Bikes: 700/23 vs 700/25 tires?

[Michael Press]

In article
<d98421f2-dc60-40f6-913a-0bd6d36accd0@z6g2000pre.************.com>,
Chalo <chalo.colina@**********> wrote:

> Michael Press wrote:
> >
> > Chalo wrote:
> > >
> > > I find my own personal sweet spot for speed and tire reliability in
> > > the 35-40mm range of tire width. *I don't assume this would be the
> > > same for other riders. *However, I have spent a lot of time with the
> > > urban cycling community in both Seattle and Austin, and I have seen
> > > again and again young messengers and self-styled sport riders come to
> > > the realization that 28mm tires are no slower than narrower ones, but
> > > are way better at getting you there with air still in the tires and
> > > wheels intact. *I don't think this is mere coincidence. *I do think
> > > that they often stop at 28mm because so many of their bikes can't
> > > accept a fatter tire than that.
> >
> > The real change over is at 25 mm. Above that casings
> > _must_ be made thicker. I ride 28 and 25. The 28 with
> > the thin flexible casing is very good, particularly for
> > utility riding. The 25 with the very good casing is better.
>
> I believe that a good 25mm tire has lower rolling resistance than a
> thicker 28mm tire. But there is a trade between raw natural RR and
> effective RR, which is to say tire losses plus the energy transmitted
> to the rider as shock that is subtracted from the bike's kinetic
> energy. At a certain surface roughness and speed, 28mm becomes
> faster, even if it has a touch more natural RR on a smooth surface.
> Turn up the surface roughness even more, and an even fatter tire
> becomes faster. Hence MTBs.
>
> People who drive their bikes to the smoothest roads they can find, so
> they can ride their pretend racing bikes and scatter goo packets and
> CO2 cartridges all over the place, are generally able to use smaller
> tires than folks who ride on the streets that run between where they
> are and where they want to go.

I am speaking only of utility cycling. I would put 25's
on my utility bike, but it has 630 rims. The pavement
varies here, with plenty of rough, though likely not
as much as other places. The difference in rolling
resistance between my bike and the wide tire bikes
is unmistakeable. I can _see_ how much effort people
put into pedaling their bikes, and the wide tire
people are working harder than me. I am quite lazy
on a bicycle; that is why I use high pressure slicks.
When I chose to put a bit of oomph into the pedals
I am flying. When a wide tire bike flies past me
the sound of the tread on the pavement tells the
tale: enormous loses in tire flex.

Whirr, whirr, whirr, whirr, whirr, whirr, whirr, whirr, whirr, ...

--
Michael Press

[Michael Press]

In article
<303d08f0-df99-4835-b997-dbf2077224e5@g3g2000pre.************.com>,
"dustoyevsky@mac.com" <dustoyevsky@mac.com> wrote:

> On Feb 2, 8:02*pm, carlfo...@************ wrote:
>
> > After all, what else could explain Armstrong's margin over Ullrich up
> > the Alp d'Huez?
>
> Weight reduction I think it's agreed was key there.
>
> Measured in bratwurst per fortnight.

Bratwurst is measured by the link.
So that is ~ 0.0000006 km/hour.
If that sort of advantage could be accrued
a million times we are talking first place.

--
Michael Press

[Nick L Plate]

On 3 Feb, 19:03, carlfo...@************ wrote:

> On Mon, 2 Feb 2009 23:28:49 -0800 (PST), Nick L Plate
> <tj-j...@******************> wrote:

> >I believe the best that can be done is a rolldown test upon the
> >course. *A relatively shallow downgrade is what is called for. *The


> Let us know when such tests are performed.

Might seem an impractable amount of time, but once tyre, pressure and
road surface has been matched, you have the results for future
reference. It is individual to the rider, and is likely worthwhile
for someone racing every week, with a probable 3 year plus racing
career. For the dedicated, it is time better spent than worrying
about weight and aerodynamics with its associated costs and
reliability which goes with the terriotry.

[Frank Krygowski]

On Feb 3, 9:33*pm, Michael Press <rub...@pacbell.net> wrote:
> I
>
> 5) A racer who dismisses a potential advantage as
> negligible has already lost race.

Then, as Carl has suggested, every rider that doesn't clip his
fingernails and toenails, shave all body hair, tape his ears back, and
use enemas and catheters has no chance! And those who eschew drilled
AX (aerodynamic) components are even worse!

Is that what you meant?

Or is there such a thing as "negligible" after all?

