Durability Of Velocity Aerohead Rims In 20/24 Hole Drillings.

On Nov 9, 8:51*pm, Frank Krygowski wrote:
On Nov 9, 10:31*pm, DirtRoadie wrote:







No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor). *You as always want *to expound
on anything and everything. Please *SHOW me. Here you have taken your
hypothesis ans simply restated it as a conclusion. That's sloppy and
exactly what you find *so offensive when others do it.

Start here. We have two riders CLIMBING at constant speed. EVERTYHING
about them is identical except that one is carrying weight in a water
bottle that is equal to the amount his rims and tires are lighter than
the other rider's (That's to assume we are putting that mass at the
wheel perimeter)
Now taking into account the fluctuation in force/power in their
(identical) pedal strokes, (as exemplified here):http://www.trainright.com/assets/new...ockdiagram.jpg

Show me just what happens between these two riders with those
fluctuations. *In particular, address the microscopically higher
speeds you have noted.

And yes there are some minor glitches in this hypothetical -please
point those out if you see them. But please also try to stay within
the scope of what I have described as much as possible.

Look at this as an opportunity to add the "science" you always refer
to but rarely provide.
Thanks.

DR

DR: *I _did_ show you, whether or not you understood. *Whether riding
on level ground or ascending a hill as you described, the principles
are the same. *There are some slight differences in magnitude, but the
effects are the same.

Sure, you can say the aerodynamics are constant, if you want. *That's
an approximation which although not perfectly precise, is certainly
close enough to reality, given the tiny fluctuations in velocity. *If
we accept that, then the guy on the lighter wheels doesn't actually
lose ground. *The two riders would remain exactly side by side. *But
the lighter wheels do _not_ provide an advantage.

I don't know what part of the explanation you didn't understand, so I
can't clear up your confusion for you.

Maybe you can dig into one of Carl's favorite calculator sites and
plug in the numbers. *Let me know how it comes out.

No the principles are different. Not saying the result is different
but you make assumptions that are not necessarily justified. First
wind drag is lost energy and I am specifically trying to avoid that.
(The present discussion has nothing to do with the benefits of aero
equipment which are accepted and understood and it just muddies the
results of the weight analysis.) Second you use the term
"microscopically" (twice) as if it has a value. Small, yes, but not
zero and not equal for all values of microscopic .
And you use it once to define acceleration/increased speed when the
rider is that portion of the pedal stroke where he/she is providing
some quantity of forward propulsion which is MORE than the retarding
forces (Gravity, friction, air, acceleration) and you use it again
when the deceleration is the result of the retarding forces being
greater than the mere momentum of the bike and rider. You equate the
first "microscopic" with the second yet have not shown how that is the
case. It's just a quick "they're equal." It's nothing more than an
assumption to say that the power stroke is a nice even sinusoidal
curve.

Carl's (Tom Compton's) analytical tools are great as far as they go,
but they rely upon assumptions which whitewash over what I am focusing
on. Give it some thought. Seriously, see if you can come up with
something other than "it's too small to matter." That's an
engineering perspective, not a scientific one although the latter may
lead to the former once quantified.

I purposely did not use an "out-and-back time trial" analogy as you
did because there is no conservation of energy as is the case (at
least hypothetically) with an up-and-back climb.

DR

On Tue, 9 Nov 2010 19:31:13 -0800 (PST), DirtRoadie
wrote:

No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor).

[snip]

Dear DR,

Why do you think that you can skip the aerodynamics?

Cheers,

Carl Fogel

On Nov 9, 10:32*pm, wrote:
On Tue, 9 Nov 2010 19:31:13 -0800 (PST), DirtRoadie

wrote:
No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor).

[snip]

Dear DR,

Why do you think that you can skip the aerodynamics?

I can do anything I want. But seriously, I wanted to focus on the
wheel weight issue as related to power fluctuation in a pedal stroke
and use a hypothetical where air resistance was a negligible portion
of the retarding forces.

DR

On Nov 9, 10:01*am, Frank Krygowski wrote:

What about the two minutes' advantage, over 40k, for an aero wheel
setup compared to "conventional"?

