Weight Weenies

robeambro wrote: There's roughly 0.003 CdA difference vs the Tarmac, which equates to between 3-4 watts @ 45km/h..

On my own post I probably miss judged the 0.007 difference but clearly more in the 0.005 / 0.006 range than the 0.003.



The SSe3 will be below the 0.0075 weighted with yaw angles and the SL6 above the 0.008... now still have doubts on the configurations being compared. If done with aero cockpit on the sl6, that would be absolutely remarkable... if done with std bars... that still a great performance.


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C36 wrote: ↑

Mon Jun 17, 2019 3:47 pm

robeambro wrote: There's roughly 0.003 CdA difference vs the Tarmac, which equates to between 3-4 watts @ 45km/h..

On my own post I probably miss judged the 0.007 difference but clearly more in the 0.005 / 0.006 range than the 0.003.

The SSe3 will be below the 0.0075 weighted with yaw angles and the SL6 above the 0.008... now still have doubts on the configurations being compared. If done with aero cockpit on the sl6, that would be absolutely remarkable... if done with std bars... that still a great performance.


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Please excuse my horrible Snipping Tool skills on a Touch Pad. I am ashamed ay myself for publishing this.
Anyway, if those three dots on the y-axis represent 0.007, 0.0075 and 0.008, to me it seems that at most yaw angles, the difference vs the SL6 is more around .0003 to .0004...

Of course we could wait for the whitepaper, but why do that if I can publish some embarassingly ugly analysis

Oh and, I'm also a bit unsure as to the Tarmac tested, the very asymmetrical CdA profile seems to suggest they tested it w/ discs, but the SS Evo seems to be very strangely symmetrical in comparison.

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C36 wrote: ↑

Mon Jun 17, 2019 3:47 pm

The SSe3 will be below the 0.0075 weighted with yaw angles and the SL6 above the 0.008... now still have doubts on the configurations being compared. If done with aero cockpit on the sl6, that would be absolutely remarkable... if done with std bars... that still a great performance.

Is it that surprising? For all its dropped stays and D-shaped seatpost the Tarmac has a fairly conventional, almost completely round downtube. The sharp edged Foil/KVF type shapes on the photos of the new Evo look like the whole bike has had significantly more aero focus in the design. It'd be odd if it wasn't noticeably faster in the tunnel, IMO.

aeroisnteverything wrote: ↑

Mon Jun 17, 2019 3:22 pm

robeambro wrote: ↑

Mon Jun 17, 2019 3:04 pm

There's roughly 0.003 CdA difference vs the Tarmac, which equates to between 3-4 watts @ 45km/h. To be honest this would be somewhat remarkable only if they'd done an apple to apple comparison, but I doubt they did. Which would mean that, once you put an aero handlebar on the Tarmac, the difference would be non-existent.

Also, not sure why it says "BMC Roadmachine", shouldn't they have tested the Teammachine (which would also have lower stack and aero handlebars)? Another potential example of cherry picking.

Usual Emonda aero as a brick wearing a plastic shopping bag.

I know there are many fans of Trek bikes on this forum, and this is totally OTT for the tread but it just struck me: objectively speaking, Trek makes bad bikes. Their Madone, while very much aero, is very porky - to a point where I've not seen that many pros use them in races, and certainly not where any climbing is involved. And their Emonda is, as you say, aero as a brick - and so much so that even it's light weight cannot possibly overcome that drag disadvantage on most topographies, even for those who are not constrained by the minimum weight limit. It just seems like a slower choice than the competition either way. Maybe the Domane is good for the unique demands of the Roubaix, but that's about it?

I won't comment as much as I'd like cause it's super OT, but think of how little performance gain in terms of weight saving an Emonda offers going up a climb (which is probably completely offset by drag at all but the highest inclines), and how much this drag penalty exponentially increases while blasting down a (non-technical) descent.
How can it be so bad at aero, I wonder.

robeambro wrote:
Please excuse my horrible Snipping Tool skills on a Touch Pad. I am ashamed ay myself for publishing this.
Anyway, if those three dots on the y-axis represent 0.007, 0.0075 and 0.008, to me it seems that at most yaw angles, the difference vs the SL6 is more around .0003 to .0004...

Of course we could wait for the whitepaper, but why do that if I can publish some embarassingly ugly analysis

Oh and, I'm also a bit unsure as to the Tarmac tested, the very asymmetrical CdA profile seems to suggest they tested it w/ discs, but the SS Evo seems to be very strangely symmetrical in comparison.

Well I didn’t manage to do it from the phone :p
But looking at the left scale where you put 0.0075 is 0.008.



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C36 wrote: ↑

Mon Jun 17, 2019 4:56 pm

robeambro wrote:
Please excuse my horrible Snipping Tool skills on a Touch Pad. I am ashamed ay myself for publishing this.
Anyway, if those three dots on the y-axis represent 0.007, 0.0075 and 0.008, to me it seems that at most yaw angles, the difference vs the SL6 is more around .0003 to .0004...