- Frank Krygowski

[Michael Press]

In article
<2eed41b1-76c5-4d23-ab9a-0a43f2f707e8@a12g2000yqm.************.com>,
Frank Krygowski <frkrygow@**********> wrote:

> On Feb 3, 9:33*pm, Michael Press <rub...@pacbell.net> wrote:
> > I
> >
> > 5) A racer who dismisses a potential advantage as
> > negligible has already lost race.
>
> Then, as Carl has suggested, every rider that doesn't clip his
> fingernails and toenails, shave all body hair, tape his ears back, and
> use enemas and catheters has no chance! And those who eschew drilled
> AX (aerodynamic) components are even worse!
>
> Is that what you meant?
>
> Or is there such a thing as "negligible" after all?

I am not defining negligible, am I?
I do not presume to assert what is negligible.
Read what I wrote. How do I use `negligible'?

--
Michael Press

[Nick L Plate]

On 4 Feb, 07:14, carlfo...@************ wrote:
> On Tue, 3 Feb 2009 22:48:16 -0800 (PST), Nick L Plate
>
>
>
> <tj-j...@******************> wrote:
> >On 4 Feb, 04:57, Michael Press <rub...@pacbell.net> wrote:
>
> >> Roll down tests on thin wall slick tires
> >> prove that they have considerable less
> >> rolling resistance than other tires.
>
> >Whoose tests? *Can you trust them?
> >Which piece of road?
> >Was the same wheel used?
> >Is the wheel used optimal for the tyre?
> >Were the wheel's stiffness, at the test load, the same for all tyres?
> >Where optimal pressures found for each tyre for given loads?
> >What was the actual force necessary to maintain 30mph on the level?
> >How about 38mph? *22mph?
>
> >Practical experience with an early 20-21mm HP high performance tyre vs
> >one of slightly inferior construction at 23mm showed me that the wider
> >tyre was more appropriate in a race situation. *Bi-weekly jaunts on
> >the chain gang permitted me to experiment. *Taking a regular timed
> >turn at the front, I was unable to maintain effort past a certain
> >distance, and would usually follow alone rather tag onto the end.
> >Usually the Tuesday run was 38mph+, Thursdays a little slower.
> >Changing to the wider tyre, I could keep up the effort required to
> >maintain 38mph for longer, usally completing the run after full
> >contribution. *I was also less stressed following the workout. *A
> >return to the higher grade narrow tyre after 23 was ripped was also a
> >return to not completing the chaingang. *I t was not necassary for me
> >to otherwise test the tyres because it was clear that a 23mm tyre or
> >larger on the back permitted me to ride longer at high speeds.
> >Reference to other tests would unlikely help me because they do not
> >include me.
>
> >The roads taken were of a good surface for cycling. *Not obviously
> >rough. *Well not at 20mph.
>
> Dear Trevor,
>
> Was this before or after your 70+ mph runs in the Welsh countryside?
>
> Cheers,
>
> Carl Fogel

well done.

218 rpm on a 700 Hutchinson AS 22 and 52x13 is in excess of 68mph
118 rpm is in excess of 38mph
I thought it possible to exceed 70mph, such as with a 54t ring, I did
not exceed 70mph pedaling a solo bicycle, that would infringe the laws
of the land. I also had not developed the co-ordination which later
permitted me a cadence of 230rpm.

[Carl Sundquist]

carlfogel@************ wrote:

> Dear Trevor,
>
> A new record for your posts--230 RPM!
>
> Did it help reduce rolling resistance when both your tires left the
> ground like a kangaroo when you pedaled hard?
>
> Cheers,
>
> Carl Fogel

Why would the tires leave the ground?

[Frank Krygowski]

On Feb 4, 6:35*am, John Forrest Tomlinson <usenetrem...@jt10000.com>
wrote:
> On Tue, 3 Feb 2009 21:17:37 -0800 (PST), Frank Krygowski
>
> <frkry...@**********> wrote:
> >Then, as Carl has suggested, every rider that doesn't clip his
> >fingernails and toenails, shave all body hair, tape his ears back, and
> >use enemas and catheters has no chance!
>
> I know you're trying to mix humour with an argument, but this joke
> reflects a sad luddite/envy or luddite/contempt on Carl's part, and
> perhaps yours.
>
> If people were going around trying to force you to stuff to speed up,
> I could feel some sympathy. *But the fervor with which Carl and others
> like to denounce other people trying to get faster is reactionary and
> telling about themselves. *

John, if someone wants to try to get faster, that's fine. I'm no
longer into riding as fast as I can - I'm too old, and I no longer
have the willingness to hurt that much. But I can recall enjoying
covering a section of road fifteen seconds faster than my usual time.
I can recall enjoying finishing a time trial so precisely exhausted
that I didn't dare try to stand for five minutes. I can recall doing
things to lighten my bikes, or make them more aerodynamic, and I still
do some of that.