Of all race types, aerodynamic advantage is likely to be most valuable
in a time trial. *It's a maximum effort, completely solo, against
(usually) nothing but the air resistance. That's been known for
probably 100 years.

But even that knowledge can turn into a fetish. *I remember a similar
discussion here, where one person was honestly claiming that you could
count on something like a 0.5 second advantage in a 40k TT based on
whether your pinky finger was tucked behind your ring finger or not.
Or was it about clipping your fingernails?

I didn't say anything about fingernails.

Aero advantage of finger position is an example of something that
never makes it out of the wind tunnel. *There are other advantages
(whether aero, or weight, or inertia) that may possibly show up in a
time trial or a match sprint, but get swamped by tactics and random
events in any crit or road race. *And only the most extreme advantages
(like going to a recumbent, or losing over five pounds) are going to
be perceptible in non-competitive riding.

We're back to the "swamped in the noise" argument.
I maintain that the little advantages never go away. They might be
small, very small, but they are still there, all the time.
Like losing a pound, even from the 180lb rider + bike package yields
whatever-- a second or three in a 40k ITT, is that the amount that's
been demonstrated here? It's still real, even if people are foolishly
clipping fingernails, etc. etc.

Isn't it obvious that _some_ level of theoretical advantage must
disappear into the noise? *If not, racers would be shaving their
entire bodies.

Well, that's another one of your rhetorical devices, to which I can
only say, I'm not talking about shaving or clipping fingernails. Pinky
in the wind? No, but, as alluded to in that old Jim Martin article,
doing a lot of work (some need lots more than others) IRT developing
an aero position *with power* will yield positive results, and
sometimes (often, usually) big ones.

For instance, there was a racer here back in the day, a guy who won
"something national on the track" against the names of the day--
attesting to "the motor"; he certainly had one. But something I used
to see him do in races, consistently, was to be the only guy in the
pack (that I could see at the moment) who was *not* pedaling, and
sometimes, the only one not pedaling hard, while we were flying along.
That's not "equipment aero" but it sure is aero, and it's real. He was
really good at sniffing out a draft, and he did it without causing
crashes, too, BTW. That mindset, in addition to the "little details"
is what, IMHO, the smart racers do.

Tech stuff is often just grounds for neutral (especially, in these
modern times, apolitical) conversation. One of the old, gone-away
regular posters here used to "go on" about that but for all his
smarts, I don't think he got that one. Just a for-instance, but he was
only one...
There is a component (intentional!) of "geekery" that is IMHO a
totally healthy part of a competitive drive. Part of it is plain old
snob appeal, showing off the income, "keeping up", etc. etc., but some
of it is getting those little advantages that are always there despite
"the noise".

And what about the racing
community-- smart, successful and competitive people who read
equipment comparison tests not directly funded by mfg's?

I know, and have known, members of the racing community. *As I said, I
was on a ride with two of them not long ago. *One was saying "I'm
thinking about trying those ceramic bearings for my crank." *Nice
guys, but that's not saying much for their technical judgment.

The ceramic bearing thing ran its course (semi-intentional!) around
here. I'm not in the inner circles of racing but gathering partly from
shop scuttlebutt, those bearings were perceived as having a smoother
feel in certain BB's (esp., outboard types) than stock parts, these
stock BB's being noted for not being very smooth, but the maintenance
turned out to be "stupid", to coin a phrase. That's all "reportage",
no personal experience here.

Sure, *everyone* is susceptible to suggestion; then you go "try it out
for yourself", or maybe let someone else try it out for you g.

Of course, here I may be writing to a bunch of guys who think ceramic
bearings will let them surge into the lead!

Maybe a few, but, again, what I see is, most of them are competitors
looking for an edge-- like going to a Driveway race where the field is
limited to 100 and you can expect a minimum of 50 to show up on a slow
night. There's a huge difference between those two mindsets.

D-y, it wasn't intended to be abusive - any more, I suppose, than your
phrase "which is usual for you."

