disadvantages are generally considered to outweigh their advantages, which is why they're not more popular. It remains to be seen whether the Ceramic Speed design will be any different (assuming it makes it past concept).

3) The problems facing a shaft-driven motorbike aren't about some relatively pointless marginal gain in efficiency- if you want to make a motor driven drive train more efficient you'd start at the engine and gearbox. Gettin 1% more out of the power transfer system is neither here nor there.

4) While in theory bicycles and motorcycles have some similarities in the problems they face, in reality it's a completely different playing field. Torque steer isn't something a bicycle has to contend with- it's one thing designing a system that can withstand a peak of maybe 1500W, it's another to design a frame for nearly 100 times that. Drive chains on motorbikes also don't have to deal with changing chain lines, which is most of CeramicSpeed's raison d'etre.

It might sound like I'm massively down on the CeramicSpeed concept...I'm actually not, I like innovation, even just for innovation's sake. However, I do think this will remain an ultra-high end design, and we won't see it trickling down into the affordable range any time soon, if at all. 

Mathemagician wrote:

Nick T wrote:

Great to see a ball bearing seller do what all those motorcycle manufacturers and their billions invested in R&D couldn’t, and come up with a shaft that’s more efficient than a chain.

2) Shaft-driven motorbikes do exist

Shaft-driven motorbikes exist, it's a shaft-driven motorbike that's more efficient than a chain that doesn't. Shaft-driven pedal bikes have existed for years and years too.

https://en.wikipedia.org/wiki/Shaft-driven_bicycle#History

On the other hand, you're right that there's no good reason why a  motorcycle manufacturer should concentrate on trying to do that, and that this isn't yet close to a working system.

Mathemagician wrote:

Nick T wrote:

Great to see a ball bearing seller do what all those motorcycle manufacturers and their billions invested in R&D couldn’t, and come up with a shaft that’s more efficient than a chain. Perhaps that last 1% of efficiency can be found by rotating the rider and cranks by 90 degrees so that the legs can drive the shaft directly?

Sorry, but you blatantly don't know what you're talking about trying to draw a comparison here. 

1) They're a long way from coming up with anything. They have a conceptual design, that's it. Hasn't been subject to any kind of real world testing- as far as I know they haven't even come up with a system that can change gears (yet). It remains to be seen whether this will progress to being a production bike or whether it will die at concept phase- it wouldn't be the first idea to be shown at Eurobike only to be never seen again. 

2) Shaft-driven motorbikes do exist- there a quite a number of large touring bikes that use shaft drives. Their disadvantages are generally considered to outweigh their advantages, which is why they're not more popular. It remains to be seen whether the Ceramic Speed design will be any different (assuming it makes it past concept).

3) The problems facing a shaft-driven motorbike aren't about some relatively pointless marginal gain in efficiency- if you want to make a motor driven drive train more efficient you'd start at the engine and gearbox. Gettin 1% more out of the power transfer system is neither here nor there.

the claim in the article which you don’t appear to have read, is that a chain is between 90-98% efficient, and this shaft drive is 99% efficient, thtat what I am poking fun at. 

I am well aware of shaft driven motorbikes, I am a motorbike as well as a cyclist. The extremely popular BMW GS like what Ewan McGregor rode around the world on, is a shaft drive. Great for that sort of riding, low maintenance, less chance of snapping etc. Shafts have been around for a long time so it’s well established that on the flip side of reliability that they aren’t as efficient as a chain. 

Shaft drive bicycles have been around just as long, the chain was the improvement. Just like pneumatic tyres taking over from solid wheels, you’ll always see nonsense like this stunt trying to bring back some largely obsolete technology packaged as new and improved before it disappears for another few years 

Nick T wrote:

the claim in the article which you don’t appear to have read, is that a chain is between 90-98% efficient, and this shaft drive is 99% efficient, thtat what I am poking fun at. 

I am well aware of shaft driven motorbikes, I am a motorbike as well as a cyclist. The extremely popular BMW GS like what Ewan McGregor rode around the world on, is a shaft drive. Great for that sort of riding, low maintenance, less chance of snapping etc. Shafts have been around for a long time so it’s well established that on the flip side of reliability that they aren’t as efficient as a chain. 

Shaft drive bicycles have been around just as long, the chain was the improvement. Just like pneumatic tyres taking over from solid wheels, you’ll always see nonsense like this stunt trying to bring back some largely obsolete technology packaged as new and improved before it disappears for another few years 

So basically what you're saying is...I completely missed the sarcasm in your post?

Now I feel sheepish.

Nick T wrote:

Great to see a ball bearing seller do what all those motorcycle manufacturers and their billions invested in R&D couldn’t, and come up with a shaft that’s more efficient than a chain. Perhaps that last 1% of efficiency can be found by rotating the rider and cranks by 90 degrees so that the legs can drive the shaft directly?

