smooth road vs not so smooth
Mark Cleary
this observation on the road surface. Since I ride a road bike I tend to
not simply relax and ride I do it more for the training and workout so
speed is a factor.
Wind of course is the killer but I notice that on the country roads that
are asphalt the surface smoothness varies. It is almost as if the
smoother the road even in adverse conditions the bike goes much better.
I don't even mind a bit of a headwind if the road surface is especially
smooth. Sometimes even with a tailwind and downhill if the road surface
is not real smooth it is worse than a flat smooth road.
Now I don't want to go out into killer winds but given a basic ride I
prefer a really smooth pavement over almost anything else. I don't mind
the cold below 45 degrees if the road surface is nice. What factor does
the road surface come into play, is there anyway to determine this since
it is hard to define?
--
Deacon Mark Cleary
Epiphany Roman Catholic Church
Clive George
Do you remember some threads from last year about tyre sizes? Smooth
tarmac is definitely faster. If you've got a lumpy stone chip surface, a
larger tyre will probably be faster than a little one - absorbing the
lump rather than moving your bike and you up and down is good.
Don't know actual numbers though I'm afraid.
Frank Krygowski
The discussion on tire width and its relation to road roughness was
related to the test in Bicycling Quarterly magazine, Vol. 5 No. 1,
Autumn 2006 http://www.vintagebicyclepress.com/contents.html
The author's main point is that super-narrow, super-hard does not give
the lowest rolling resistance. Tires need to provide some suspension,
to avoid wasting energy by bouncing the bike+rider.
It certainly seems reasonable that optimum tire width and pressure
vary with road roughness. For examples at the extremes:
a) If you were riding on a smooth concrete floor surfaced with
perfectly smooth tile, you'd probably get minimum rolling resistance
by taking your tires off and riding on the bare rims. No need for
suspension, and no losses due to flex in the tire rubber.
b) OTOH, I recall finishing a mountain bike ride with a one mile run
on some super-coarse railroad ballast, consisting of limestone gravel
averaging at least 2" to 3" diameter. The riding was dreadful until I
let so much air out of my tires that my friend was convinced I'd pinch
flat. But I didn't flat - I just floated over the stones on about 20
psi, and the ride was very much easier.
As far as measurements of road roughness, I've never heard of one, but
it should be possible. For an analogy, there are several ways of
measuring the roughness of a cast or machined metal surface. The
classic ones used something analogous to a phonograph needle (remember
those?) dragged over the surface, with electrical output of an
attached transducer displayed on a meter.
I'd think about a rig towed behind a bike or car, that rolled (say) a
skateboard wheel down the road, and electronically measured its bounce
motion. Could be an interesting project for a motivated geek.
(And motivated geeks are probably responsible for most of human
knowledge!)
- Frank Krygowski
landotter
> Now that I have been biking the past 2 years a bit more serious I have
> this observation on the road surface. Since I ride a road bike I tend to
> not simply relax and ride I do it more for the training and workout so
> speed is a factor.
Delusional. Effort is what gets you fitness. And a touch of moxie. The
strongest riders I know around here, like my friend S., do things like
pull child trailers across town with single speed mountainbikes
mounted with 2.3 knobbies.
You want to smooth out your roads and get fit? Mount a Surly
Crosscheck with some 50mm Schwalbes at 40psi and every route is
perfect. You'll take a speed hit on the finest roads, but you'll never
say no to the rougher options. Again--if you think that velocity is
going to make you stronger--you're wrong. Take off the computer and
ride more.
Clive George
> Delusional. Effort is what gets you fitness. And a touch of moxie. The
> strongest riders I know around here, like my friend S., do things like
> pull child trailers across town with single speed mountainbikes
> mounted with 2.3 knobbies.
Bike riding should be fun, and for a lot of us increasing the fun
element is the most important bit to doing more of it and working harder
at it. So while there are some people who can gain fitness from pulling
a plodding bike along, others will gain more from a faster bike.
(though I've observed I gain the most from a couple of weeks in the
mountains...)
DougC
Asphalt itself is sticky too, if the temperatures are even moderately warm.
In my area there's a couple rural roads that are poured concrete their
entire distances. If the outdoor temperature is much over 75F, I can
immediately tell the difference when I roll from one surface to the
other, on any bicycle I've ever had.
~
David Scheidt
:As far as measurements of road roughness, I've never heard of one, but
:it should be possible. For an analogy, there are several ways of
Pavement geeks care about pavement smotoothness. Quita lot, actually.
There are all sorts of methods for measuring it, ranging from rolling
wheels, to inertial measurement and laser rangefinders. One of the
reasons that they care is that smooth roads last longer. Given two
stretches of pavement that are nominally the same (same subsurface,
same thickness of pavement, same paving materials, etc) the smoother
one will require less annual fixing of potholes, cracks, and so on,
and will have a longer service life. The other is that smooth roads
save fuel. There's an index called the "pavement servicability
index", which ranges from 0 (bombed out pavement) to 5 (perfect).
Roads are generally constructed to be about 4 or 4.5 (though it's
rarely specified that way in the contract, but by other defect
limiting clauses). A car travelling on a road with a PSI of 2 (which
is generally when they're replaced) uses
about 10% more fuel than it does travelling on a raod with a psi of 4.
For trucks and buses, the fuel consumption increase is higher. There
are also increased costs in tire wear, suspension wear, etc.
I don't doubt that bicyclists would experience the same thing.
:measuring the roughness of a cast or machined metal surface. The
:classic ones used something analogous to a phonograph needle (remember
:those?) dragged over the surface, with electrical output of an
:attached transducer displayed on a meter.
:I'd think about a rig towed behind a bike or car, that rolled (say) a
:skateboard wheel down the road, and electronically measured its bounce
:motion. Could be an interesting project for a motivated geek.
:(And motivated geeks are probably responsible for most of human
:knowledge!)
:- Frank Krygowski
--
sig 40
Mark Cleary
in really long time of training without the wear and tear. I can still
run a marathon in under 3:45 approaching 50 years old so I get a work
out. I would like to see how fast I could do a century. I could do one
solo in under 5:20 but I really don't know about a 5 hour Century maybe
if I had a pacer and some support team. I also need to find the
smoooooothest roads too.
--
Michael Press
<6e48f6fa-20dd-446f...@i31g2000vbt.googlegroups.com>,
landotter <land...@gmail.com> wrote:
> On May 17, 7:17 am, Mark Cleary <mclear...@comcast.net> wrote:
> > Now that I have been biking the past 2 years a bit more serious I have
> > this observation on the road surface. Since I ride a road bike I tend to
> > not simply relax and ride I do it more for the training and workout so
> > speed is a factor.
>
> Delusional. Effort is what gets you fitness. And a touch of moxie. The
> strongest riders I know around here, like my friend S., do things like
> pull child trailers across town with single speed mountainbikes
> mounted with 2.3 knobbies.
You confuse fitness with strongest.
Some people are born stronger.
Anybody can be fit.
Does not matter how hard I trained,
I never got as fast or strong as the born athletes.
