Is an aero frame beneficial? (light or aero bike faster?)

Discuss light weight issues concerning road bikes & parts.
cep111
Posts: 95
Joined: Sun Nov 20, 2011 9:50 pm

by cep111

Here is a link to the German Tour magazine wind tunnel tests of several "aero road" frames compared to a Cannondale big tube road bike.
It's meant to be viewed on ipads and kindles so give it a minute to load and then you can scroll through it like a book.

http://www.tour-magazin.de/services/qtr ... 7.html#/24

My guess is that "aero road" frames will become more popular as time goes by. I'd rather have the Cannondale for a criterium though. Companies are acting like Aero road frames are new when in fact Kestrel has been selling them for over a decade but mainly to the tri market. Felt and Scott are pushing this "new" catagory hard.

Courant
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by Courant

Getter wrote:For the clueless...what is the equivalent of 225gr of drag?

Is there some kind of example that the layman can relate to? :smartass:

...and so I take it Bonnen is using 303's this year?


225g of drag is roughly 30W. (power = force * distance/time = force * speed = 0.225*9.81*13.3, 13.3m/s ~= 30mph).

The "clean air" argument is a bit of red herring - yes, if you're drafting someone, you experience less aero force, but that still the main force you need to overcome, and a saving is a saving at the end of the day. The whole aero kit thing is a matter of relative advantage. Given a certain rider on a given bike, what's the effect of e.g. changing the wheels - what this boils down to is which set of wheels do I take to race. What thisisatest says is spot on.

A final other point, despite the perception, your average consumer buys kit based on marketing, not engineering. However, the situation is reversed when it comes to pro-teams selecting equipment. Zipp et al are not going to release full aero data to the man on the street - I can, however, quite imagine them doing so, and providing comparisons to competitors, to a pro outfit. Best judge then of true effectiveness is what pros are riding.

by Weenie


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ras11
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by ras11

If you ride a small frame (50-53cm), you'll find aero frames to be a little silly. Getting water bottles in and out of a small Cervelo/Felt/Specialized/Litespeed/etc.. is a real joke. Not to mention that most aero designs are not based on bottles be present (except maybe the Scott/Neilpryde/Litespeed/S5). The only frameset (for smaller people) that even looks reasonable from a water bottle perspective is the Scott and maybe the Neilpryde. All the rest seem impractical (outside a TT event).

I would think that an aero fork will get you ~50% of the drag reduction over a standard vs.aero frameset with water bottles. If I were thinking to upgrade my ride, I would look a well fit/low weight/good handling frame, and swap out for an aero fork. Best of both worlds I suppose.

I don't think it’s fair to discount the clean/dirty air argument so easily. Drafting is an important element in cycling. The effect is that it changes the relative wind speed, such that higher yaw angles are (more) important. Take wheel designs for example, a stall angle of 15 degrees becomes much less appealing than lower profile aero wheels when wind speeds are (relatively) low. The same could be said for framesets. The existence of very large surface areas often leads to low stall yaw angles (i.e. Cervelo S5), which might not be an benefit in a drafting/pack scenario.

If I were shopping around for a aero bike, I think I would look at the Scott Foil and Neilpryde twice. They just seems more useful for most racers. They might not have the lowest drag values, but the tradeoffs make them serious road bikes, not morphed TT bikes. Trying to mix TT and Road is like trying to mix a Cross frame and road. It’s possible, but you have to manage the tradeoffs.
:-) Toys-R-Us

airwise
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by airwise

justkeepedaling wrote:One word for that, cobbles. The Venge is not the most comfy bike out there ;)


One word for that, cobblers :wink:

The SL4 is no more comfortable than the Venge and stiffer in many areas. If it's comfort he wanted he had the Roubaix.

Or are you saying that the aero advantage is only present on super smooth roads? I note that Tour couldn't even use a human being or attach the dummy's hands to the bar as the vibration EVEN in a wind tunnel would skew the results sufficiently to make them worthless...

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Getter
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by Getter

Courant wrote:
225g of drag is roughly 30W. (power = force * distance/time = force * speed = 0.225*9.81*13.3, 13.3m/s ~= 30mph).


Thanks for that...I think. :mrgreen:



airwise wrote:
justkeepedaling wrote:One word for that, cobbles. The Venge is not the most comfy bike out there ;)


One word for that, cobblers :wink:

The SL4 is no more comfortable than the Venge and stiffer in many areas. If it's comfort he wanted he had the Roubaix.

Or are you saying that the aero advantage is only present on super smooth roads? I note that Tour couldn't even use a human being or attach the dummy's hands to the bar as the vibration EVEN in a wind tunnel would skew the results sufficiently to make them worthless...


Saw on a Venge Pro promo video saying that "stiffness" of the Pro is on par with the SL2. Not sure what the S-Works would compare to.

For the Paris Nice TT...the QS team rode SL4's. For a TT I figured they would be on a Venge. I guess for a uphill TT...stiffness is more important?

The only time I see Roubaix's come out is well...Roubaix. :D

Courant
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by Courant

ras11 wrote:I don't think it’s fair to discount the clean/dirty air argument so easily. Drafting is an important element in cycling. The effect is that it changes the relative wind speed, such that higher yaw angles are (more) important. Take wheel designs for example, a stall angle of 15 degrees becomes much less appealing than lower profile aero wheels when wind speeds are (relatively) low. The same could be said for framesets. The existence of very large surface areas often leads to low stall yaw angles (i.e. Cervelo S5), which might not be an benefit in a drafting/pack scenario.