Is a penny farthing bike 100% efficient?

Bungle_52 wrote:

Nick T wrote:

Great to see a ball bearing seller do what all those motorcycle manufacturers and their billions invested in R&D couldn’t, and come up with a shaft that’s more efficient than a chain. Perhaps that last 1% of efficiency can be found by rotating the rider and cranks by 90 degrees so that the legs can drive the shaft directly?

Is a penny farthing bike 100% efficient?

Yes.

Jamminatrix wrote:

This drivetrain again? Cool hype piece to make CeramicSpeed look more innovative than they really are, but never going to work... There's not enough inherent rigidity in the system to keep it from skipping gears. The only way to shift is free-spinning under no load. Cannot be used in dirt/muddy environments.

I would have thought it made more sense to have the shifting at the front where everything is more rigid, but then you wouldn't be able to see it...

Jamminatrix wrote:

This drivetrain again? Cool hype piece to make CeramicSpeed look more innovative than they really are, but never going to work... There's not enough inherent rigidity in the system to keep it from skipping gears. The only way to shift is free-spinning under no load. Cannot be used in dirt/muddy environments.

Sorry but unless you are involved with the design of this system or a similar one you can't make such sweeping statements about an in development product.

In terms of rigidity the shaft ends are seated pretty deep in the teeth so I don't see them slipping out easily. The distance between the axle and the contact point is also not particulary far.

In terms of working with muck, firstly as seen on the second prototype it can be enclosed more than a chain drive and secondly the gear teeth should shed dirt due to CF load, finally the roller bearings are not making snug contact in the teeth on the cogs they should just push dirt on to a non contacted surface.

I can also conceptually think of a number of ways to make this shift gears under load. 

One would be that as roller bearing element moves down the shaft it changes phase slightly (moving on a spline) deloading it as the move is triggered. The same trick is them pulled in the oposite direction to allow the roller bearing element to match the next cog.

Shifting will be electrically actuated with timings more in line with a variable valve timing system on an ICE than anything on a bike.

massive4x4 wrote:

I can also conceptually think of a number of ways to make this shift gears under load. 

So can I, but I can absolutely guarantee that it's getting a reliable and robust gear shift that's going to sink this concept: it's a much more complex engineering problem than anything demonstrated so far.

massive4x4 wrote:

Jamminatrix wrote:

This drivetrain again? Cool hype piece to make CeramicSpeed look more innovative than they really are, but never going to work... There's not enough inherent rigidity in the system to keep it from skipping gears. The only way to shift is free-spinning under no load. Cannot be used in dirt/muddy environments.

Sorry but unless you are involved with the design of this system or a similar one you can't make such sweeping statements about an in development product.

In terms of rigidity the shaft ends are seated pretty deep in the teeth so I don't see them slipping out easily. The distance between the axle and the contact point is also not particulary far.

In terms of working with muck, firstly as seen on the second prototype it can be enclosed more than a chain drive and secondly the gear teeth should shed dirt due to CF load, finally the roller bearings are not making snug contact in the teeth on the cogs they should just push dirt on to a non contacted surface.

I can also conceptually think of a number of ways to make this shift gears under load. 

One would be that as roller bearing element moves down the shaft it changes phase slightly (moving on a spline) deloading it as the move is triggered. The same trick is them pulled in the oposite direction to allow the roller bearing element to match the next cog.

Shifting will be electrically actuated with timings more in line with a variable valve timing system on an ICE than anything on a bike.

Agreed - amusing how negative some are towards this.

Htc wrote:

massive4x4 wrote:

Jamminatrix wrote:

This drivetrain again? Cool hype piece to make CeramicSpeed look more innovative than they really are, but never going to work... There's not enough inherent rigidity in the system to keep it from skipping gears. The only way to shift is free-spinning under no load. Cannot be used in dirt/muddy environments.

Sorry but unless you are involved with the design of this system or a similar one you can't make such sweeping statements about an in development product.

In terms of rigidity the shaft ends are seated pretty deep in the teeth so I don't see them slipping out easily. The distance between the axle and the contact point is also not particulary far.

In terms of working with muck, firstly as seen on the second prototype it can be enclosed more than a chain drive and secondly the gear teeth should shed dirt due to CF load, finally the roller bearings are not making snug contact in the teeth on the cogs they should just push dirt on to a non contacted surface.

I can also conceptually think of a number of ways to make this shift gears under load. 

One would be that as roller bearing element moves down the shaft it changes phase slightly (moving on a spline) deloading it as the move is triggered. The same trick is them pulled in the oposite direction to allow the roller bearing element to match the next cog.

Shifting will be electrically actuated with timings more in line with a variable valve timing system on an ICE than anything on a bike.

Agreed - amusing how negative some are towards this.

negative or realistic?