--
Michael Press
Tim McNamara
Mark Cleary <mcle...@comcast.net> wrote:
It's not hard to define. The coarser the road surface, the more energy
it takes to maintain the same speed. The energy require escalates
rapidly as the road surface gets rougher. A smooth grained road is much
easier to ride than one that's been chip-sealed with 1/2" aggregate and
tar. Or try riding on cobblestones to really see the effort level go
up, or the "wake up" strips on the shoulders of many roads. With
something like an SRAM PowerMeter or a Tune PowerTap, you can measure
the difference quite conveniently.
Fatter, lower pressure tires reduce this effect dramatically and the
energy required to maintain a given speed is much lower. And, much to
many people's surprise, those tires can also be faster on smooth
pavement. Skinny high pressure tires are not necessarily faster.
There's a lot of data about this but many people refuse to accept it.
carl...@comcast.net
<mcle...@comcast.net> wrote:
>What factor does
>the road surface come into play, is there anyway to determine this since
>it is hard to define?
Dear Mark,
A good deal of what riders perceive as a striking difference in speed
on rough and smooth roads is actually just the difference in the sound
that we hear and the road buzz that we feel.
Our ears and fingers are sensitive enough to tell the difference
between rough and smooth pavement, which we tend to conflate with an
ability to judge speed differences of ~3% at ~25 mph while just riding
around.
In other words, very few of us would believe that we would instantly
notice a 5 inch rise in 100 feet or a sub-2 mph headwind at ~25 mph
without a cyclocomputer, but either of them will quietly reduce our
speed about the same 1 mph as moving from smooth to rough pavement.
As a rough guide (sorry, couldn't resist it) . . .
Coefficient of Rolling Resistance.
Wooden Track 0.001
Smooth Concrete 0.002
Asphalt Road 0.004
Rough but Paved Road 0.008
http://www.analyticcycling.com/ForcesSpeed_Page.html
Plug in those values for the defaults and a level 0.00 slope instead
of the 3% default . . .
Wooden Track 0.001 11.64 m/s 26.04 mph 103.7%
Smooth Concrete 0.002 11.50 m/s 25.73 mph 102.4%
0.003 11.36 m/s 25.41 mph 101.2%
Asphalt Road 0.004 11.23 m/s 25.12 mph 100.0%
0.005 11.09 m/s 24.81 mph 98.8%
0.006 10.96 m/s 24.52 mph 97.6%
0.007 10.82 m/s 24.20 mph 96.3%
Rough but Paved Road 0.008 10.69 m/s 23.91 mph 95.2%
In other words, your speed might vary 3~4% from a normal asphalt road,
+/- ~1 mph from 25 mph, depending on whether you find a good wooden
track or can't escape some bad chip seal.
(A _really_ rough road will be even worse, but this is just a rough
guide. What could be called the jiggle factor could make things worse,
but it's awfully hard to figure out how much each rider jiggles.)
With another calculator, we can make a rough comparison of such small
differences with the effect of the wind by putting in 301.46 watts,
tubulars, and drops:
http://bikecalculator.com/veloUS.html
(Yes, you have to adjust watts between calculators--the difference
lies in the defaults and how many tiny factors are included.)
same
speeds
as above wind
wood 26.04 mph -1.43 mph tailwind
concrete 25.73 mph -0.96 mph
25.41 mph -0.46 mph
asphalt 25.12 mph 0.00 mph no wind
24.81 mph 0.48 mph
24.52 mph 0.94 mph
24.20 mph 1.45 mph
rough 23.91 mph 1.91 mph headwind
Winds below 2 mph are practically undetectable without resorting to
instruments or dropping dust and watching which way it drifts--it's
just the breeze on your face at about half normal walking speed in a
quiet hallway.
We can also compare the effect of roughness to the effect of very
gentle climbs and descents:
same
speeds
as above grade
wood 26.04 mph -0.337%
concrete 25.73 mph
25.41 mph
asphalt 25.12 mph 0.00% grade
24.81 mph
24.52 mph
24.20 mph
rough 23.91 mph 0.442%
A grade of 0.337% is only ~4 inches in 100 feet, as opposed to a grade
of 3.000%, or 36 inches in 100 feet, while a grade of 0.442% is only
~5 inches in 100 feet.
Of course, altitude can help:
28.32 mph ~8,750 feet Telluride, CO
27.64 mph ~7,000 feet Santa Fe, NM
26.89 mph ~5,000 feet Pueblo, CO
same altitude
speeds above
as above sea level
wood 26.04 mph 2669 feet
concrete 25.73 mph 1810 feet
25.41 mph 902 feet
asphalt 25.12 mph 75 feet
24.81 mph
24.52 mph
24.20 mph
rough 23.91 mph
I ride at about 5,000 feet above sea level, a very modest altitude for
Colorado--that improves the predicted speed to 26.89 mph, better than
a wood track.
Cheers,
Carl Fogel
MikeWhy
news:5274v5hhh80gcp8ht...@4ax.com...
So, has anyone tabulated the relative performance of MTB knobbies to light
racing slicks? I'm really more interested in the difference between 700x28
on crushed limestone paths, relative to 700x23 on "average" asphalt. Or
700x23 on the groomed limestone paths. How much difference is there between
wet and dry crushed limestone? Wet and dry asphalt?
Jay Beattie
Macadam and chip seal are miserable -- I rode a stretch through the
Ozarks on a hot day, and my wheels looked like chocolate nut sundaes.
The tar and gravel had filled the fenders, which I removed and
trashed.
Rough pavement is a drag, literally -- how much depends on the surface
and your tires. Unless you have a choice of routes, though, it is
simply a fact of life. If I were going on a chip seal adventure, I
would throw on some fattish road tires. -- Jay Beattie.
(PeteCresswell)
>So, has anyone tabulated the relative performance of MTB knobbies to light
>racing slicks? I'm really more interested in the difference between 700x28
>on crushed limestone paths, relative to 700x23 on "average" asphalt. Or
>700x23 on the groomed limestone paths. How much difference is there between
>wet and dry crushed limestone? Wet and dry asphalt?
I can't speak to those specifics, but on my rides to work
sometimes I ride 55/55 WTB Mutano Raptors (pretty fat... about
2.4", with modest knobs) at 40 psi on an FS.
Other times I ride a rigid with Performance 1.5" City STs at 60
psi.
I perceive the diff in max cruising speed to be between 1.5 and 2
mph.
I guess I should mount the WTBs on the rigid and see what I
get....
--
PeteCresswell
Michael Press
Tim McNamara <tim...@bitstream.net> wrote:
Most of the data is from road racers who ride narrow,
high pressure tires in all conditions. Until racer
preference is explained, lower energy dissipation of
wide, low pressure tires on roads is not proven.
--
Michael Press
David Scheidt
:In article <timmcn-A1029F....@news-2.mpls.iphouse.net>,
: Tim McNamara <tim...@bitstream.net> wrote:
Sure it is. That's what auto and truck tire makers, who care about it
a lot more than bike tire people, say. On a bike, though, air
friction is going to overwheml the difference at some point. I don't
know where the cross over point is, but I'd quess it's around 20mph,
which is where it is for so many things.
