Too bad they didn't also test the aero impact (if any) of the CeramicSpeed OSPW compared to a stock setup.

---

Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Sounds promising for a future drivetrain generation... BUT.. 1% for friction loss when there are 2 points of contact at 90 degree, it’s very hard to believe. Too good to be true kinda thing.
Ceramic speed has assessed the aero facts with the wind tunnel experts, now it would be great if they can take the prototype with the independent friction facts experts.

"To date, the Venge is Specialized’s most aerodynamic road bike, with every aspect of its design challenged and tested"
2016 Venge Vias rim brakes is Specialized’s most aerodynamic road bike, not 2019 venge.

I was thinking the same thing when I read that.. The rim brake Venge Vias tested a couple of watts quicker then the '19 disc Venge, so someone's talking out of their ass.

Yeah I've been extremely sceptical about the likely performance of this contraption. It seems like a study in bad engineering.

"Driven"
https://www.ceramicspeed.com/.../driven_brochure.pdf
is an absolute thrilling invention from an engineering point of view, but it still seems still to be a prototype?

They should first introduce it into the market and proof it works in "normal day cycling" before theorizing over aero advantages.

They already claim two tests of OSPW (by others) and given there is nothing for CS to gain in terms of performance (only reputational loss), they wouldn't either test it carefully, or publish the results, or indeed be trusted to do so.

I'm no mechanical engineer, but to my lay-person's view it would seem that two points contact could potentially be better than the 110-120 points of contact in a traditional chain, each with pins/bushings and plates all rubbing against each other? I think the benchmark claim for Ceramic Speed's waxed and coated race-spec chains is a <5W loss; I guess that would be for a realistic power output and cadence, but does that sound reasonable/beatable for a direct-drive mechanism like this?

When I first saw this a few years ago I thought it was the dumbest idea I'd ever seen, but I think I'm coming around to it now. It doesn't actually look too bad on a bike and it would certainly be a hell of a lot easier to keep that drivetrain clean! It's just a shame that it's Ceramic Speed pushing it, so it'd probably cost $10k+ for a groupset if it ever actually reaches the consumer...

There is so much wrong and bullshit in their marketing material, I can't even bring myself to comment on it.

Introduce it in "normal day cycling"? You mean like the shaft drive that was invented about 130 years ago? and now exists on the scrapheap of history?

Its an interesting one this, I often see pics/ videos of this system come up on FB, and normally its not longe before somone says its not new and was built 100 years ago, wel yeah there were shaft gear bikes with 3 speeds, but thats actually a different thing, Shaft gear, as a gear that slides against another gear... this does not have the sliding mesh of gears, the points of contact stay fixed together, and the movement is taken care of by a bearing, a very differint situation in terms of friction compared to meshing gears, or chains, essentially sliding vs rolling.

I do wonder about the longevity of those tiny balls under rome gorilla mashing the pedals though, and the side loadings on that "flat rear cassette thing" i can see it flexing and jumping under high loader or when worn.

Pray tell, what's happening where the outside shell of the bearing contacts the cheesegrater?
(hint: it's not rolling)

This x 10^6. I like how they're all free of seals, and ready to eat whatever debris and dust and mud and sticks come their way. You could put seals back on, but I guess there might be a bit more friction then...

Cheesegrater! i like that term :D

looking at it, I would say the bearing "rolls" agains the cheesegrater, or at least as soon as it makes contact, as theres nothing holding the bearing outer surface still, I would certanly disagree that it slides( to any meaning ful amount anyway).
Interestingly i was lust looking at some more pics and the front setup is actually textured where it contacts the chain ring i'd not noticed that before.

I was thinking the same about the bearing seals, probably just left off for demo purposes to show its actually bearings, getting a bit OT but early 3 speed sturmey archrer hubs apparently had bearing inside the gears, these swapped to bushings later on, presumably for reliability. i could see this doing the same, (and then being no more efficient than a chain)https://cdn.hiconsumption.com/wp-content/uploads/2018/07/CeramicSpeed-Driven-Chainless-Drivetrain-01.jpg['img]

same here, I'm not mechanical engineer so that's why I'm saying it would be great if the experts take over this prototype.
About the 110-120 points of contact in the traditional chain, is incorrect. The points of contact are going to be all the teeth on the chainring, cassette and pulleys and what we've been learning in all the friction studies in the past is the more teeth or point of contact in the chain the less friction loss is caused (the load of the chain is spread over all points of contact of the circular object). This is why the pro riders have been choosing a 56 or even a huge 58 chainring and big cassettes for time trials since long ago.
With this new drive train, the load on the front ring is not going to be shared around half the ring anymore but reduced to a single point. Same thing on the back at the cassette. That's the part it's hard for me to believe. The next question that I can think of is, as all the load is focused on a single spot, that's going to produce quicker wear on the ring and cassette?? does it makes sense?

