Latex on tubular base tape

Sandy wrote:


Please don't take offense, Peter. I am here to back you up, really.
If anyone were to scan the declarations made by the teams, that person would
find that 17 of the 22 teams use tubulars for all stages, and two of the
remaining five use them for time trials. This information comes from the
teams, and is usually collected by the media. It happens that the list I
used was in Le Cycle, where all components of all bikes were listed in the
Tour special insert.

Briefly, Peter, you are totally on target and right. Your experience is
broad based, and much more representative of reality than misinformation
offered by others. I have sent Mr Brandt the excepts of the tire testing
which seems to cut his blather down to size. I sent him a subscription form
for one magazine I read, and I think folks in other countries could probably
send others. Even in English, from England, where they do good reporting.
But he won't buy it, preferring to bark and grumble and scoff.

For my part, I gave up tubulars only because I have ten glue magnets on my
hands, and it really is a better clincher world today than 20 years ago.

If you found it out of context for me to write something nice to you, well,
I will just have to wait for the next opportunity to mend my ways. Or I
could, right here, mention that virtually all cranksets using integrated
axles and outrider bearings have been tested substantially stiffer than any
square taper crankset. (Though I do not think we (little riders) really
want anything so extremely stiff.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

geeezz..takes a lot more to really get me riled up...thanks for the
info, whether or not Jobst will believe it is another thing
alltogether.

writes:

But when the same tire rolling along flat ground smashes
into a nasty bump, it meets the bump noticeably ahead of the
0 mph contact point--more face-first than with the sole of
its foot.

Doing a bit of trig, we get

(1) Vr = Vf*sqrt(2*h/R - h^2/R^2)

where

Vf = forward velocity (rider speed)
Vr = radial component of the velocity at collision,
that is, the component towards the hub (compressing the tire)
h = height of bump
R = radius of wheel.

For h R,

(2) Vr ~ Vf*sqrt(2*h/R)

I seem to recall that you have a Moulton. It struck me at
first that my notions predict that the smaller-wheel bike
should have more impact flats with the same rider and speed,
but I don't think that this is the case.

Maybe that will lead to some explanation of why my idea is
wrong? Or maybe the Moulton's suspension protects it?

First, Moultons have wide tires, about 1.2 inches. Second, I keep mine
pumped up hard, over 100psi---the Moulton (Jubilee) does not employ a
hooked bead rim but because the tires and wheels are made to a tight
spec, they can be run at high pressures. Third, as you suggest, I
believe that the suspension has a significant effect. I've put 10s of
thousands of miles on the Moulton, but have only had a one or two
pinch flats.

Consider a bicycle rolling onto a curb. The factors determining whether
a pinch flat occurs are probably

h = curb height
r = radius of corner of curb
w = tire width
p = tire pressure
R = wheel radius
m = mass (rider and bike)
V = velocity of rider

Other factors are tube characteristics (elasticity, ...), compliance
of system. Am I missing any obvious ones?


Joe

"Peter Cole" wrote in message
...
David Damerell wrote:
Quoting Tom Nakashima :

been there a few times myself. I was determine to learn
bicycle maintenance
and learn the correct way. I'm very pleased with the
information I've
gathered from Jobst and still use many of those methods and
suggestion
today. I have saved a lot of money and time working on my
bike, and have
had years of pleasurable riding experiences.


Not to make this all Jobst's fanclub, but he is the second on
the list of
people from whom I have learned the most about bicycles - the
first is
Sheldon. The things I have learned have been enormously
useful.

I have to agree about the learning, but I also find the NG
really boring
without Jobst.

Not so! The signature lines are enterainment enough. I am
learning to swear in French.

There are nuts of wisdom to be picked up in various places, much
of them old -- but still useful. My favorite bit of advice from
Jobst was that I could avoid breaking my cranks at the pedal eye
by counter-sinking and chamfering the opening and then
fabricating a matching conical washer to place between the crank
arm and pedal axle face. You know, after recouping the initial
cost of buying a Bridgeport mill, I expect to save a bundle on
cranks in the future. -- Jay Beattie.

"Jay Beattie" wrote in message
...


There are nuts of wisdom to be picked up in various places, much
of them old -- but still useful. My favorite bit of advice from
Jobst was that I could avoid breaking my cranks at the pedal eye
by counter-sinking and chamfering the opening and then
fabricating a matching conical washer to place between the crank
arm and pedal axle face. You know, after recouping the initial
cost of buying a Bridgeport mill, I expect to save a bundle on
cranks in the future. -- Jay Beattie.