--
sig 95
Tim McNamara
Michael Press <rub...@pacbell.net> wrote:
Measurements trump racer preference. Measurements have been done.
carl...@comcast.net
<tim...@bitstream.net> wrote:
Dear Tim,
Did the measurements take place at racing speeds? Or with racer-level
pedal-effort?
I remember downhill coasting tests with motionless riders. With those,
I wonder if the artificial constraint of motionlessness exaggerates
what could be called the jiggle effect.
And racers may jiggle less than the rest of us. Lance Armstrong, for
example, may jiggle less than I do, since he's quite a bit lighter and
was constructed with far less insulating material.
The raw speed may also matter. Racers of various kinds of vehicles
often remark that the ride smooths out at certain speeds. Also, the
increased wind drag of wider tires, rims, and forks at racing speeds
may outweigh wide-tire advantages found at lower speeds, where rolling
resistance accounts for more of the total drag.
I vaguely recal idea that you've mentioned tests with power meters,
which would necessarily include normal motion, even if speeds were not
up racing speeds.
But I'm embarrassed to say that I don't remember any details of the
posts. Assuming that you made such posts (sorry if I'm just confused),
could you remind your more forgetful readers of the measurements?
Cheers,
Carl Fogel
Dan O
> Now that I have been biking the past 2 years a bit more serious I have
> this observation on the road surface. Since I ride a road bike I tend to
> not simply relax and ride I do it more for the training and workout so
> speed is a factor.
>
> Wind of course is the killer but I notice that on the country roads that
> are asphalt the surface smoothness varies. It is almost as if the
> smoother the road even in adverse conditions the bike goes much better.
Absolutely so. I regularly climb hills on some roads that are not
very smooth - roughest on the unworn paved shoulder, smoothest in the
worn tire tracks. It is like night and day trying to climb on the two
surfaces - much easier going on the smoother surface.
> I don't even mind a bit of a headwind if the road surface is especially
> smooth. Sometimes even with a tailwind and downhill if the road surface
> is not real smooth it is worse than a flat smooth road.
You know you're alive when you have bad road to ride uphill dodging
pieces of roadkill into a cold headwind and pouring rain with hostile
motorists blasting horns as they buzz your elbow :-)
>
> Now I don't want to go out into killer winds but given a basic ride I
> prefer a really smooth pavement over almost anything else.
Smooth is nice - to a point. (We get a lot of rain where I live ;-)
If all roads were smooth you would not have this appreciation.
Variety is the spice of life.
I know you don't need me to tell you this, but adversity is what gives
appreciation for the more favorable conditions, and I believe that
enduring that adversity is how the more favorable conditions might be
deserved.
I have a little spiritual exercise sometimes. When out riding and
coping with some adversity, I think to myself, "What if I had to face
this adversity forever to save someone I love?"
> I don't mind
> the cold below 45 degrees if the road surface is nice. What factor does
> the road surface come into play, is there anyway to determine this since
> it is hard to define?
I first learned to ride on a dirt road. It was hard packed clay, with
some bumps, but a smoother surface than any typical concrete sidewalk
or asphalt paved road. You just had to learn to pick a line.
I appreciate opportunities to ride in the greatest variety of
conditions. Sure, when I find myself on a rough road, I will always
look for the optimally smooth line (in part because it's easier on the
bike), but that is part of the experience. Yes, I think this is the
gist of it.
I think you have a very good philosophy about riding. Just felt like
sharing some of mine.
Michael Press
David Scheidt <dsch...@panix.com> wrote:
The measurements are of people riding a bicycle down an
incline on pavement outside in the wind. There are
temperature differences, humidity differences, and wind
differences the tester has to account for; but he did
not. He did not have a control bicycle that he ran
every time and correlated the times with temperature,
humidity, and wind speed so as to be able to remove
those effects from the tires of interest. He did not
run each tire at a variety of inflation pressures. I
conclude that the experiment did not do enough to
resolve differences among the tire; and drawing
conclusions from the report is an act of faith.
At this point the choice of racers is the best data we have.
I want to know how much power is dissipated from the
effects of rough pavement on various tires transmitted
to the rider; more than those who hang their hats on the
bicycle magazine bicycle roll down tests.
--
Michael Press
incredulous
> In article <hsv4un$96...@reader1.panix.com>,> > :In article <timmcn-A1029F.23532817052...@news-2.mpls.iphouse.net>,
> > : Tim McNamara <tim...@bitstream.net> wrote:
>
> > :> In article <hsrc55$rk...@news.eternal-september.org>,
I have only read Jan's seconday reports of the experimental design. I
wonder if he doesn't depend on a too-literal model of the riding
situation, what with real rider and bicycle. Maybe engineers in this
group could propose an inexpensive alternative to the roll-down tests.
For example, why use a bicycle at all?
Why not a simple remote-controllable two or three-wheel cart driven by
a small electric motor? Use one small motor to bring it up to a
specified speed, and then another small motor sustain the speed over a
course, measuring the power consumed. Run the cart in both directions
on a straight pretty-level road; or have it run in a repeatable circle
on a vacant parking lot. With pairs or triplets of tires of the same
type, between-sample error-variance contribution is reduced, and tire-
rolling resistance contributions to power-sucking will go further in
overwhelming air-resistance effects.
Replicate over different tires, surfaces, tire pressures, cart-weights
and speeds, as desired.
And except for the desired human company and help in changing tires,
this setup can be run by one person.
What's wrong with this design? If not much, how much might it cost to
to construct and instrument the several components of the cart
(without the donated CF wheels)?
Harry Travis
New Jersey,
USA
David Scheidt
:In article <hsv4un$96a$1...@reader1.panix.com>,
: David Scheidt <dsch...@panix.com> wrote:
No. They're not. I didn't mention bicycles. Not at all.
There are lots of good data by tire manufactures -- manufactures of
automobile and truck tires, not bike tires (though I'm sure the bike
tire manufactures have data too; they're just not sharing) -- that
show that increasing tire width reduces rolling resistance. The same
applies to bike tires as well; the physics isn't magical.
--
sig 7
z, fred
That's if both tires are at equal pressure. Most people who run wider
tires do so at lower pressures for the comfort factor, negating the RR
benefit.
David Scheidt
z, fred
Dumbass,
Get your grammar right. Who follows he, whom follows him. [He] said if
both tires are at equal pressure, not [Him] said...
Prove me wrong.
thirty-six
> In article <timmcn-A1029F.23532817052...@news-2.mpls.iphouse.net>,
> Tim McNamara <tim...@bitstream.net> wrote:
>
>
>
> > In article <hsrc55$rk...@news.eternal-september.org>,
23mm is generally accepted as minimum now, for those in the know.
