Ceramicspeed Driven - shifting teaser

Discuss light weight issues concerning road bikes & parts.
Karvalo
Posts: 737
Joined: Fri Aug 10, 2018 6:40 pm

by Karvalo

MichaelB wrote:
Mon Sep 02, 2019 11:40 am
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.
No kidding. Bikes don't need a differential :noidea:

gurk700
Posts: 314
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

all that shit to save what? 3-5 watts? lol

by Weenie


User avatar
themidge
Posts: 1180
Joined: Fri Jan 13, 2017 4:19 pm
Location: underneath sweet Scottish rain

by themidge

^ +1! When they say their drivetrain is 49% faster than a normal one or whatever, the first thing we should all be asking is how much drag does a normal drivetrain create in the first place?
What's that? Hardly any you say? Well then, I won't bother.

TobinHatesYou
Posts: 4196
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

themidge wrote:
Mon Sep 02, 2019 8:27 pm
^ +1! When they say their drivetrain is 49% faster than a normal one or whatever, the first thing we should all be asking is how much drag does a normal drivetrain create in the first place?
What's that? Hardly any you say? Well then, I won't bother.

It's 98% to 99%. So for a pro in a 1400W sprint that would be...14W. And that's assuming those crazy perpendicular loads I mentioned don't create a whole lot of friction...and that the rear triangle is rigid enough to handle that kind of force.

And then we need to consider the comfort penalty with such a rigid rear triangle contributing too...
Last edited by TobinHatesYou on Tue Sep 03, 2019 3:52 am, edited 1 time in total.

MichaelB
Posts: 622
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

Karvalo wrote:
Mon Sep 02, 2019 6:20 pm
MichaelB wrote:
Mon Sep 02, 2019 11:40 am
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.
No kidding. Bikes don't need a differential :noidea:
Really ? :roll:

What I assumed aeroisnteverthing was referring to, and expected others to do the same, was the change in drive direction, not whether a bike needs a differentional. :noidea: to you too.

User avatar
themidge
Posts: 1180
Joined: Fri Jan 13, 2017 4:19 pm
Location: underneath sweet Scottish rain

by themidge

TobinHatesYou wrote:
Tue Sep 03, 2019 2:26 am
...crazy perpendicular loads...
I think you've hit on the biggest flaw with this system with that idea. It makes the most sense to me anyway.

I wonder whether this 'groupset' will only be used* in triathlon/ironman events (for marketing purposes probably) where riders won't be getting out of the saddle much.

*if it is ever used

User avatar
Alexbn921
Posts: 235
Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

themidge wrote:
Tue Sep 03, 2019 12:10 pm
TobinHatesYou wrote:
Tue Sep 03, 2019 2:26 am
...crazy perpendicular loads...
I think you've hit on the biggest flaw with this system with that idea. It makes the most sense to me anyway.

I wonder whether this 'groupset' will only be used* in triathlon/ironman events (for marketing purposes probably) where riders won't be getting out of the saddle much.

*if it is ever used
It will never be used as it is physically impossible for it to have a high efficiency then a chain. Not only that, but it will never be anywhere close to even double the weight of a conventional drivetrain.

Let’s take for example that you need at least 4 bearings on the driveshaft. Once loaded they will each take about 1-3 watts. That’s 4-12 watts of bearing drag in just the shaft. Add in the contact bearings and you have another 1-2 watts times 2. We are already at 6-16 watts.

Now you also have to factor in the huge increase in side loads experienced by the hub and crank bearings. You will have to use angular contact or needle bearings adding another 4-10+ watts.

Grand total of a perfect system will be at least 10 watts and more likely 20+ watts. At a 300 watt FTP with 20 watts of drag you have 93% efficiency.

Also add in at least 1kg for reinforcement to the frame and drivetrain.

https://www.neugart.com/en-us/planetary ... e-gearbox/

User avatar
wheelsONfire
Posts: 2963
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I would buy in to it, if it's extremely expensive and really bling!
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

spdntrxi
Posts: 3141
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

wheelsONfire wrote:
Tue Sep 03, 2019 8:27 pm
I would buy in to it, if it's extremely expensive and really bling!
it's ceramicspeed.. you can count on that.

User avatar
wheelsONfire
Posts: 2963
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

spdntrxi wrote:
Tue Sep 03, 2019 8:45 pm
wheelsONfire wrote:
Tue Sep 03, 2019 8:27 pm
I would buy in to it, if it's extremely expensive and really bling!
it's ceramicspeed.. you can count on that.
Puh, then i feel ok to take another loan. The more the better.
Anxiety over debts are well worth it if i am unique :D

To be fair, it would be extremely interesting to have the bike for a few days and ride solo.
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

TobinHatesYou
Posts: 4196
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Also what about high-G impacts like potholes, bunny hops. Chains just flap around.

What about wear and tolerances? Derailleurs deal with any slack in a chain and can be indexed. How can this system possibly adjust its equivalent of a b-gap without severely compromising its strength?

ichobi
Posts: 955
Joined: Thu Jan 19, 2012 11:30 pm

by ichobi

There's a feature article on cyclingtips for a close look.

Sent from my Pixel 2 XL using Tapatalk


IvanZg
Posts: 61
Joined: Thu Jan 10, 2019 3:10 pm

by IvanZg

From cyclingtip's article:
"Currently, CeramicSpeed’s newly rideable prototype is only meant to withstand about 200W."

gurk700
Posts: 314
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

IvanZg wrote:
Wed Sep 04, 2019 11:18 am
From cyclingtip's article:
"Currently, CeramicSpeed’s newly rideable prototype is only meant to withstand about 200W."
:lol: that sure saves watts!

by Weenie


ichobi
Posts: 955
Joined: Thu Jan 19, 2012 11:30 pm

by ichobi

Unless they use vibranium I can't see how they can make it light and strong, and viable.

If anything this could just be a marketing show, just like most of the thing CeramicSpeed does.

Sent from my Pixel 2 XL using Tapatalk


Post Reply
  • Similar Topics
    Replies
    Views
    Last post