wheel aerodynamic advantage

On Thu, 20 Nov 2008 09:20:08 -0800 (PST), Frank Krygowski
wrote:

On Nov 20, 8:11*am, " wrote:
On Nov 18, 9:20*pm, wrote:

Dear D,

Me, I'd slap on aerobars and see a bigger speed increase for less
money:
*http://www.kreuzotter.de/english/espeed.htm

defaults + drops * *= 19.3 mph
defaults + tribars *= 20.4 mph

Compare that 1.1 mph gain to the 0.4 mph gain predicted by Analytic's
calculator for the best aero wheels versus box-section 32-spoke
generics.

Just to remind people, the original poster wanted to know if he would
be able to feel the speed difference if he went from box 32 to $200
aero rims and later explained that he's trying to avoid dropping below
20.0 mph on long stretches on the flats.

In other words, he wasn't asking about racing margins measured in a
few seconds over an hour.

Well, in a way, "you got me there" but OTOH, *maybe the OP "got it"
that a speed advantage, perhaps greater than expensive, maybe fragile,
wheels can be had by using Pete Bars. I've never looked myself but
just guessing such bars are cheaper than light, aero wheels?

Those bars can be very cheap. Admittedly, I got mine on a terrific
sale, but I'm sure they were less than $40.

And if the OP asked the questions about such aero bars, I'd say he
could definitely feel the difference. My speed increase always seemed
to be a bit more than what Carl posted (perhaps 2 mph) and they are,
in some ways, more comfortable for me than riding the drops.

The clip-on bars cause both a big reduction in frontal area and a drop
in drag coefficient. It's very noticeable. They're undoubtedly the
most bang for the buck regarding air resistance.

But they're not for use in pack racing or training rides. And IME
you've got to be careful with handling until you're used to them. I
nearly hit a roadside mailbox the first time I used them in a time
trial.

- Frank Krygowski

Dear Frank,

Like you, many riders find that aerobars give a greater than expected
speed increase.

One explanation is that many riders start out with more wind drag than
the calculators assume for the no-aerobar rider, which is a polite way
of saying that their form wouldn't win any prizes in wind tunnel.

But that can't be true of RBT posters, whose form is flawless.

Another explanation is the new toy effect. It's darned hard for a
rider to hold himself back when he's put a new toy on the bike and
want to put it through its paces. Almost any new equipment shows
improvements because the engine is concentrating harder than usual.

But we know that RBT posters _always_ put out maximum effort, so that
can't be the explanation.

So let's fall back on the idea that some aerobars are better than
others (glad you bought the right ones) and add that the calculators
might be erring on the conservative side in this case.

Cheers,

Carl Fogel

wrote:
Me, I'd slap on aerobars and see a bigger speed increase for less
money:

and

A quick look shows aerobars for about $80 plus shipping at Nashbar:

But the "best" aero wheels were priced elsewhere in this thread at
$2,000, ten times the original poster's $200 budget.

Andresmuro has said in this thread that he does HIM's. That means it's a
pretty reasonable guess that he already has aerobars. After aerobars, a $100
rear wheel cover has pretty good bang for buck.

On Thu, 20 Nov 2008 12:32:31 -0700, wrote:

More seriously, most riders trying to stay above 20 mph on the flats
don't need aerobars or aero wheels. They can get better results just
by working on their form--there's a hell of a lot of rider sticking
out in the breeze.

If they can afford it, they should do all these things. It's simple
concept. Trying to improve in a variety of things.

On Nov 20, 10:20*am, Frank Krygowski wrote:
On Nov 20, 8:11*am, " wrote:





On Nov 18, 9:20*pm, wrote:

Dear D,

Me, I'd slap on aerobars and see a bigger speed increase for less
money:
*http://www.kreuzotter.de/english/espeed.htm

defaults + drops * *= 19.3 mph
defaults + tribars *= 20.4 mph

Compare that 1.1 mph gain to the 0.4 mph gain predicted by Analytic's
calculator for the best aero wheels versus box-section 32-spoke
generics.

Just to remind people, the original poster wanted to know if he would
be able to feel the speed difference if he went from box 32 to $200
aero rims and later explained that he's trying to avoid dropping below
20.0 mph on long stretches on the flats.

In other words, he wasn't asking about racing margins measured in a
few seconds over an hour.

Well, in a way, "you got me there" but OTOH, *maybe the OP "got it"
that a speed advantage, perhaps greater than expensive, maybe fragile,
wheels can be had by using Pete Bars. I've never looked myself but
just guessing such bars are cheaper than light, aero wheels?

Those bars can be very cheap. *Admittedly, I got mine on a terrific
sale, but I'm sure they were less than $40.

And if the OP asked the questions about such aero bars, I'd say he
could definitely feel the difference. *My speed increase always seemed
to be a bit more than what Carl posted (perhaps 2 mph) and they are,
in some ways, more comfortable for me than riding the drops.

The clip-on bars cause both a big reduction in frontal area and a drop
in drag coefficient. *It's very noticeable. *They're undoubtedly the
most bang for the buck regarding air resistance.

But they're not for use in pack racing or training rides. *And IME
you've got to be careful with handling until you're used to them. *I
nearly hit a roadside mailbox the first time I used them in a time
trial.

- Frank Krygowski- Hide quoted text -

- Show quoted text -

I already have aero bars in my tri bike and can feel the difference.

On Nov 16, 11:38*am, " wrote:

I am considering the neuvation m28 aeros. There are also a few other
wheels in the market with 30 mm rims and 24 aero apokes for less than
$200.

Opinions, advise?

When you read about "excellent warranty experiences", think about
turnaround time.

Let's put it this way, I have a friend with three Brand O (for Ooops
I Did It Again!) front wheels (or is it four?) because they warranty
in pairs after the rear hub flange cracks (again, and again, and
again?). One of those, right at the beginning of an expensive charity
ride, when he didn't have a spare available. "Great warranty!",
phooey. --D-y

On Nov 19, 7:10*pm, Tom Sherman
wrote:
Jay Beattie wrote:

I'm too lazy to review the entire thread, sorry -- but what is the
aerodynamic advantage of a rear wheel that sits behind your legs and
the seattube. *That article posted by richard suggests that an
ordinary high spoke count wheel is the stiffest laterally, and since
an ordinary high spoke count wheel can be light (but perhaps not that
aerodynamic), I'm wondering whether a not-so-aerodynamic rear wheel
really matters.

With a properly positioned rider and rear wheel, the disc wheel acts as
a "splitter plate" that helps to re-attach turbulent airflow. The drag
reduction is significant, e.g.
http://www.hamberg.dk/pix/hpv/nocom/nocom_03.jpg.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.

That bike cries out for a rider with a black bat suit and a cape. --
Jay Beattie.