Even 25mm HPs are being raced on without excessive rider weight.
thirty-six
> Michael Press <rub...@pacbell.net> wrote:
>
> : Tim McNamara <tim...@bitstream.net> wrote:
>
> :> In article <hsrc55$rk...@news.eternal-september.org>,
At 30mph in a chain gang on good road surface, there is no perceptible
difference in effort between 22 and 25mm. Although duration to
exhaustion may be quicker with the narrower tyre. There are complex
happenings due to vibrationary effects upon the body which although do
not limit maximum output tend to make the rider tire out quicker.
Michael Press
Tim McNamara <tim...@bitstream.net> wrote:
The best measurements I have seen prove
that narrow high pressure tires have less
rolling resistance than wide low pressure tires.
--
Michael Press
thirty-six
> In article <timmcn-0A1C19.17560718052...@news-2.mpls.iphouse.net>,
> Tim McNamara <tim...@bitstream.net> wrote:
>
>
>
> > In article <rubrum-2315EA.14452718052...@news.albasani.net>,
> > Michael Press <rub...@pacbell.net> wrote:
>
> > > In article <timmcn-A1029F.23532817052...@news-2.mpls.iphouse.net>,
> > > Tim McNamara <tim...@bitstream.net> wrote:
>
> > > > In article <hsrc55$rk...@news.eternal-september.org>,
really? like vwith like? same carcass constructiohn, same tread
thickness, same tread pattern, same rubber? Was the wider tyre a
more durable construction (heavier carcass, thicker tread, rubber
sidewalls) more suited to withstand continued abuse over rough roads?
Tim McNamara
Michael Press <rub...@pacbell.net> wrote:
There is other data that you should be looking at then, or perhaps which
you have looked at and rejected for some reason. The rougher the
pavement, the greater the benefit of wider softer tires. Heine, for
example, found ~200W differences on very rough pavement with the wider,
softer tire outperforming the narrower higher pressure tire using a
PowerTap hub as the measuring tool.
However, it is necessary to minimize the structural differences between
tires when making this comparison. Most wide tires also come with much
thicker rubber tread, coarse tread patterns, etc. They look more like
tractor tires than bike tires and weigh 3-4 times as much. Most tire
makers don't comprehend there is a market for wide high quality tires
with good casings, thin rubber and no tread patterns. There are fairly
few choices for wide high performance tires- mainly the Panaracer Pasela
and a few small label specialty tires (Brand Bois, Pacenti) and some
tires from Schwalbe (I am told the Kojak is a high performance wide tire
but I've never seen one).
Of course most road bikes can't manage a tire wider than 25 mm so it's a
moot point. I did many road races and crits on my 'cross bike with 700
x 32 Avocet Duros. Didn't slow me down at all and was great in fast
corners in crits and on descents.
carl...@comcast.net
<tim...@bitstream.net> wrote:
>There is other data that you should be looking at then, or perhaps which
>you have looked at and rejected for some reason. The rougher the
>pavement, the greater the benefit of wider softer tires. Heine, for
>example, found ~200W differences on very rough pavement with the wider,
>softer tire outperforming the narrower higher pressure tire using a
>PowerTap hub as the measuring tool.
Dear Tim,
Is the 200 watt differences a typo?
Cheers,
Carl Fogel
incredulous
Must be a typo.
But, at least one measurement tech or engineer responsible for testing
or reporting estimates of differences in coefficients of rolling
resistance writes that the differences under test greatly
underestimate the differences on the road.
Here are some published estimates of losses for a number of tires on
the standard smooth drum, for two loaded tires at 30k/h, about 18.5
mph.
http://www.rouesartisanales.over-blog.com/article-1503651-6.html
The difference between best and worst clincher pair of standard
22-25mm road racing tires was about 20 watts of energy loss.
Harry Travis
Pinelands of NJ
USA
Jobst Brandt
>>> There is other data that you should be looking at then, or perhaps which
>>> you have looked at and rejected for some reason. The rougher the
>>> pavement, the greater the benefit of wider softer tires. Heine, for
>>> example, found ~200W differences on very rough pavement with the wider,
>>> softer tire outperforming the narrower higher pressure tire using a
>>> PowerTap hub as the measuring tool.
>> Is the 200 watt differences a typo?
> Must be a typo. But, at least one measurement tech or engineer
> responsible for testing or reporting estimates of differences in
> coefficients of rolling resistance writes that the differences under
> test greatly underestimate the differences on the road.
> Here are some published estimates of losses for a number of tires on
> the standard smooth drum, for two loaded tires at 30k/h, about 18.5
> mph.
http://www.rouesartisanales.over-blog.com/article-1503651-6.html
> The difference between best and worst clincher pair of standard
> 22-25mm road racing tires was about 20 watts of energy loss.
That's why RR tests are done on smooth steel drums, to avoid the
vagaries of pavement texture and its height and density, that would be
different for every test as the artificial pavement wears. RR test
indicate what the tire tread, casing, and inner tube (if there) absorb
from form change in the load affected zone.
For tires with a tread pattern, tread squirm is a major factor and
that is why slicks are used wherever possible for both better traction
and lower RR.Just listen to SUV's roar by with their huge knobby
tires. Rubber has large hysteretic losses and is why tires at truck
stops are hot enough to burn your hand. They expend much power making
tread noise but that's what the whole vehicle is about... rumble roar
and lots of big tail pipes. MTB riders, descending on paved roads
make similar noise and often, not realizing how much power that
uses... but it sounds macho!
Jobst Brandt
thirty-six
> Harry Travis wrote:
> >>> There is other data that you should be looking at then, or perhaps which
> >>> you have looked at and rejected for some reason. The rougher the
> >>> pavement, the greater the benefit of wider softer tires. Heine, for
> >>> example, found ~200W differences on very rough pavement with the wider,
> >>> softer tire outperforming the narrower higher pressure tire using a
> >>> PowerTap hub as the measuring tool.
> >> Is the 200 watt differences a typo?
> > Must be a typo. But, at least one measurement tech or engineer
> > responsible for testing or reporting estimates of differences in
> > coefficients of rolling resistance writes that the differences under
> > test greatly underestimate the differences on the road.
> > Here are some published estimates of losses for a number of tires on
> > the standard smooth drum, for two loaded tires at 30k/h, about 18.5
> > mph.
>
> http://www.rouesartisanales.over-blog.com/article-1503651-6.html
>
> > The difference between best and worst clincher pair of standard
> > 22-25mm road racing tires was about 20 watts of energy loss.
>
> That's why RR tests are done on smooth steel drums, to avoid the
> vagaries of pavement texture and its height and density, that would be
> different for every test as the artificial pavement wears.
A smooth roller can only really test the rubber tread. What it does
is show that a tyre with a poor casing pumped up very hard will exibit
a lower rolling resistance with a thin tread. Test rollers may be
dressed with a test surface representing a road. As the simplest
reproducable surface an abrasive cloth or paper from a large
established manufacturer in 40 grit may be used.
>RR test
> indicate what the tire tread, casing, and inner tube (if there) absorb
> from form change in the load affected zone.
A smooth roller will not show up the increased drag from edge
deformation which is particularly prevelant with narrow tyres on rough
surfaces.