Of course we could wait for the whitepaper, but why do that if I can publish some embarassingly ugly analysis

Oh and, I'm also a bit unsure as to the Tarmac tested, the very asymmetrical CdA profile seems to suggest they tested it w/ discs, but the SS Evo seems to be very strangely symmetrical in comparison.

Well I didn’t manage to do it from the phone :p
But looking at the left scale where you put 0.0075 is 0.008.



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definitely agree on that. SL6 at zero yaw is right at 0.008 in cannondale's test. Cannondale's new bikes no doubt test well, but my skepticism stems more from the fact of competitor results they test than what their own bikes are doing. From independent tests it's pretty well confirmed that the ugly duckling systemsix is the fastest, but it was very minimally faster than the madone SL9 and venge vias in tour mag tests vs what cannondale showed to be quite significant improvement in their white paper.

if the SSE3 can return independent results within 10 watts of the supersix, then cannondale has a winner. problem is that cannondale's own charts are showing a performance gap bigger than that.

The F10 still appears to, quite comfortably, still be the leader in aero performance for non-specific aero / grand tour bikes.

C36 wrote: ↑

Mon Jun 17, 2019 4:56 pm

robeambro wrote:
Please excuse my horrible Snipping Tool skills on a Touch Pad. I am ashamed ay myself for publishing this.
Anyway, if those three dots on the y-axis represent 0.007, 0.0075 and 0.008, to me it seems that at most yaw angles, the difference vs the SL6 is more around .0003 to .0004...

Of course we could wait for the whitepaper, but why do that if I can publish some embarassingly ugly analysis

Oh and, I'm also a bit unsure as to the Tarmac tested, the very asymmetrical CdA profile seems to suggest they tested it w/ discs, but the SS Evo seems to be very strangely symmetrical in comparison.

Well I didn’t manage to do it from the phone :p
But looking at the left scale where you put 0.0075 is 0.008.



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You're right. I have embarassed myself with those drawings for nothing

Well, that would bring the difference to 6-8w vs the SL6. Which could be nearly erased by aero handlebars (assuming the latter was tested as it comes out of the box).
Not to mention that at a much more humane 35km/h average, the difference is already 3w as it is now.

Basically, from what I see it, and with all the assumptions we've made re: the test procedure, it's great to see the aero boundaries being pushed, but ultimately there's really little reason from an aerodynamic perspective to prefer one of these great bikes to the other. Aside from the Emonda. That one is aero-rubbish.

I just purchased a 2019 SS HM Disc frame at half the retail price - I love a good bargain………, you can find something good in almost anything if you look hard enough

robeambro wrote: ↑

Mon Jun 17, 2019 4:33 pm

How can it be so bad at aero, I wonder.

There's a few reasons.

They tested the H2 Emonda SLR, which is taller than every other bike in the test.

The DT is a flattened oval. The TT is sloping. The HT is extremely fat. The ST is rectangular with rounded corners. The seatmast is a cylinder. The Emonda SLR comes with the shallowest wheels: Bontrager XXX 2s at 28mm depth. The Emonda SLR has more exposed cables...the front brake hose is completely external, attached to the fork with zip ties.

In addition Trek has publicly admitted that the Emonda SLR spent ZERO time in wind tunnel testing. They may have done CFD but it's obvious aerodynamics was not a goal for the current model. Next years Emonda SLR will probably fall into line with current aero expectations.

The Emonda is indeed a sail.

Next years model is not going to change much. Maybe 2021?

The Emonda also looks very weird, is it just me that thinks it looks like it hit a wall head on a few times? I don't know if it's the headtube shape or the old school curved fork but from the side, it looks like the headtube angle is over 80° or something. I wonder what the studying of the brand of philosophy of aesthetics science would say...

mr2scott wrote: ↑

Tue Jun 18, 2019 12:42 am

The Emonda is indeed a sail.

Next years model is not going to change much. Maybe 2021?

MY2021 should be released in the summer of next year.

Dan Gerous wrote: ↑

Tue Jun 18, 2019 12:54 am

The Emonda also looks very weird, is it just me that thinks it looks like it hit a wall head on a few times? I don't know if it's the headtube shape or the old school curved fork but from the side, it looks like the headtube angle is over 80° or something. I wonder what the studying of the brand of philosophy of aesthetics science would say...

It's the H2 geo I think? H1 Emondas look less like a pooping dog and I wonder how much that extra ~3cm of stack height hurts in terms of aerodynamics.

Compare:

My comment was purely cosmetic, the Emonda just looks wrong to me, H1 is better but still looks like something is off.

I think what hurts the emonda being aero is the downtube is basically 90mm wide.

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mr2scott wrote: ↑

Tue Jun 18, 2019 5:41 pm

I think what hurts the emonda being aero is the downtube is basically 90mm wide.

It’s the shape more than the width. It’s ovalized...on the worst axis.