My understanding was that the frictional losses come from the articulation of the chain links; the bigger the cogs in the drivetrain (chainrings, cassette and jockey wheels) the smaller the range of motion your chain linkages have to articulate and thus the lower frictional losses you describe. The number of points of contact may help reduce load on those individual points of contact and thus help reduce the friction at each individual one, but I believe it's the range of movement that's the critical factor in total friction.

Key marketing subterfuge: they are claiming a savings of 3% of the total aero drag on the bike alone, not the bike + rider system, right? So 3% of the 20% or so of total drag that the bikes accounts for, or about a 0.6% savings on total drag. Call it about 2w, depending on the assumed speed.

Because the semi-circle in the "cheese grater" that the bearing roller fits into is not moving straight up and down, but rather in a circle, there will be sliding going on all the time. More so on the smaller "cogs".

There's also the concentric shafts of the drivetrain that are rolling around eachother. There will be at least two bearings in there (and of larger diameter) that will incur mechanical losses.

I'm not saying I know what the answer is, but there are definitely losses in the system.

I'm also curious about how shifting will work - meshing the roller to the next cog in the cheesegrater might be complicated and where the mechanism to actuate and control that will go. Will it be in the wind?

Also - what are the gearing ratios on that tested setup vs. the chain system - are they comparable? Seems odd to not even mention that.

---

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

Actually, with the conventional chain, the friction comes only as the tooth grabs the next link in the chain, slides into place and rotates the pin joint on the chain to the angle it will be at with respect to the next link when it gets onto the cog. Once the link is situated on the cog and goes around the circle, it's not sliding around and the pin joint is not moving. When it gets to the point of leaving the cog, it has to to a small rotation of the joint and slide off the tooth, but that is totally un-loaded so the friction there is very small. A chain drive is very efficient. Pretty hard to beat.

---

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

Similar to my post above, this description is not quite right. First the load is not evenly distributed among the teeth. The first couple teeth with engagement of the chain on the top of the cassette take almost all of the load on that end of the drivetrain. The load on each tooth reduces drastically after that, down to zero pretty quickly. Same thing on the chainring, but on the back side of the top of the ring..

The reason that larger cogs and chainrings have less friction is that the angle the link needs to be at with respect to its neighbors on the cog or ring is smaller as the number of teeth go up, so the amount that the link needs to pivot about the pin is reduced.

---

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

3% is bike and mannequin. The numbers of bike alone are a lot higher percentage wise.

---

Chief Marketing Officer,
CeramicSpeed

It is rolling friction. Sliding friction is removed and that is the novelty of using bearings. The driveshaft is not novel, this was invented in the early 1900's. The novelty of Driven is in the engaging mechanism and use of bearings.

---

Chief Marketing Officer,
CeramicSpeed

If 3% is bike+mannequin, how is the article claiming only an 8-second gain over 40km? 3% on bike+rider CdA is an astronomical improvement, and would likely buy you over half a minute.

That’s my thought as well. The 2w estimate I stated is perfectly congruent with 8 seconds per 40k with the 5 watts = 0.5 sec/k rule of thumb used around here.

And 3% of mannequin + bike in road position on a road bike is even higher than a TT rider/bike

No, sliding friction is not removed.
The cheesegrater is rotating in an arc around the rear axle.
The the bearings are rotating around a different axis.
There is absolutely no way that there is not sliding occurring at this interface.
Angling the bearings in a cone arrangement would help this (closer to an involute bevel gear arrangement) but that would only work in one gear, you would need a different angle for every gear ratio.

That still doesn't get rid of the fact that you're putting huge forces through a single tiny cartridge bearing that is externally unsupported and totally not designed for this application.

I'm curious to know how they can achieve shifting under load without hitting neutral or over-constraining it or having to use multiple sets of rollers for each gear ratio.

I like how they claim that you can change "chainring" size as a benefit, as though that isn't already a thing with chain drive and isn't massively compromised by the need to use a different length (i.e. new) shaft.

It's cute that they've tested at 100W and extrapolated to 500W.

etc.

As someone who knows bearings I'd actually be interested to hear hambini's input on this design...

 
Doh!, yeah i totally overlooked sliding from that dimension!