>
> For tires with a tread pattern, tread squirm is a major factor and
> that is why slicks are used wherever possible for both better traction
> and lower RR.
False. The point about a racing patterned tread is that it is raised
from the surface of a thin treadand so it runs with less resistance at
lower less shock inducing pressures than a similar smooth tread of
full thickness.
>Just listen to SUV's roar by with their huge knobby
> tires.
Somehow I knew you'd get there.
> Rubber has large hysteretic losses and is why
Patterned treads have lower rolling resistance than smooth treads.
> tires at truck
> stops are hot enough to burn your hand.
I wouldn't be so foolish.
> They expend much power making
> tread noise but that's what the whole vehicle is about... rumble roar
> and lots of big tail pipes.
LOL
Tim McNamara
<d5fb040d-d79d-42a3...@u7g2000vbq.googlegroups.com>,
incredulous <travis...@gmail.com> wrote:
> On May 20, 1:12�pm, carlfo...@comcast.net wrote:
> > On Thu, 20 May 2010 09:45:52 -0500, Tim McNamara
> >
> > <tim...@bitstream.net> wrote:
> > >There is other data that you should be looking at then, or perhaps
> > >which you have looked at and rejected for some reason. �The
> > >rougher the pavement, the greater the benefit of wider softer
> > >tires. �Heine, for example, found ~200W differences on very rough
> > >pavement with the wider, softer tire outperforming the narrower
> > >higher pressure tire using a PowerTap hub as the measuring tool.
> >
> > Dear Tim,
> >
> > Is the 200 watt differences a typo?
>
> Must be a typo.
Not a typo, it was recall which wasn't accurate. I didn't see Carl's
post to respond to it. The testing in question was published in the
Autumn 2009 issue of "Bicycle Quarterly." I'm not going to rewrite the
article for the newsgroup; if you're interested in the details, buy a
copy.
Summary: The tests were done using a Tune Power tap and riding the bike
with different tires at a constant speed of 19 mph out and back on the
same stretch of road. Smooth pavement was just what it says; rough
pavement was riding on the rumble strip.
Smooth pavement:
Worst tire (Bontrager Racelite Hardcase 700 x 27 @ 95 psi) = 232 W
Best tire (Panaracer Pasela 700 x 35 @ 50 psi) = 198 W
Difference of 34 W.
Rough pavement:
Worst tire (Bontrager Racelite Hardcase 700 x 27 @ 95 psi) = 479 W
Best tire (Panaracer Pasela 700 x 35 @ 50 psi) = 313 W
So the difference was 160 W on rough pavement, not the ~ 200 W I
recalled.
> But, at least one measurement tech or engineer responsible for
> testing or reporting estimates of differences in coefficients of
> rolling resistance writes that the differences under test greatly
> underestimate the differences on the road.
The underestimate is probably explained in suspension losses as the bike
bounces over the surface. These losses are probably mainly due to
hysteresis in the rider's body; hysteresis in tissue is also a factor in
losses in normal physical activity, hence why compression clothing shows
a gain in performance.
Heine's testing also compared forks using the same wheels on the same
bike.
Smooth pavement:
Worst fork: Trek unicrown with large diameter legs: 237 W
Best fork: RockShox Ruby: 203 W
Rough pavement:
Worst fork: Trek hybrid unicrown with large diameter legs: 459 W
Best fork: (tie) Rock Shox Ruby @ 428 W and Alex Singer thin steel @
426 W
Interesting that the suspension fork provided about the same reduction
in energy cost to maintain a constant speed, ~ 30W, on both smooth and
rough pavement. The differences between worst and best tires was much
greater between smooth and rough pavement. Stiction in the suspension
fork mechanism might explain this.
Jay Beattie
I've owned both those tires, and with the Pasela, you have to figure
in time for fixing flats -- like on Thursday when I flatted my Pasela
in the rain (well, it's raining every day, so any flat is in the
rain). The Hardcase is like riding on wooden wagon wheels. Neither
is as fast as the 23mm Michelin Pro Race on the same road. This is
based on sensitive instrumentation (me) over the identical piece of
road multiple times. -- Jay Beattie.
thirty-six
ROTFL - So I should wear a corset and hose to stop my flabby bits
bouncing around?
>
> Heine's testing also compared forks using the same wheels on the same
> bike.
>
> Smooth pavement:
> Worst fork: Trek unicrown with large diameter legs: 237 W
> Best fork: RockShox Ruby: 203 W
>
> Rough pavement:
> Worst fork: Trek hybrid unicrown with large diameter legs: 459 W
> Best fork: (tie) Rock Shox Ruby @ 428 W and Alex Singer thin steel @
> 426 W
>
> Interesting that the suspension fork provided about the same reduction
> in energy cost to maintain a constant speed, ~ 30W, on both smooth and
> rough pavement. The differences between worst and best tires was much
> greater between smooth and rough pavement. Stiction in the suspension
> fork mechanism might explain this.
Please clarify, are you saying that a suspension fork reduced the
required input power to maintain a given speed (which was?) on a
smooth road?
Tim McNamara
<54fcbd7d-380b-42a3...@32g2000prq.googlegroups.com>,
Jay Beattie <jbea...@lindsayhart.com> wrote:
I've had some flats with the Paselas but it doesn't seem to be any more
frequent than with the other tires I have used (mainly Continental GPs
and Ultra sport 2000s, Michelin Super Comp HDs, Ritchey Tom Slicks and
Primos). The Panacers seem more flat resistant than the aforementioned
Ritcheys and Primos, but they are not a puncture-resistant tire. The
Pasela 700 x 28s are pretty fast tires, noticeably so compared to the
700 x 25 version. I've never tried the Bontragers.
The Pro Race 2's were rated highly in a previous tire test by Bicycle
Quarterly, the slightly larger version (25 mm?) outperforming the
smaller version by a tiny difference.
Jay Beattie
>
> - Show quoted text -
I had some of the 25mm Pro Race (first generation) and they were like
28mm. I wasn't paying attention when I put them on my Cannondale and
did not notice that they were rubbing on the underside of my rear
brake caliper -- until I had been dropped off by my wife to ride home
from out in the countryside (long story). I ended up taking off my
rear brake and flipping it to the inside of the bridge to get a little
more clearance. That was probably the biggest difference between
nominal and actual tire size that I had ever seen. Those tires lived
out the rest of their lives on my commuter.--- Jay Beattie.
thirty-six
Was this on a particularly narrow rim?
carl...@comcast.net
<tim...@bitstream.net> wrote:
Dear Tim,
It might be more helpful to describe it as a 160 watt difference on a
rumble strip, not rough pavement.
Cheers,
Carl Fogel
Jay Beattie
<snip>
Velocity Aerohead OC. -- Jay Beattie.
Tim McNamara
Tim McNamara <tim...@bitstream.net> wrote:
> I've had some flats with the Paselas but it doesn't seem to be any
> more frequent than with the other tires I have used (mainly
> Continental GPs and Ultra sport 2000s, Michelin Super Comp HDs,
> Ritchey Tom Slicks and Primos). The Panacers seem more flat
> resistant than the aforementioned Ritcheys and Primos, but they are
> not a puncture-resistant tire.
