Ceramicspeed Driven - shifting teaser

Discuss light weight issues concerning road bikes & parts.
Conradsleight
Posts: 31
Joined: Tue Mar 10, 2015 5:27 am

by Conradsleight

Looks like they’ve got a working system now.

https://www.instagram.com/p/B133Iq0DqMu ... kgspxmq6ni

Of course I’m guessing this is a ways off from coming to market, but neat to see nonetheless.

by Weenie


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Alexbn921
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by Alexbn921

It will never work and it will never be as efficient as a chain.

Butcher
Shop Owner
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by Butcher

According to them, it is more effient than a chain drive. 49% less.
https://www.ceramicspeed.com/en/driven/

TobinHatesYou
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Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

The problem is you're changing the direction of force, not once, but twice with this system. The rear triangle can have basically ZERO lateral flex or the drivetrain will slip under load and send you into the ground.

mattr
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by mattr

Sounds like they've got the work experience/fresh grad to do the calculations......

Bit like those who think you can just use "science" to make gear boxes zero drag.

robeambro
Posts: 616
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

Talking about problems, this system requires a specifically-built bike, as the chainstays will need to be specifically made.
Lol.
I do not see how this could ever, ever, become a thing.

Nice engineering feat, that's all.

ghisallo2003
Posts: 655
Joined: Mon Jan 02, 2006 7:10 pm

by ghisallo2003

If it can be shown to work reliably, why not?

I can see it on a time trial or triathlon bike, with dramatically reduced rear wheel and bb spacing, like the early Walsers.

TobinHatesYou
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by TobinHatesYou

ghisallo2003 wrote:
Mon Sep 02, 2019 9:26 am
If it can be shown to work reliably, why not?

I can see it on a time trial or triathlon bike, with dramatically reduced rear wheel and bb spacing, like the early Walsers.

Again, they'll need to prove it won't slip or fail catastrophically under load.

alcatraz
Posts: 2254
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Only one roller touches a tooth at a given time? Can it really take sprinting torque without shattering into pieces? And wont such concentrated high pressure wear crazy fast?

TobinHatesYou
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by TobinHatesYou

And think about the lateral load being put on the wheel/hub during a sprint. That friction alone would nullify the theoretical efficiency gains.

aeroisnteverything
Posts: 201
Joined: Fri Aug 24, 2018 4:43 pm

by aeroisnteverything

For all the skepticism: this is obviously pretty similar to how a car's driveshaft works. Those things survive for 10s if not 100s of thousands of miles under MUCH higher torque/loads, and are pretty efficient. So IMO it's not a question of whether this can be made to work (it can), whether it can be made to work with low friction (it can), or whether it can made to be durable (it can). The question is whether all three of those are achievable while system weigh stays low enough for this particular application. Even in the current guise this looks heavy.

bm0p700f
in the industry
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by bm0p700f

Ceramic speeds entire product range is buy this it's really expensive and does not deliver. Kerching. So they sell a few drivers and kerching. It does not matter if it really does the business only that it can be shown to do the business in tests and people believe it does on the road.

People pay good money to have there head shut in the door. How many eggbeater pedals did I go through before switched to spds which I hate because they are heavy and because they work.

It's the exposed drive bearings that will be the problem. Given ceramic speed love of low friction these will be bearing will little sealing and water and grit will damage the races and the friction losses shoot up quickly. Those drive bearings are also small. Small bearings do wear quickly even in hubs where theres a shell to keep them in place. Exposed at the end of shaft they are going to be battered.

A car drivetrain has an enclosed gearbox bathed in oil and an enclosed final drive in a an oil bath. That's not the ceramic speed driven co dept at all.

Enclosed drive shaft bikes exist and coupled with a pi ion gearbox or roll off hub would be very reliable and heavy. Fine for e bikes though.

TobinHatesYou
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Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

A car's driveshaft also isn't directly involved in shifting...that's what the transmission is for. That's a lot more relative mass with actual toothed gears compared to one giant cheese grater and a some delicate roller bearings.

MichaelB
Posts: 636
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

aeroisnteverything wrote:
Mon Sep 02, 2019 10:36 am
For all the skepticism: this is obviously pretty similar to how a car's driveshaft works....
I think you need to look inside a car differential and see just how different that is to the CeramicSpeed marketing crap.

It’s a nice marketing tool, but anyone with even an inkling of engineering capability can tell you the many reasons why is it not practicable, workable, useable, manufacturable let alone desirable.

The fact that several websites have positively promoted numberless aero efficiency charts just shows how dumb this thing is

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Alexbn921
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by Alexbn921

aeroisnteverything wrote:
Mon Sep 02, 2019 10:36 am
For all the skepticism: this is obviously pretty similar to how a car's driveshaft works. Those things survive for 10s if not 100s of thousands of miles under MUCH higher torque/loads, and are pretty efficient. So IMO it's not a question of whether this can be made to work (it can), whether it can be made to work with low friction (it can), or whether it can made to be durable (it can). The question is whether all three of those are achievable while system weigh stays low enough for this particular application. Even in the current guise this looks heavy.
Cars driveshafts are not efficient. You are changing the direction of torque 2 time and each time introduces friction. This fact alone makes for a system that can never match a chain drive.
The whole center of the wheel would have to be an integrated hub support unit to resist sideloads and you would need much bigger stronger bearings. You would also need an extremely ridge overbuild frame as any flex would fubar the drivetrain. In addition the front ring would need to be 4x times or more, stiffer then current crankrings. Also the bearings and support from the frame would need to Maintain perfect alignment.

You are looking at several pound of reinforcement just to make it functional and then it won't have the longevity or efficiently of a normal drivetrain.

Spending any money on this is stupid and for marketing only. Now, gearboxes I am excited about, but again they will never be as efficient or as light. That efficiency can be offset with reliably and lack of maintance. Some bikes this will be worth it. Probably never see it on a race bike.

by Weenie


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