You can actually save your money and do this with a hand drill motor and a
90 degree counter-sink tool.
-tom

Tom Nakashima wrote:
"Jay Beattie" wrote in message
...


There are nuts of wisdom to be picked up in various places, much
of them old -- but still useful. My favorite bit of advice from
Jobst was that I could avoid breaking my cranks at the pedal eye
by counter-sinking and chamfering the opening and then
fabricating a matching conical washer to place between the crank
arm and pedal axle face. You know, after recouping the initial
cost of buying a Bridgeport mill, I expect to save a bundle on
cranks in the future. -- Jay Beattie.


You can actually save your money and do this with a hand drill motor and a
90 degree counter-sink tool.
-tom



You gave me a good laugh, Jay.

I'm up to 175 lbs (76 kg) and have a 30 inch (76 cm) inseam, and I don't
expect to apply as much torque on my cranks as Jobst is, so I'll just be
taking my chances. So far, so good.


--
Tom Reingold
Noo Joizy
This email address works, but only for a short time.

"Tom Nakashima" wrote in message
...

"Jay Beattie" wrote in message
...


There are nuts of wisdom to be picked up in various places,
much
of them old -- but still useful. My favorite bit of advice
from
Jobst was that I could avoid breaking my cranks at the pedal
eye
by counter-sinking and chamfering the opening and then
fabricating a matching conical washer to place between the
crank
arm and pedal axle face. You know, after recouping the
initial
cost of buying a Bridgeport mill, I expect to save a bundle
on
cranks in the future. -- Jay Beattie.

You can actually save your money and do this with a hand drill
motor and a
90 degree counter-sink tool.

Tom, you must have incredibly steady hands. Plus, that still
leaves you with fabricating a conical split washer, with angles
matching the chamfer of the counter-sink. Try that with a hand
drill. Jobst if full of good information, but sometimes it is
like asking Einstein how to boil water -- you get instructions on
how to build a nuclear reactor.-- Jay Beattie.

On Wed, 03 Aug 2005 14:36:48 GMT, Joe Riel
wrote:

writes:

But when the same tire rolling along flat ground smashes
into a nasty bump, it meets the bump noticeably ahead of the
0 mph contact point--more face-first than with the sole of
its foot.

Doing a bit of trig, we get

(1) Vr = Vf*sqrt(2*h/R - h^2/R^2)

where

Vf = forward velocity (rider speed)
Vr = radial component of the velocity at collision,
that is, the component towards the hub (compressing the tire)
h = height of bump
R = radius of wheel.

For h R,

(2) Vr ~ Vf*sqrt(2*h/R)

I seem to recall that you have a Moulton. It struck me at
first that my notions predict that the smaller-wheel bike
should have more impact flats with the same rider and speed,
but I don't think that this is the case.

Maybe that will lead to some explanation of why my idea is
wrong? Or maybe the Moulton's suspension protects it?

First, Moultons have wide tires, about 1.2 inches. Second, I keep mine
pumped up hard, over 100psi---the Moulton (Jubilee) does not employ a
hooked bead rim but because the tires and wheels are made to a tight
spec, they can be run at high pressures. Third, as you suggest, I
believe that the suspension has a significant effect. I've put 10s of
thousands of miles on the Moulton, but have only had a one or two
pinch flats.

Consider a bicycle rolling onto a curb. The factors determining whether
a pinch flat occurs are probably

h = curb height
r = radius of corner of curb
w = tire width
p = tire pressure
R = wheel radius
m = mass (rider and bike)
V = velocity of rider

Other factors are tube characteristics (elasticity, ...), compliance
of system. Am I missing any obvious ones?

Joe

Dear Joe,

Doing a bit of trig, we get

(1) Vr = Vf*sqrt(2*h/R - h^2/R^2)

Er . . . yes, of course--obvious to the meanest
intelligence, just what I was thinking myself!

[Counts on fingers, forgets to carry the two, wonders what
Joe would consider more than a bit of trig?]

Concerning the Moulton, I wonder if the modern hooked-bead
rim is any more likely to cause pinch flats than the older
kind used by the Moulton? I suppose that a hooked-bead
clincher-rim is even further from a tubular-rim than a
smooth clincher-rim.

That leads to what will probably be missing from any
equation--exactly how does the tire/tube fold and crush
toward the rim? The way that a tire bead mounts on a
clincher might affect this, as well as whether the bead is
Kevalr or steel.