And I went out and had one today!
thirty-six
So less than 17mm int. rim? 14mm?
Fred on a stick
> I have only read Jan's seconday reports of the experimental design.
The BQ tests aren't described in sufficient detail to know the level of
precision in those estimates..
> Maybe engineers in this
> group could propose an inexpensive alternative to the roll-down tests.
Yeah, right. You'll have better luck asking on rec.bicycles.racing than
here.
Jobst Brandt
>> I have only read Jan's secondary reports of the experimental design.
> The BQ tests aren't described in sufficient detail to know the level
> of precision in those estimates..
>> Maybe engineers in this group could propose an inexpensive
>> alternative to the roll-down tests.
> Yeah, right. You'll have better luck asking on rec.bicycles.racing
> than here.
Roll-down tests are strongly affected by air drag because the bicycle
is moving, therefore, making strain gauge measurement on rotational
energy is a far better measure of the tire losses.
Jobst Brandt
Fred on a stick
Exactly why you'd have btter luck asking on rec.bicycles.racing. There's
more experience with measurements of that type over there than here.
thirty-six
wrote:
> Exactly why you'd have btter luck asking on rec.bicycles.racing. There's
> more experience with measurements of that type over there than here.
The first tests for pneumatic tyre were made by RW Thomson and the
method employed was to measure the draw bar tension of the loaded
carriage over the cobbled road at a steady rate. A single trailing
wheel could be loaded and the test performed in the same manner. It
can be done indoors so would not be affected at all by windage.
Jay Beattie
> In article <timmcn-6781F4.16193029052...@news-1.mpls.iphouse.net>,
On a related note, I was riding today and stopped to adjust my saddle
and noticed my rear ProRace was down to the cords -- I guess it pays
to look at your tires now and then. The good part about PDX is that
you are never far from a bike shop -- a Performance in this case, so I
went and got their house-version Vredestein (Fortezza) race/training
tire for $24 and went for a ride. I did not notice a huge difference
except color -- the tire is blue. In the past, I have been
disappointed by the Performance Vredestein's wet traction, but it was
reasonably dry today. No flats even though part of the ride was a
climb on a rocky fire road. -- Jay Beattie.
Fred on a stick
"thirty-six" <thirt...@live.co.uk> wrote in message
news:9ca217ec-53c6-473a...@e6g2000vbm.googlegroups.com...
Y'all are making my point for me: if Harry had wanted to know how to measure
differences in rolling drag with accuracy and precision, rbt isn't the place
to ask.
thirty-six
> On May 18, 10:21 pm, Michael Press <rub...@pacbell.net> wrote:
>
>
>
> > In article <hsv4un$96...@reader1.panix.com>,> > > :In article <timmcn-A1029F.23532817052...@news-2.mpls.iphouse.net>,
> > > : Tim McNamara <tim...@bitstream.net> wrote:
>
> > > :> In article <hsrc55$rk...@news.eternal-september.org>,
> > > :> many people's surprise, those tires can also be faster on smooth
> > > :> pavement. Skinny high pressure tires are not necessarily faster.
> > > :> There's a lot of data about this but many people refuse to accept it.
>
> > > :Most of the data is from road racers who ride narrow,
> > > :high pressure tires in all conditions. Until racer
> > > :preference is explained, lower energy dissipation of
> > > :wide, low pressure tires on roads is not proven.
>
> > > a lot more than bike tire people, say. On a bike, though, air
> > > friction is going to overwheml the difference at some point. I don't
> > > know where the cross over point is, but I'd quess it's around 20mph,
> > > which is where it is for so many things.
>
> > incline on pavement outside in the wind. There are
> > temperature differences, humidity differences, and wind
> > differences the tester has to account for; but he did
> > not. He did not have a control bicycle that he ran
> > every time and correlated the times with temperature,
> > humidity, and wind speed so as to be able to remove
> > those effects from the tires of interest. He did not
> > run each tire at a variety of inflation pressures. I
> > conclude that the experiment did not do enough to
> > resolve differences among the tire; and drawing
> > conclusions from the report is an act of faith.
>
> > At this point the choice of racers is the best data we have.
>
> > I want to know how much power is dissipated from the
> > effects of rough pavement on various tires transmitted
> > to the rider; more than those who hang their hats on the
> > bicycle magazine bicycle roll down tests.
>
> > --
> > Michael Press
>
> I have only read Jan's seconday reports of the experimental design. I
> wonder if he doesn't depend on a too-literal model of the riding
> situation, what with real rider and bicycle.
Yes.
>Maybe engineers in this
> group could propose an inexpensive alternative to the roll-down tests.
>
> For example, why use a bicycle at all?
To tow a trailer, onto which the test wheel is mounted, at cycling
speeds over real variable road surfaces.
>
> Why not a simple remote-controllable two or three-wheel cart driven by
> a small electric motor?
Towing bicycles and riders already available.
> Use one small motor to bring it up to a
> specified speed, and then another small motor sustain the speed over a
> course, measuring the power consumed.
Usually using the same human motor works well.
Measure draw bar tension
> Run the cart in both directions
Dicey using same surface on public roads.
> on a straight pretty-level road; or have it run in a repeatable circle
> on a vacant parking lot. With pairs or triplets of tires of the same
> type, between-sample error-variance contribution is reduced, and tire-
> rolling resistance contributions to power-sucking will go further in
> overwhelming air-resistance effects.
You wouldn't then want to be going in circles because of steering
scrub creating a greater drag than the intended majority measurement.
>
> Replicate over different tires, surfaces, tire pressures, cart-weights
> and speeds, as desired.
To show up anomalies in test procedure and trends in tyre design as
they perform across the different surfaces..
>
> And except for the desired human company and help in changing tires,
> this setup can be run by one person.
With a wind direction and speed sensors on the trailer, there is no
reason why the tests cannot be performed over different days.
>
> What's wrong with this design? If not much, how much might it cost to
> to construct and instrument the several components of the cart
> (without the donated CF wheels)?
It's more complex than a trailer behind a bike and requires skills in
learning to control and regulate. It's more costly. less likely to
be reproducible.
thirty-six
wrote:
> "thirty-six" <thirty-...@live.co.uk> wrote in message
I think your missing the point. Four figure accuracy is not required,
quality of test procedure IS.
Fred on a stick
"thirty-six" <thirt...@live.co.uk> wrote in message
news:c0a56020-21c3-4c7b...@m4g2000vbl.googlegroups.com...
Exactly. Harry asked his question 12 days ago and got no replies. I wandered
in yesterday and immediately saw the issue: if he wants to talk to people
who have actually estimated drag forces on smooth and bumpy roads, rbt ain't
the place. Instead he gets suggestions to measure draw bar tension.
thirty-six
wrote:
> "thirty-six" <thirty-...@live.co.uk> wrote in message
Yes , measuring draw bar tension is measuring the drag of a wheel,
exactly. This is not about estimation, but a reliable method of
MEASUREMENT. I meant to reply earlier but was sidetracked and hoped
ther might be someone with a modicum of sense an d memory to chirp
in.