Well, Frank, you do come off as being abusive. What can I say? Saying
so doesn't automatically make me abusive.

DirtRoadie has frequently gotten hot with me when I express skepticism
about the wonderful benefits of the latest marketing gimmick. *Based
on that, I take him to be a person who (like my sports-car friend) is
really, really into having the latest and greatest. *Like the guy
saying "God, I gotta get a carbon frame" at 1:43 inhttp://www.youtube.com/watch?v=Vn29DvMITu4

Maybe I'm wrong. *But if DR is really so much into high-zoot equipment
that he attacks engineering judgment as heretical, he _needs_ to buy
high-zoot equipment, and I'm not going to try to convince him
otherwise. *That was the meaning of my post.

You usually do better the second time around. Am I chiding? Yes, I am.
I'm not pretending to be innocent of poke-and-poke-back, either.
But, you'll notice, I working on consensus and getting things
straight-- or straighter-- here. I hope that's what comes off.

I don't think it's stupid to look for those small advantages. Not
doing a total body shave might actually translate to "looking for
small advantages that are real", if you think about it that way. And I
should add, when I talk about these local racerdudes, part of the
background is that many (most, nearly all) are dedicated "trainers".
Some are a lot better at it than others, and some picked their parents
more carefully (check column A for Athleticism), but by and large
they, in addition to concern with "parts", also read up on training
methods and apply, with rigor. IOW, just to make sure this end of the
discussion is covered, so to speak, they're not a bunch of lazy
dumbells who expect to eat nachos and drink beer all week and then
have their ceramic bearings save them at the races.
--D-y

On Nov 10, 3:31*am, DirtRoadie wrote:
On Nov 9, 7:22*pm, Frank Krygowski wrote:

On Nov 9, 5:22*pm, DirtRoadie wrote:

On Nov 9, 2:54*pm, Frank Krygowski wrote:

...*I'm trying to realistically talk about
bicycle technology.

Yes, let's do that as you offered with regard to wheel mass and
acceleration within the context of power surges in a pedal stroke. *I
am particularly interested in the effect on speed.
Now I understand that _energy_ *is conserved, but that does not tell
the whole story. Energy is also conserved when doing an up-and-back on
a climb, but average speed nonetheless suffers (even assuming no air
resistance). So starting there, would you like to do some comparing?

OK, if you like.

First, let's note that energy is _not_ actually conserved while riding
a bicycle. *If it were, you probably wouldn't get tired. *Energy is
dissipated as heat, through various mechanisms. *Most of the time (in
racing, anyway) the biggest loss by far is through aerodynamic drag.

Aero losses are higher when the relative air speed (bike through the
air) are higher. *That's why the fastest time trials happen in still
air, not on days with winds. *You lose more fighting into a headwind
than you gain on the way back. *You also lose more energy to wind
resistance when you're speeding down a hill, compared with climbing
it, and the faster you go the more you lose. *That's partly why a
breakaway is much more difficult on a long downhill.

So how does this affect level riding with lighter or heavier wheels?
First, we must keep in mind that the differences between light wheels
and heavy wheels are, for any competitive bikes, pretty small. *The
percentage differences in total system (bike + rider) inertia are even
smaller. *A 153 pound rider on a 17 pound (total weight) bike with
three pound wheels has barely over 2% of his inertia due to the
wheels.

Still: *If rider A has lighter, lower inertia wheels than rider B, on
the high power portion of each pedal stroke, both riders are going to
accelerate very slightly, and rider A is going to accelerate
microscopically ahead of rider B.

But on the _low_ power portion of each pedal stroke, both riders are
going to decelerate very slightly ... and here it is: *Rider A will
_decelerate_ microscopically more than rider B. *Rider B gains during
that phase. *Why? *Because during the deceleration phase, the wheels
with more inertia will act to keep the bike going, to decelerate
less. *It's a flywheel effect.

