Question to the aero gurus - "non aero" frame vs Cervelo S5 frame / fork / seatpost

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BRM
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by BRM

Has nothing to do with irony but all about integrity of data. When you are busy with precise information (data) you should be precise with translations. The given format is BIKES, then it's for more than one reason not right to alter one of them into a style. When you do such a wrong translation and connect a wrong image with it then you harm the integrity of the data AND make yourself unreliable. (Connected with this is that the hybrid bike of the (wrong)sample pic rides much smoother than a conventional Dutch bike)

Anyway, this topic is full of strange incomplete questions, guesses and assumptions.

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DamonRinard
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by DamonRinard

Hi Calnago,

I don't remember if it was VeloNews, do you happen to have a link?

Early WT tests weren't conclusive. We're learning that it's not easy to answer the question, disc or rim, because "all else equal" means two fully designed bikes, not one bike switching between disc or rim brake configurations. A bike optimized for one is by definition not optimized for the other. This is mainly due to component interactions, where the best shape of other bike parts is different depending on the brake type.

As we explore the new design freedom afforded with disc brakes, we're finding aero gains just where early speculation pointed: where rim brakes no longer interface with other parts. Namely the rims, fork, head tube, seat stays, etc.

Sorry I can't say more, I've probably already said too much!
Damon Rinard
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Calnago
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by Calnago

Hi Damon, for the life of me I can't remember the exact publication or forum and I couldn't come up with in in a quick search, but I did find a post where someone was referencing the quote I was referring to (and I can't verify for sure that he quoted correctly so apologies if it is incorrect but it does seem to capture the gist of what I recall)...

From Damon when people were asking about the P5 testing: "We just got back from a tunnel trip and it's not looking pretty for disc brakes... I can't reveal the numbers yet but I'll just say that adding a front disc brake and caliper to any "superbike" would add enough drag to make it slower than some road bikes... "

Does that ring a bell at all? By the way, your previous post says all I need to hear. No more explanation necessary, I get it.
And that makes total intuitive sense to me, yet now that we have discs and aero trying to coexist, the marketing guys will try to make it sound like discs don't really detract from aero at all... blah, blah, blah.

The thing is, in my opinion, discs are here, and whether I like them on the upper end road bikes or not, they will likely end up there, I get that. Maybe not on my bikes, but on a lot of other bikes. But the whole obsession with aero technology is a little overboard imo. And that is NOT to say that I don't think being aero is hugely important, because I do. However, the vast majority of aero benefit of the bike/rider combination comes from the rider's position, not the bike. That is to say, I believe if you put two equally fit and same size riders on two different bikes, one being a super aero machine, and the other a not so aero machine, and if the guy on the aero machine is in even just a slightly less "aero" position than the guy on the non-aero bike, well... the aero guy's bike is all for not, despite however much technology went into it. And outside of tt's and maybe triathlons, no one is riding around in that position the majority of the time, well maybe a very few, but they are certifiably crazy :). In fact, it's kind of funny to see some "aero" machines set up with stack of spacers and bars approaching saddle height.... why bother. I know I haven't said anything earth shattering new in my last paragraph, just preamble to my belief that at this point in the bicycles evolution, I'd rather future development concentrated on making disc brakes more road friendly, than trying to eek out another miniscule aero benefit. I like simple bikes that function well, first and foremost.
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by kgt

Dangerous words by Calnago (but true IMHO)...

DamonRinard
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by DamonRinard

Hi Calnago,

Calnago wrote:Does that ring a bell at all?


No, sorry. When I don't have firm numbers, I'm pretty careful about what I say.

...the marketing guys will try to make it sound like discs don't really detract from aero at all...


Not a problem if it's true.

...aero...position ... aero machine...


To quote JFT, "Can you do both? Is that allowed?"

And the guy with the bad aero position, one might argue, needs an aero bike even more! LOL!

Good perspectives Calnago, and good points, all. I think there is room for everything in this.

One last thing, and this is not intended for you in particular:

People may have different opinions, but facts don't depend on opinions.

I've changed my opinion plenty of times when facts warrant it. I hope others are open to that possibility too. It takes a long time for many people. I was a weight weenie soo bad for soo long as I slowly learned about engineering and testing and data.

Cheers,
Damon
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

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Calnago
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by Calnago

Agreed, and yes, facts are facts. And opinions, mine included, are subject to change as well when presented with logical arguments one way or another. But even facts can be argued or presented in a way that blurs the distinction between fact and fantasy. And that's why we have Marketers.
And can you really do "both" 100%? For instance, I don't think with today's state of the art that disc brakes don't compromise aero at least a little bit. And for the last however many years it seems like the smallest of tiniest amount of aero gains are "winning amounts". So, if you were a world class tt racer, would you want your time to be marginalized even the tiniest amount? Probably not I would guess.
For the rest of us, sure, we can accept compromise. I guess deciding on what that compromise will be is the ultimate question.
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by RyanH

Calnago wrote:That is to say, I believe if you put two equally fit and same size riders on two different bikes, one being a super aero machine, and the other a not so aero machine, and if the guy on the aero machine is in even just a slightly less "aero" position than the guy on the non-aero bike, well... the aero guy's bike is all for not, despite however much technology went into it.


For those not aware, I have a whole thread that validates that statement, one of the few conclusions that can be made from my 30 or so test runs.

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kgt
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by kgt

My dear RyanH for some reason your rigorous tests and data are not easily "accepted". Only tests and data provided by manufacturers and magazines are. I personally do not wonder why...