Tim McNamara
Are you deliberately trolling? We have and have had participants in
this newsgroup who have done bicycle tire designing and testing. The
odds are that they have as much or more expertise in this topic than
most in other newsgroups (except of course where those same participants
overlap).
Tim McNamara
"Fred on a stick" <anonymou...@address.invalid> wrote:
Yeah, well, thirty-six a.k.a. Trevor is a bit of an idiot. Ignore him,
I do.
Fred on a stick
"Tim McNamara" <tim...@bitstream.net> wrote in message
news:timmcn-72B3C9....@news-2.mpls.iphouse.net...
I think the operative word in your first sentence is "had." Harry asked his
question 12 days ago. How many replies did he receive from rbt's current
participants? Cuz maybe my news feed didn't capture the replies from these
experts. If so, then I retract my claim. If not, the evidence is that he
would've had better luck elsewhere. For god's sake, man, he would've had
better luck getting his question answered on r.b.racing, which should be a
wake up and smell the coffee call since that newsgroup is filled with
dumbasses.
thirty-six
> In article <hu0hom$r1...@news.eternal-september.org>,
> "Fred on a stick" <anonymous.cow...@address.invalid> wrote:
>
>
>
> > "thirty-six" <thirty-...@live.co.uk> wrote in message
> >news:c0a56020-21c3-4c7b...@m4g2000vbl.googlegroups.com.
> > ..
> > > On 31 May, 13:39, "Fred on a stick"
> > > <anonymous.cow...@address.invalid> wrote:
>
> > >> Y'all are making my point for me: if Harry had wanted to know how
> > >> to measure differences in rolling drag with accuracy and
> > >> precision, rbt isn't the place to ask.
>
> > > I think your missing the point. Four figure accuracy is not
> > > required, quality of test procedure IS.
>
> > Exactly. Harry asked his question 12 days ago and got no replies. I
> > wandered in yesterday and immediately saw the issue: if he wants to
> > talk to people who have actually estimated drag forces on smooth and
> > bumpy roads, rbt ain't the place. Instead he gets suggestions to
> > measure draw bar tension.
>
> Yeah, well, thirty-six a.k.a. Trevor is a bit of an idiot. Ignore him,
> I do.
Dim is the 100% genuine article.
Tim McNamara
"Fred on a stick" <anonymou...@address.invalid> wrote:
> "Tim McNamara" <tim...@bitstream.net> wrote in message
> news:timmcn-72B3C9....@news-2.mpls.iphouse.net...
> > In article <hu0all$s93$1...@news.eternal-september.org>, "Fred on a
> > stick" <anonymou...@address.invalid> wrote:
> >
> >> "thirty-six" <thirt...@live.co.uk> wrote in message
> >> news:9ca217ec-53c6-473a...@e6g2000vbm.googlegroups.c
> >> om. ..
> >> > On 30 May, 22:56, "Fred on a stick"
> >> > <anonymous.cow...@address.invalid> wrote:
> >> >
> >> >> Exactly why you'd have btter luck asking on
> >> >> rec.bicycles.racing. There's more experience with measurements
> >> >> of that type over there than here.
> >> >
> >> > The first tests for pneumatic tyre were made by RW Thomson and
> >> > the method employed was to measure the draw bar tension of the
> >> > loaded carriage over the cobbled road at a steady rate. A
> >> > single trailing wheel could be loaded and the test performed in
> >> > the same manner. It can be done indoors so would not be
> >> > affected at all by windage.
> >>
> >> Y'all are making my point for me: if Harry had wanted to know how
> >> to measure differences in rolling drag with accuracy and
> >> precision, rbt isn't the place to ask.
> >
> > Are you deliberately trolling? We have and have had participants
> > in this newsgroup who have done bicycle tire designing and testing.
> > The odds are that they have as much or more expertise in this
> > topic than most in other newsgroups (except of course where those
> > same participants overlap).
>
> I think the operative word in your first sentence is "had." Harry
> asked his question 12 days ago. How many replies did he receive from
> rbt's current participants?
I've seen quite a few responses and have posted several myself. Looking
at the thread in Google Groups, I see 58 responses being the count as of
a couple of minutes ago. Three or four of those responses are from
mechanical engineers with experience in the field.
> Cuz maybe my news feed didn't capture the replies from these experts.
> If so, then I retract my claim. If not, the evidence is that he
> would've had better luck elsewhere. For god's sake, man, he would've
> had better luck getting his question answered on r.b.racing, which
> should be a wake up and smell the coffee call since that newsgroup is
> filled with dumbasses.
Or at least so they call each other. I know at least one of those guys
ITRW and he is far being being a dumbass (having been a computer whiz
for Cray, Silicon Graphics, etc., his brain seems to be fine). I see
enough "dumbass" salutations in the thread that it appears at least some
of the r.b.r. crew is participating in the thread.
Fred on a stick
"Tim McNamara" <tim...@bitstream.net> wrote in message
news:timmcn-8DB725....@news-2.mpls.iphouse.net...
> "Fred on a stick" <anonymou...@address.invalid> wrote:
>> I think the operative word in your first sentence is "had." Harry
>> asked his question 12 days ago. How many replies did he receive from
>> rbt's current participants?
>
> I've seen quite a few responses and have posted several myself. Looking
> at the thread in Google Groups, I see 58 responses being the count as of
> a couple of minutes ago. Three or four of those responses are from
> mechanical engineers with experience in the field.
Ah, thanks for that. I just looked at Google Groups and I can verify that
after your post there are now 59 total responses -- none of which responded
to Harry's question of May 18th. Your three or four mechanical engineers
with experience in the field? Pretty quiet.
Tim McNamara
"Fred on a stick" <anonymou...@address.invalid> wrote:
> "Tim McNamara" <tim...@bitstream.net> wrote in message
> news:timmcn-8DB725....@news-2.mpls.iphouse.net...
> > "Fred on a stick" <anonymou...@address.invalid> wrote:
>
> >> I think the operative word in your first sentence is "had." Harry
> >> asked his question 12 days ago. How many replies did he receive
> >> from rbt's current participants?
> >
> > I've seen quite a few responses and have posted several myself.
> > Looking at the thread in Google Groups, I see 58 responses being
> > the count as of a couple of minutes ago. Three or four of those
> > responses are from mechanical engineers with experience in the
> > field.
>
> Ah, thanks for that. I just looked at Google Groups and I can verify
> that after your post there are now 59 total responses -- none of
> which responded to Harry's question of May 18th. Your three or four
> mechanical engineers with experience in the field? Pretty quiet.
The thread was started by Mark Cleary on 5/17/10 and my attention has
been on answering his question, which was about riding on smooth versus
rough pavement and the relative energy costs.
You appear to be referring to this question of 5/18/10 by Harry. Please
clarify *which* question are you stating hasn't been answered? There
are four explicit questions in his post, after all, and at least one
implicit question. It's difficult to know which one you are wittering
on about.