Practically speaking, it all averages out during ordinary constant
speed level ground pedaling. *Rider A may be going 20 mph plus or
minus 0.01 mph (that is, an amplitude of 0.01 mph superimposed on a 20
mph average) while rider B may be going 20 mph plus or minus 0.008
mph, but the practical measurement of each rider's speed is still 20
mph. *There's no advantage to lighter wheels in that context.

But there's more. *Does it all average out perfectly? *No - and the
tiny differences in speed work to the disadvantage of the guy with
lighter wheels! *Here's why: *The guy with lighter wheels would get to
microscopically higher peak speeds. *Remember that aerodynamic power
losses vary with (actually, the cube of) relative speed. *During the
portion of the pedal cycle he's at 20.01 mph, he loses more energy
than his side-by-side competitor loses at 20.008 mph. *And like the
out-and-back time trialist on a windy day, he doesn't gain it back on
the other half of the cycle. *He'll have to be putting out
microscopically more power.

That's the physics. *In practice, it's all probably too small to
reliably measure. *That (roughly) 2% of inertia in the wheels is not
affected much by the switch to lighter wheels. *I mean, how much
lighter? *100 grams total? Then you're playing with maybe a tenth of a
percent of the total inertia. *Any effect of that difference will be
wiped out if, say, rider A has to wipe sweat out of his eye. *The
slightest vagary of breeze, bumps in the road, drafting a bigger rider
instead of a smaller rider, etc. will wipe out that difference.

"But what if I've trained perfectly, and I've done all I can do and my
training has reached a plateau. *Shouldn't I go with the lighter
wheels? *(Or maybe the more aero wheels?)

Personally, if it were me, I'd spend the money on other things. *A few
sessions on tactics with an excellent coach would probably kill any
wheel advantage you could buy. *As they say, knowledge is power.

No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor). *You as always want *to expound
on anything and everything. Please *SHOW me. Here you have taken your
hypothesis ans simply restated it as a conclusion. That's sloppy and
exactly what you find *so offensive when others do it.

Start here. We have two riders CLIMBING at constant speed. EVERTYHING
about them is identical except that one is carrying weight in a water
bottle that is equal to the amount his rims and tires are lighter than
the other rider's (That's to assume we are putting that mass at the
wheel perimeter)
Now taking into account the fluctuation in force/power in their
(identical) pedal strokes, (as exemplified here):http://www.trainright.com/assets/new...ockdiagram.jpg

Show me just what happens between these two riders with those
fluctuations. *In particular, address the microscopically higher
speeds you have noted.

And yes there are some minor glitches in this hypothetical -please
point those out if you see them. But please also try to stay within
the scope of what I have described as much as possible.

Look at this as an opportunity to add the "science" you always refer
to but rarely provide.
Thanks.

DR

PS- Love your consistency in ending "Personally, if it were me, ..."

The guy with the heavier rims climbs fastest, he drank his water 1/2
hour ago.

On Nov 10, 6:13*am, DirtRoadie wrote:
On Nov 9, 10:32*pm, wrote:

On Tue, 9 Nov 2010 19:31:13 -0800 (PST), DirtRoadie

wrote:
No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor).

[snip]

Dear DR,

Why do you think that you can skip the aerodynamics?

I can do anything I want. *But seriously, I wanted to focus on the
wheel weight issue as related to power fluctuation in a pedal stroke
and use a hypothetical where air resistance was a negligible portion
of the retarding forces.

DR

Rear wheel instability and inadequate chain lubrication are typically
the largest energy saps when climbing, and the inability to provide a
constant torque. Lower gears help..

thirty-six wrote:

Rear wheel instability and inadequate chain lubrication are typically
the largest energy saps when climbing,

Your home planet is full of marvels.

Chalo

On Nov 10, 1:13*am, DirtRoadie wrote:
On Nov 9, 10:32*pm, wrote:

On Tue, 9 Nov 2010 19:31:13 -0800 (PST), DirtRoadie

wrote:
No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor).

[snip]

Dear DR,

Why do you think that you can skip the aerodynamics?

I can do anything I want. *But seriously, I wanted to focus on the
wheel weight issue as related to power fluctuation in a pedal stroke
and use a hypothetical where air resistance was a negligible portion
of the retarding forces.