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cyclespeed
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by cyclespeed

DamonRinard wrote:
mbrider wrote:Specialized Tarmac SL4 with standard handbuilt clinchers 28/32 spokes / regular round bar / cables in the wind / standard brakes sticking out / regular pedals.

What would be the aero advantage of a Cervelo S5 with all the aero do dads (zipp 404s ~ 10 watt / Cervelo aero bar ~ 6 watt / SRAM Etap ~ 6 watt / TriRig front brake / EE rear brake ~ 2- 3 watt combined / aero pedals ~ 2 watt)

Would the aero advantage be 45 watts over the Specialized? 50 watts?

Lets keep this as a discussion about the bikes and not about position. Assume the same position can be achieved on either bike.


Yes, 45 to 50 Watts at 40 km/h is about right. Knock off about 1/3 if you're drafting.


50 Watts at 40km/h?

I am a light, low power rider; fast up hills, not so good on the flat into a wind.

My bike is an Sworks SL5 Tarmac, with fairly non-aero Corima 47's or LW Meilensteins (slightly better). That's about as far as the 'aero' part of the bike goes.

I estimate my FTP to be about 270W. So by changing to an S5 with 'ETAP' (6W really?!), I move up to 320W? I mean that would be fantastic, and whereas before I hang on to the big guys at 50km/h on the flat, now I could break away?! Have to say I find that hard to swallow, but if it can be rubber stamped true, I'm happy to give it a go!

Stalkan
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by Stalkan

I think I would err on the lower end of Damon's range, but He knows more than I, that's for sure. That being said, I would be inclined to think 25-35watts at 40kph would be entirely possible. However, even if it is "merely" 5 watts why wouldn't you take it? How much training at this point would you need to raise your FTP by 5 watts? Not saying to substitute parts for training, at all; however, if you can train and improve equipment/position, why wouldn't you?

So by changing to an S5 with 'ETAP' (6W really?!)


I thought I was crazy but when I went from SRAM Red to Di2 I noticed a difference. I believe those 6 watts are mostly the housing hanging out in the air. Versus Di2 I wouldn't think there any difference.

Dez33
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by Dez33

cyclespeed wrote:I estimate my FTP to be about 270W. So by changing to an S5 with 'ETAP' (6W really?!), I move up to 320W? I mean that would be fantastic, and whereas before I hang on to the big guys at 50km/h on the flat, now I could break away?! Have to say I find that hard to swallow, but if it can be rubber stamped true, I'm happy to give it a go!


No. A few figures from the Tour Test.

tarmac 231 watts
Venge 204 watts
Cervelo S5 205 watts

giant tcr advanced sl 229 watts
Propel 210 watts

And your tarmac spec above is better than the tour test tarmac spec.

SixThirteen
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by SixThirteen

Of course Damon has the best data going, wind tunnels etc... to add flavour from my own experience, from over 2.2M data points and various bikes, I offer you following:

Image

So I'm about 1.7kph faster on the S2. I've calculated W/kph but not normalised for power increasing with the square of the speed. Also some of the rides would be bunches, some solo, form may have changed, I've not allowed for hills and so on. So its not the most scientific analysis you'll see.

N= number of data points, basically seconds of moving riding, so you're seeing a summary of over 1.4M data points



DamonRinard wrote:
mbrider wrote:So my question is, all other things being equal ... what would be your guess as to the wattage savings - a new Cervelo S5 frame / fork / seatpost vs 2008 Trek Madone 5.5 frame / Easton EC90 SL fork / Trek seatmast?


If I remember correctly, maybe 25 Watts at 40 km/h.
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Dr.Dos
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by Dr.Dos

cyclespeed wrote:50 Watts at 40km/h?

I am a light, low power rider; fast up hills, not so good on the flat into a wind.

My bike is an Sworks SL5 Tarmac, with fairly non-aero Corima 47's or LW Meilensteins (slightly better). That's about as far as the 'aero' part of the bike goes.

I estimate my FTP to be about 270W. So by changing to an S5 with 'ETAP' (6W really?!), I move up to 320W? I mean that would be fantastic, and whereas before I hang on to the big guys at 50km/h on the flat, now I could break away?! Have to say I find that hard to swallow, but if it can be rubber stamped true, I'm happy to give it a go!

270W FTP is maybe good for for realistically 36-37km/h avg. Differences are not that dramatic there (in watts, not in time as slower riders get more gains out of aero stuff time-wise). A super aero-bike will give you 1km/h, maybe. The fun starts at 340W/42-43km/h.

Better invest in a helmet, a body-suit, optimize your positon, use the narrowest aero-shaped bar you can get comfortable with and a chinese 27mm front wheel with fast tires such as Turbo Cottons or Contis. Best bang for the buck.

istigatrice
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by istigatrice

Dr.Dos wrote:use the narrowest aero-shaped bar you can get comfortable with


So to derail this thread even more I'd like to ask about this point. Say I'm comfortable on 36cm bars, but I can only find 36cm bars in a round shape, would a 40cm aero bar be more aero than the round shape even if my position became slightly wider?

I've heard that aero bars make a difference, but in terms of ball park I'm not sure if the extra 2-4cm of width 'cancels' the aero effects of the bars (in which case I might as well stick with narrower bars). Any insights? For reference I believe a set of 3T aeronova bars are 38cm c-c so I'd be adding about 2cm of extra width to my position, I can't afford the Enve SES which would probably solve this issue for me.
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Dr.Dos
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by Dr.Dos

A local aero-guru who works with Protour and national teams estimates 5W saved with every 2cm less width based on track testing.

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