I think my posts can be summarized by a few points:

Not every "go fast" idea actually increases speed. You can't believe
all the hype, nor all the fashion.

There are benefits and detriments to be balanced even for ideas that
do add speed. Smart people look at both sides of that scale, and
apply first the strategies that give maximum benefit for minimum
detriment. It may not be what's fashionable.

If something increases speed, but by so small a margin that it is
practically undetectable, it should be considered negligible. Its
detriments will probably overbalance the minuscule benefit.

And if road races are ever won because of (say) a 0.05% reduction in
weight or aero drag, it happens less than one time out of 100,000.

What I read in response to those ideas is (paraphrasing) "No
improvement is negligible," and "You don't understand racing." But
those arguments don't explain the typical racer's unshaven body hair
or protruding ears. They don't explain why handlebars still have
flat, unstreamlined ends or why "drillium" went out of fashion.

The other point that I've made is this: For a non-racer or a non-
competitive racer, none of the little "go fast" changes are likely to
transform the ride.

Still, some people love tweaking their bikes. Other people love
working crossword puzzles, and both are fine hobbies. But when
someone comes here and asks about whether tweaking the bike makes a
noticeable difference, we should honestly point out that most of it is
as productive as working a crossword puzzle.

- Frank Krygowski

[Nick L Plate]

On Feb 4, 12:16*pm, Carl Sundquist <carl...@cox.net> wrote:
> carlfo...@************ wrote:
> > Dear Trevor,
>
> > A new record for your posts--230 RPM!
>
> > Did it help reduce rolling resistance when both your tires left the
> > ground like a kangaroo when you pedaled hard?
>
> > Cheers,
>
> > Carl Fogel
>
> Why would the tires leave the ground?

It is a reference to when I buckled a front wheel when sprinting
following consumption of a few beers. It has nothing to do with a
training ride when I attained 230rpm some ten years later.

[Frank Krygowski]

On Feb 4, 7:28*pm, John Forrest Tomlinson <usenetrem...@jt10000.com>
wrote:
> On Wed, 4 Feb 2009 09:18:59 -0800 (PST), Frank Krygowski
>
> <frkry...@**********> wrote:
> >If something increases speed, but by so small a margin that it is
> >practically undetectable, it should be considered negligible.
> > Its
> >detriments will probably overbalance the minuscule benefit.
>
> It's certainly possible that detriments can be larger, but to simply
> assume that is usually the case is just *plain silly. So I have to ask
> again, do you use this sort of rationale in other aspects of life? *If
> you can't measure a change, but it possibly might be a good idea, you
> refuse to do it? * It could have detriments that overbalance the
> minimal benefit?
>
> I have to laugh.

?

We may be further apart in our thinking than I realized.

If I have no way of telling that something will produce a worthwhile
benefit, I certainly don't go out of my way to do it. For example,
I'm not likely to move my money out of one account and into another
unless the new account pays more interest than the old. Would you
instead say "It might possibly pay more, so I'm just going to try it
and see"?

In general, one doesn't have to precisely calculate the expected
benefit. If you know enough of the physics or economics, you can
often judge benefits accurately enough to make a good decision. If
you don't know, you're likely to waste money, time, or other
resources.

Here's an example: I know enough about heat flow, furnace efficiency,
our local climate, etc. to reliably judge that it's worthwhile
weatherstripping doors and windows. And when we recently did some
remodeling, I knew that increasing the insulation in the new area was
a wise move. Although I've done complete heating load calculations in
the past, I felt no need to repeat them. I also had enough data to
easily justify the increased cost of a high efficiency furnace.

But I also know enough to stay away from the heavily advertised (in
our area, at least) "Amish" electric heaters. Despite the expensive
full page ads with the charming photos of (apparently) Amish couples
building heaters and hauling them to the store in horse-drawn
carriages, I know these things are exactly as efficient as any other
electric heater, but more expensive.

I think lots of folks must think those heaters are "possibly a good
idea" and buying them. I hope for your sake you're not one of them!

- Frank Krygowski