So what part of my explanation did you not understand?

Is it that you don't get that the inertia of a heavier wheel helps to
maintain speed during a deceleration phase?

- Frank Krygowski

On Nov 10, 1:40*pm, Frank Krygowski wrote:
On Nov 10, 1:13*am, DirtRoadie wrote:





On Nov 9, 10:32*pm, wrote:

On Tue, 9 Nov 2010 19:31:13 -0800 (PST), DirtRoadie

wrote:
No. Let get right down to it. Skip the aerodynamics (unless you just
want to make that a constant factor).

[snip]

Dear DR,

Why do you think that you can skip the aerodynamics?

I can do anything I want. *But seriously, I wanted to focus on the
wheel weight issue as related to power fluctuation in a pedal stroke
and use a hypothetical where air resistance was a negligible portion
of the retarding forces.

So what part of my explanation did you not understand?

Is it that you don't get that the inertia of a heavier wheel helps to
maintain speed during a deceleration phase?

You might want to address my reply to you rather than my reply to
Carl.

DR

On Nov 11, 3:26*am, " wrote:
On Nov 9, 10:01*am, Frank Krygowski wrote:

Aero advantage of finger position is an example of something that
never makes it out of the wind tunnel. *There are other advantages
(whether aero, or weight, or inertia) that may possibly show up in a
time trial or a match sprint, but get swamped by tactics and random
events in any crit or road race. *And only the most extreme advantages
(like going to a recumbent, or losing over five pounds) are going to
be perceptible in non-competitive riding.

We're back to the "swamped in the noise" argument.
I maintain that the little advantages never go away. They might be
small, very small, but they are still there, all the time.
Like losing a pound, even from the 180lb rider + bike package yields
whatever-- a second or three in a 40k ITT, is that the amount that's
been demonstrated here? It's still real, even if people are foolishly
clipping fingernails, etc. etc.

I agree with this.

If a tenth of a second can win a 40 km ITT, then 1h = 60min = 3600sec
= 36000 tenths of a second, and (1/36000) * 100 = 0.0027%

Not a big change necessary if it came down to it.

For instance, there was a racer here back in the day, a guy who won
"something national on the track" against the names of the day--
attesting to "the motor"; he certainly had one. But something I used
to see him do in races, consistently, was to be the only guy in the
pack (that I could see at the moment) who was *not* pedaling, and
sometimes, the only one not pedaling hard, while we were flying along.
That's not "equipment aero" but it sure is aero, and it's real. He was
really good at sniffing out a draft, and he did it without causing
crashes, too, BTW. That mindset, in addition to the "little details"
is what, IMHO, the smart racers do.

We've got one of those. I saw him actually hit the front of the bunch
a few weeks back and said "What's this? Can you feel the wind in your
face?" He smiled and replied, "Not for long."

The ceramic bearing thing ran its course (semi-intentional!) around
here. I'm not in the inner circles of racing but gathering partly from
shop scuttlebutt, those bearings were perceived as having a smoother
feel in certain BB's (esp., outboard types) than stock parts, these
stock BB's being noted for not being very smooth, but the maintenance
turned out to be "stupid", to coin a phrase. That's all "reportage",
no personal experience here.

I also draw a line between acceptable and unacceptable expense
required to make a measurable or perceived improvement in either
performance or reliability. I could afford to spend a whole lot more
on equipment, but I don't see the returns as they diminish quickly.

Sure, *everyone* is susceptible to suggestion; then you go "try it out
for yourself", or maybe let someone else try it out for you g.

Like outboard BB bearings. I reckon they're the bees knees. I used
to replace cartridges every year, now it's been about 4 years on the
same BB! I just regrease the bearings occasionally. As well, there
was a marked improvement in perceived BB stiffness. It felt like I
was riding a totally different frame. Whether or not it helped me go
faster, was probably lost in the noise though ;-)

Well, Frank, you do come off as being abusive.

I think Frank talks down to so many students, he talks to everyone
else the same. It's annoying. He knows not to whom he speaks.

James.