Track racing aero question

Rob said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish track) a
standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

This is a grossly over-simplified question, but a ballpark guess would
be helpful.

The aero bars make the greatest difference, so if you have those on the
trad bike I'd say the rest only saves 5-10 seconds.

Rob said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish track)

a

Quoted message said:

standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

This is a grossly over-simplified question, but a ballpark guess

would

Quoted message said:

be helpful.

Thanks,

Rob

Not as oversimplified as you may think...

I recall reading (in Winning magazine, I think) back when Rominger had
just broken the hour record on his round-tube'd Colnago, the question
came up about why he didn't use a bike similar to Boardman's Lotus
uber-bike. The response from his coach/trainer was that they had done
enough tests to determine that the difference in watts required to do
the speed required to break the distance, using his Colnago vs
Boardman's bike or one like it, was only about 4 more watts. They
didn't think it was worth the expense of building (or buying) a super
bike they didn't need.

They determined that as long as they could get Rominger into his
optimum power to drag TT position on his Colnago, they were plenty aero
enough to break the record, considering his power to drag ration. Heh,
they were right.

The position of the rider is the most important aero consideration,
followed by the wheels (and tires), then frame. From Rominger's
experience, the frame is pretty much an afterthought, as long as what
you're using isn't grossly un-aero (read: super fat tubes) and it
allows the rider to achieve his optimum position.

Rob said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish track) a
standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

This is a grossly over-simplified question, but a ballpark guess would
be helpful.

Thanks,

Rob

By optimising your wheels HED seem to claim there's up to 3 seconds
per kilometre to be saved. I doubt if any frame is worth more than 1
second per kilometre over a normal sized round tube. Worth having if
your Olympic title depends on a second or two in a 4k pursuit, but for
most of us using the money to take time off work for training would be
more effective.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Rob said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish track)

a

Quoted message said:

standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

This is a grossly over-simplified question, but a ballpark guess

would

Quoted message said:

be helpful.

Thanks,

Rob

Not as oversimplified as you may think...

I recall reading (in Winning magazine, I think) back when Rominger had
just broken the hour record on his round-tube'd Colnago

The bike that Rominger used for his official attempt on the record had aero
tubing.

Andy Coggan

"Kinky Cowboy" <[email hidden]> wrote in message
news:1105147229.3eadf79f2145566edbc55f6498dc39a7@teranews...

Quoted message said:

I doubt if any frame is worth more than 1
second per kilometre over a normal sized round tube.

Even the difference between two aero tubed bikes may be as great as 0.5
s/km:

http://www.biketechreview.com/aerodynamics/aero_frame.htm

Andy Coggan

"Rob" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish track) a
standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

Lots.

Andy Coggan

Andy Coggan said:

"Kinky Cowboy" <[email hidden]> wrote in message
news:1105147229.3eadf79f2145566edbc55f6498dc39a7@teranews...

Quoted message said:

I doubt if any frame is worth more than 1
second per kilometre over a normal sized round tube.

Even the difference between two aero tubed bikes may be as great as 0.5
s/km:

http://www.biketechreview.com/aerodynamics/aero_frame.htm

Andy Coggan

That's as maybe, but in that test the "less aero" frame had fatter
tubes than the Cervelo, which has tubes the same width as an old
school steel round tube frame. The small frontal area of normal sized
round tubes can produce less drag than supposedly "aero" shaped tubes
with larger frontal area.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Andy Coggan said:

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I recall reading (in Winning magazine, I think) back when Rominger had
just broken the hour record on his round-tube'd Colnago

The bike that Rominger used for his official attempt on the record had aero
tubing.

Andy Coggan

Here's a photo of Rominger's hour record Colnago from that Winning
Magazine article:
http://www.damonrinard.com/photos/colnagoromingershour.jpg

Not to split hairs with you, but I'd bet that while that tubing had a
slight aero profile, it had no discernible aero benefit. Not nearly a
pronounced-enough aero profile to be meaningful.

Andy Coggan said:

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Rob said:

HI,

Anyone have a guess about how many seconds slower (3k, slowish

track)

Quoted message said:

Quoted message said:

a

Quoted message said:

standard track bike with round tubes, 30mm vee rims, and aero bars
would be than a full on $10k carbon wonder.

This is a grossly over-simplified question, but a ballpark guess

would

Quoted message said:

be helpful.

Thanks,

Rob

Not as oversimplified as you may think...