This is a fair point, though I suspect the change in yaw angle is relatively small. (My back of envelope calc would be, given typical drag reduction of 25% while drafting, you could back off the change in onset velocity... too late for that, I may do this tomorrow!). My main beef is that quite a few people go, ah, a wind tunnel is clean air, the real world is dirty, this then invalidates wind-tunnel results, which is far from the truth, it's far more subtle than that. All this is not to say I'd necessarily advocate getting an aero frameset - I agree with you that a lot of the action is likely in the fork, and small but significant details, so you could get a lot of the bang without going the full hog.

Courant
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by Courant

PS the other point about clear-vs-dirty, drafting-vs-not is the non-linear performance response of the rider! I.e. it's likely far more significant to optimise the performance of the frame in clean flow, because this has maximum impact on rider performance. If you want to win a race, you've got to hit the front at some point ;-)

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carbon2329
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by carbon2329

cep111 wrote:Here is a link to the German Tour magazine wind tunnel tests of several "aero road" frames compared to a Cannondale big tube road bike.
It's meant to be viewed on ipads and kindles so give it a minute to load and then you can scroll through it like a book.

http://www.tour-magazin.de/services/qtr ... 7.html#/24" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;


The picture shows:
-no water bottles
-no bottle cages
-no cables
-no bartape
-no shifters
-no helmet
-no face

(I bet if you put those factors in, the results woudl be so jumbled that the benifits would be even more indecernable, as to negate any benifit of an aero frame)

Not to mention(again):
-a gillet
-changing wind conditions
-humidity/Temp.
-etc...etc....

I will retact (in a way) what I said earlier and change it (a little). At this time I don't believe the "research", because of what I pointed out, above. But if proper studies are done and show a REAL & DISCERNABLE difference then...I am on board with Aero :thumbup:

You can't show "evidence" (of Aero benifits) with faulty/ non-realistic research and "show" it is an advantage, when basic elements are excluded (like cables, bottles, cages, shifters,etc...)

Yes, the Aero frames, in this case might show as better, but without the componets which are required to use that frame (again...cables, bottles, A FACE) then is is worthless information.

It might as well be a comercial. :noidea:

I am not Anti-Aero, but "come on guys".

We are talking about & using math equations showing "exactly how many watts are saved",...
but we get this from "research" that shows a frame being tested with out cables, shifters, bottles, A FACE.
Last edited by carbon2329 on Sat Mar 31, 2012 3:05 am, edited 1 time in total.

shadwell
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Location: Gold Coast Australia

by shadwell

I presume the exclusion of these "elements" in the testing is validated in your opinion as relevent as you believe he "elements" will interact differently with the variable framesets, and therefore cannot be treated as a constant and omitted??

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carbon2329
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Location: Utah

by carbon2329

I see what you mean.

I guess what I am trying to say (and probably not very well) is that when all the various "elements" are included, is seems it could totaly eliminate any real benifit of any frame, as it is compared to another. Or make the tru benifits so small as to almost disprove its usefullness. (does that make sense)

I appreciate the scientific method shown, becasue they are trying to isolate the frame and "keep other things constant", but if those other things (elements) totally destroy the theorized benifit, then........

Something standing alone might be aero, but if you hang a bunch of things on it (bottles, a rider, shifter, cables), how can you say one frame is truely better.

Say you are determining if different skin suits are more aero than another:
Sure there might be a "measurable difference" between them (however small that may be), but if you have them wear a backpack on thier back and baby-carrier on thier front, and a helmet etc.....whats the the difference :noidea: :D
(yes, it might be measurable, but, WOW, it's probably tiny........real tiny)

I may come across as real intense on the subjest, but I'm not. These are just my thoughts. :D
It's just fun to talk (type) about it.

P.S. I'm excited about VN's article coming out. I hope it is usefull and has some actually good results.
Last edited by carbon2329 on Fri Mar 30, 2012 12:15 am, edited 1 time in total.

justkeepedaling
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by justkeepedaling

There are many reasons why I don't believe the Tour test was an accurate aero test, however, there are hundreds of tests out there, done by experts such as John Cobb, in a wide variety of tunnels, with all sorts of configurations. There are also people who have field tested aero bikes and directly compared results to other bikes. I don't understand why some people can understand that time trial bikes are an advantage, and yet an aero framed bike such as a Cervelo S5 which is just about as aero, cannot be. In fact, tests have shown that it has the same relative performance with water bottles and without.

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prendrefeu
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by prendrefeu

The benefit is there, but some of us are arguing that in a road race (non-TT) the benefits from aero are very low on the scale of importance or factors that would determine a result.
Exp001 || Other projects in the works.

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LouisN
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by LouisN

I know it's very subjective, but I just wanted to throw that in:

http://www.norco.com/news/630/tuft-wins ... norco-crr/

In that race, after a flat, Tuft had to change for his road bike, because he didn't have a TT backup bike...

Would that mean he'd have beaten Grabsch with a more aero bike ?...

Louis :)

lcoolb
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by lcoolb

@VNTech: that 141g of drag a Venge frame saves over a round tube frame, how many % of total drag is that?

by Weenie


hansonator69
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by hansonator69

prendrefeu wrote:The benefit is there, but some of us are arguing that in a road race (non-TT) the benefits from aero are very low on the scale of importance or factors that would determine a result.

:beerchug:
Slam your stem.

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