> I have only read Jan's seconday reports of the experimental design. I
> wonder if he doesn't depend on a too-literal model of the riding
> situation, what with real rider and bicycle. Maybe engineers in this
> group could propose an inexpensive alternative to the roll-down tests.
>
> For example, why use a bicycle at all?
>
> Why not a simple remote-controllable two or three-wheel cart driven by
> a small electric motor? Use one small motor to bring it up to a
> specified speed, and then another small motor sustain the speed over a
> course, measuring the power consumed. Run the cart in both directions
> on a straight pretty-level road; or have it run in a repeatable circle
> on a vacant parking lot. With pairs or triplets of tires of the same
> type, between-sample error-variance contribution is reduced, and tire-
> rolling resistance contributions to power-sucking will go further in
> overwhelming air-resistance effects.
>
> Replicate over different tires, surfaces, tire pressures, cart-weights
> and speeds, as desired.
>
> And except for the desired human company and help in changing tires,
> this setup can be run by one person.
>
> What's wrong with this design? If not much, how much might it cost to
> to construct and instrument the several components of the cart
> (without the donated CF wheels)?
As for critiques of Jan Heine's experimental design, I would refer the
reader to his Web site which includes an e-mail address. I know from
experience that Jan will discuss critiques sent to him, as I sent him
several about his roll-down tests for rolling resistance. None of us
here can defend Jan's experimental design in his absence and he does
not, as far as I know, generally read this newsgroup (although he did
participate in the discussion about his roll-down tests).
To answer Harry's implicit question: an inexpensive testing device
depends only on your ingenuity, mechanical aptitude, and fundamentally
understanding how rolling resistance works.
To answer Harry's first explicit question: there is no reason nor
necessity to use a bicycle to determine rolling resistance. Tire
manufacturers such as Continental and others do not use a bicycle to
test rolling resistance. This link has already been referenced and
shows a partial photo of a rolling resistance rig. By the way, this
question was already answered by Jobst Brandt when he identified the
main drawback to using a bicycle and a roll-down test.
http://www.rouesartisanales.com/article-1503651.html
To answer Harry's second explicit question: the best way to do an
experiment is generally the simplest. This is not it.
To answer Harry's third explicit question: your experimental design is
too complicated and introduces so many degrees of freedom that
controlling for confounds will be difficult if not impossible, rendering
your measurements of questionable validity.
To answer Harry's fourth explicit question: I have no way to estimate
what it would cost Harry to build such a device and try to employ it.
Local price variations for materials, his ability to do competent design
work himself, his ability to do fabrication, etc., would all factor in.
This question is functionally unanswerable.
In conclusion, "Fred on a stick," I would like to offer my sincere
apologies that the customer service at rec.bicycles.tech has not met
your expectations as proxy for Harry and has not provided you with the
free detailed analysis for which you hoped. You may apply for a full
refund, of course. Try Mr. Barnard; room 12.
Cheerio!
Fred on a stick
> You appear to be referring to this question of 5/18/10 by Harry.
Really? You just figured that out? Was the clue that I specified "Harry" and
"May 18"? Man, you're perceptive.
> Please clarify *which* question are you stating hasn't been answered?
*Which* of his questions hadn't been answered? Are you serious? This
perceptiveness thing really doesn't seem like your strong suit. Okay: all of
them. Maybe you'll understand it better this way: if all of his questions
hadn't been answered, then none of his questions were answered. Since you're
a little unclear on this concept, let me explain: he got no replies. "No
replies" as in, zero replies. None. Nada. Zilch. Bupkis. The number of
replies was one less than the least positive integer. The log of 1. If it
were a temperature, it would be -273 degrees celsius because it was
absolutely zero. While waiting for his replies, he met a man with seven
wives. Each wife had seven sacks. Each sack had seven cats. How many
questions did he ask that were answered? None. You know this arithmetic
thing? You really don't seem to be all that good at it. He would've had
better luck getting his question answered elsewhere than by your mechanical
engineering experts. Thanks for proving my point.
Tim McNamara
"Fred on a stick" <anonymou...@address.invalid> wrote:
> "Tim McNamara" <tim...@bitstream.net> wrote in message
> news:timmcn-96F419....@news-1.mpls.iphouse.net...
>
> > You appear to be referring to this question of 5/18/10 by Harry.
>
> Really? You just figured that out? Was the clue that I specified
> "Harry" and "May 18"? Man, you're perceptive.
Since I hadn't seen Harry's post, it was helpful for you to be more
specific. Interestingly, Harry doesn't seem to have much cared that he
didn't "get an answer" whereas you have a bug up your ass about it.
> > Please clarify *which* question are you stating hasn't been
> > answered?
>
> *Which* of his questions hadn't been answered? Are you serious? This
> perceptiveness thing really doesn't seem like your strong suit. Okay:
> all of them. Maybe you'll understand it better this way: if all of
> his questions hadn't been answered, then none of his questions were
> answered. Since you're a little unclear on this concept, let me
> explain: he got no replies. "No replies" as in, zero replies. None.
> Nada. Zilch. Bupkis. The number of replies was one less than the
> least positive integer. The log of 1. If it were a temperature, it
> would be -273 degrees celsius because it was absolutely zero.
That's a lie, as I pointed out. Honesty is apparently not your strong
suit.
> While waiting for his replies, he met a man with seven wives. Each
> wife had seven sacks. Each sack had seven cats. How many questions
> did he ask that were answered? None. You know this arithmetic thing?
> You really don't seem to be all that good at it. He would've had
> better luck getting his question answered elsewhere than by your
> mechanical engineering experts. Thanks for proving my point.
And thanks for proving that you're a liar and an asshole. Best of luck
with the technical experts in wreck.bikes.racing, dumbass. LOL!
Fred on a stick
"Tim McNamara" <tim...@bitstream.net> wrote in message
news:timmcn-63E8C1....@news-2.mpls.iphouse.net...
> That's a lie, as I pointed out. Honesty is apparently not your strong
> suit.
[...]
> And thanks for proving that you're a liar and an asshole. Best of luck
> with the technical experts in wreck.bikes.racing, dumbass. LOL!
Dude, I don't know if you have kids or grandkids but years from now one of
them is going to google you up and see that you're not only wrong but you're
nasty about it. Matter of fact, I don't know if your mom is still around but
judging from your level of immaturity maybe you're quite young so she can
google you up, too. Is this the kind of son she's going to be proud to have
raised? Meanwhile, back in the present, you're clearly one of the reasons
why rbt is moribund and knowledgeable discussions of technical issues have
moved elsewhere. Here's the thing: I only just dropped in. I get to drop
back out. You're obviously a little too invested in this place.
Tim McNamara
"Fred on a stick" <anonymou...@address.invalid> wrote:
I'm not the one telling lies, "Fred." Nor am I the one who has to keep
upping the ante. You want someone's behavior to criticize, try looking
in the mirror first.
All of "Harry's" answerable questions were answered. 'Nuff said.
Cheers!