I recall reading (in Winning magazine, I think) back when Rominger

had

Quoted message said:

Quoted message said:

just broken the hour record on his round-tube'd Colnago

The bike that Rominger used for his official attempt on the record

had aero

Quoted message said:

tubing.

Andy Coggan

"dianne_1234" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Andy Coggan said:

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I recall reading (in Winning magazine, I think) back when Rominger had
just broken the hour record on his round-tube'd Colnago

The bike that Rominger used for his official attempt on the record had
aero
tubing.

Andy Coggan

Here's a photo of Rominger's hour record Colnago from that Winning
Magazine article:
http://www.damonrinard.com/photos/colnagoromingershour.jpg

You need to bone up on your hour record history! ;-)

Rominger actually set the record twice: first covering 53.832 km on
10/22/1994, and then upping that to 55.291 km on 11/5/1994. The photo you've
provided is from the first attempt, which was done in semi-secrecy primarily
as a dry run. However, with my "official" qualifier I was referring to the
latter, during which he used a white Colnago built out of steel aero tubing,
as shown in the pic about halfway down this page:

http://www.53x12.com/do/show?page=article&id=31

Andy Coggan

"Kinky Cowboy" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The small frontal area of normal sized
round tubes can produce less drag than supposedly "aero" shaped tubes
with larger frontal area.

This is nonsense. The Cd of a round cross-section is much larger than that
of properly profiled one. Thus, to achieve the same reduction in drag as can
be achieved using aero tubing* a round-tubed frame would have to have a much
smaller frontal area. This would yield a frame of insufficient
strength/stiffness, which is why they do not exist.

*I am assuming that the tube profile is, in fact, "aero".

Andy Coggan

Regarding Rominger's white Colnago, "Scott" <[email hidden]>
wrote in message
news:[email hidden]...

Quoted message said:

Not to split hairs with you, but I'd bet that while that tubing had a
slight aero profile, it had no discernible aero benefit. Not nearly a
pronounced-enough aero profile to be meaningful.

Based on the CycleSport report on Rominger's bike and the picture shown
halfway down this page, I disagree:

http://www.53x12.com/do/show?page=article&id=31

Andy Coggan

Andy Coggan said:

"Kinky Cowboy" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The small frontal area of normal sized
round tubes can produce less drag than supposedly "aero" shaped tubes
with larger frontal area.

This is nonsense. The Cd of a round cross-section is much larger than that
of properly profiled one. Thus, to achieve the same reduction in drag as can
be achieved using aero tubing* a round-tubed frame would have to have a much
smaller frontal area. This would yield a frame of insufficient
strength/stiffness, which is why they do not exist.

*I am assuming that the tube profile is, in fact, "aero".

Andy Coggan

Your final assumption is where you're going wrong. As John Cobb has
demonstrated, some supposedly "aero" tubes actually have a lower Cd
when turned round to face the opposite direction to what the
manufacturer intended. The fact is, most "aero" tubing is "aero" in
cosmetic, not aerodynamic, terms

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Andy,

Keep in mind that we're talking about a couple of things here which you
seem to be overlooking. While any 'non-round' tube may be more aero
than a round tube, the question is whether it represents a large enough
improvement to matter.

Don't forget the incredible 'noise' in calculating aero drag for a bike
frame that the wheel and fork blades throw into the equation, as well
as the effect of constantly varying yaw angle for the wind. The
relative effect of the bike frame on the overall drag measurement for
the bike/rider combined is for all intents and purposes negligible.

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Andy,

Keep in mind that we're talking about a couple of things here which you
seem to be overlooking. While any 'non-round' tube may be more aero
than a round tube, the question is whether it represents a large enough
improvement to matter.

Indeed, that is the question.

Quoted message said:

Don't forget the incredible 'noise' in calculating aero drag for a bike
frame that the wheel and fork blades throw into the equation, as well
as the effect of constantly varying yaw angle for the wind.

Absence of evidence is not evidence of absense (IOW, just because noise in
the data prevents demonstration of a difference doesn't mean that there
isn't one).

Quoted message said:

The
relative effect of the bike frame on the overall drag measurement for
the bike/rider combined is for all intents and purposes negligible.

So you claim...yet with some careful field testing I was seemingly* able to
detect a difference between two AERO frames that would result in a ~0.5 s/km
time differential. The advantage of something like the Cervelo P2T over a
round-tubed frame would obviously be even greater. Now you might choose to
call 1-2 s//km "negligible", but I wouldn't.

*I say "seemingly" only because I did not conduct enough trials to claim
that there is a difference at the P=0.05 level of signifiicance. It
wouldn't, however, require an outlandish number of trials to do so, nor is
there any requirement that the alpha level always be set so high.

Andy Coggan

Andy Coggan said:

"Kinky Cowboy" <[email hidden]> wrote in message
news:1105575768.90c9ef371af73ae196f8689a19ae7ad9@teranews...

Quoted message said:

It's not a "logical" argument

Well, at least you admit that you're reasoning isn't logical.
Andy Coggan

If you still can't tell the difference between logical and rational,
you are the weakest link. Good night.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Scott answers-<< While any 'non-round' tube may be more aero
than a round tube, the question is whether it represents a large enough
improvement to matter. >><BR><BR>
<< Don't forget the incredible 'noise' in calculating aero drag for a bike
frame that the wheel and fork blades throw into the equation, as well
as the effect of constantly varying yaw angle for the wind. The
relative effect of the bike frame on the overall drag measurement for
the bike/rider combined is for all intents and purposes negligible. >><BR><BR>

And I say cynically, How Dare You, put reality into the equation!
All the marketing gurus will be ready to burn you at the stake!!

C'mon, an aero frame, a stiffer crank, a lighter wheel, a carbon oversized
handlebar will make you WIN like Lance!!

I'm just wornout by the gadgets today on bicycles. I thought a winter off would
help but geeez, the last conversation about power transfer on a hollowtech II
crank just killed me.

Andy, Sheldon, Mike how do you do it???

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Andy Coggan said:

"Scott" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Andy,

Keep in mind that we're talking about a couple of things here which

you

Quoted message said:

Quoted message said:

seem to be overlooking. While any 'non-round' tube may be more

aero

Quoted message said:

Quoted message said:

than a round tube, the question is whether it represents a large

enough

Quoted message said:

Quoted message said:

improvement to matter.

Indeed, that is the question.

Quoted message said:

Don't forget the incredible 'noise' in calculating aero drag for a

bike

Quoted message said:

Quoted message said:

frame that the wheel and fork blades throw into the equation, as

well

Quoted message said:

Quoted message said:

as the effect of constantly varying yaw angle for the wind.

Absence of evidence is not evidence of absense (IOW, just because

noise in

Quoted message said:

the data prevents demonstration of a difference doesn't mean that

there

Quoted message said:

isn't one).

Quoted message said:

The
relative effect of the bike frame on the overall drag measurement

for

Quoted message said:

Quoted message said:

the bike/rider combined is for all intents and purposes negligible.

So you claim...yet with some careful field testing I was seemingly*

able to

Quoted message said:

detect a difference between two AERO frames that would result in a

~0.5 s/km

Quoted message said:

time differential. The advantage of something like the Cervelo P2T

over a

Quoted message said:

round-tubed frame would obviously be even greater. Now you might

choose to

Quoted message said:

call 1-2 s//km "negligible", but I wouldn't.

*I say "seemingly" only because I did not conduct enough trials to

claim

Quoted message said:

that there is a difference at the P=0.05 level of signifiicance. It
wouldn't, however, require an outlandish number of trials to do so,

nor is

Quoted message said:

there any requirement that the alpha level always be set so high.

Andy Coggan

You're obviously VERY into time trialing (understatement of the year),
so it's not surprising that you're looking for every possible
advantage. If you think your "field testing" has shown an advantage of
..5s/km for one frame vs another, good for you. I can't even begin to
list all of the possible sources of error for your field test results,
but hey, if you want to believe, then believe.

Go buy a new frame/wheelset/handlebar/chain/aero seatpost/whatever...
it's only money.

Scott Hendricks said:

You're obviously VERY into time trialing (understatement of the
year), so it's not surprising that you're looking for every possible
advantage. If you think your "field testing" has shown an advantage
of .5s/km for one frame vs another, good for you. I can't even
begin to list all of the possible sources of error for your field
test results, but hey, if you want to believe, then believe.

It may also be from even slight winds that may not be readily
detectable that make a difference in an otherwise perfect comparison.
For that there are some interesting curves in:

http://www.sheldonbrown.com/brandt/wind.html

Quoted message said:

Go buy a new frame/wheelset/handlebar/chain/aero
seatpost/whatever... it's only money.

I'm for it. And who cares what the TT outcome is besides the rider.

Jobst Brandt
[email hidden]