What will probably determine the outcome at a given speed,
mass, inflation, tire size, and so forth is the actual shape
of the nasty bump, its width, and its length. Even the
idealized curb varies in height and the radius (or
sharpness) of its lip.

A big chunk of gravel, the next cobblestone waiting at the
end of the channel between two cobblestones, the scrap of
2x4, the piece of muffler, and all the other hazards on the
road are likely to be too irregular to predict, even if they
were kind enough to hit the tire at the same height and
angle.

An I-beam hit end-on, for example, might well produce
different folding according to its height and surprise us by
being deadly at a low height, but strangely impotent when
higher.

Similarly, the same I-beam might flat more tires when narrow
than when wide. Remember, there are plenty of posts about
tires surviving impacts that bent rims. A post from 42 in
this thread mentions an open manhole that failed to flat his
tire. (Other riders could dolefully testify to impact flats
from some piece of debris that was so small that they didn't
see it in the first place and couldn't find it when they
searched for it.)

[Scurries off to work painfully through "a bit of trig".]

Carl Fogel

On 3 Aug 2005 06:06:57 -0700, "41"
wrote:


wrote:
On 2 Aug 2005 23:18:33 -0700, "41"
wrote:

wrote:
On 2 Aug 2005 20:50:35 -0700, "41"
wrote:

The article
descri bes all the beer drinking fans and while conventional high
caliber road races may have the course swept beforehand that clearl y
can't be done on such routes. How many decades of sharp detritus must
have accumulated there?f

Dear 41,

Of c ourse!

The beer drinking fans have caused all those flats on
Paris-Roubaix!

Oh, at least some:

http://www.cervelo.com/athletes/paris-roubaix.html
http://tinyurl.com/8tw9k

[snip]

Dear 41,

"Th en I flatted [1], I quickly switched bikes (much faster
than a wheel change) and chased back to the group. I felt
very strong and started pulling and pulling at the front,
until only a select group of riders was left. Then I flatted
again [2], swi tched bikes again, and chased back to the
group for the third time. By this time three leaders were up
ahead with 25k to go, and together with Van Petegem I tried
to jump across. Just before we caught the leaders I flatted
again [3]. Now I switche d to my spare Soloist, rode 200m and
flatted again!! [4] Somebody had broken a glass bottle on
the cobbles!"

http://www.cervelo.com/athletes/paris-roubaix.html

Er, what do you think caused the 1999 winner's first three
flats before the gla ss?

Er, what makes you think he pinch flatted? Read your own descriptions
of the experience and think about what type of impact is required to
pinch flat a 25mm+ tire. This is not what he describes. But do read
about the infamous debris that accumulates in the pavé and how the
often wet weather makes it even more effective.

I notice you conveniently ignored everything else I posted that also
"flatly" contradicts your belief.

Dear 41,

Heavens, no! I read it with deep appreciation!

You've utterly convinced me that all the professional riders
and reporters who insist that impact flats have been a
common problem on Paris-Roubaix for a century are spreading
myth and lore for purposes too terrible to contemplate.

I'm certain that he ran over a quill from a French porcupine
for the first flat, a needle from a Belgian cactus for the
second flat, and a piece of WW2 shrapnel for the third flat.

These hazards are so common on Paris-Roubaix that the 1999
winner thought them not worth mentioning--it was the glass
that startled him and required description.

Imagine how amazed he would have been if he had read your
posts and then discovered to his horror a pinch-flat!

The shock of a pinch-flat on the cobblestones where he was
assured that he would be safe from them might have killed
the poor fellow!

I look forward eagerly to your campaign to repave asphalt
and concrete bicycle paths with cobblestones to reduce the
dangers of impact flats.

Carl Fogel

"Jay Beattie" wrote in message
...

"Tom Nakashima" wrote in message
...

"Jay Beattie" wrote in message
...


There are nuts of wisdom to be picked up in various places,
much
of them old -- but still useful. My favorite bit of advice
from
Jobst was that I could avoid breaking my cranks at the pedal
eye
by counter-sinking and chamfering the opening and then
fabricating a matching conical washer to place between the
crank
arm and pedal axle face. You know, after recouping the
initial
cost of buying a Bridgeport mill, I expect to save a bundle
on
cranks in the future. -- Jay Beattie.

You can actually save your money and do this with a hand drill
motor and a
90 degree counter-sink tool.

Tom, you must have incredibly steady hands. Plus, that still
leaves you with fabricating a conical split washer, with angles
matching the chamfer of the counter-sink. Try that with a hand
drill. Jobst if full of good information, but sometimes it is
like asking Einstein how to boil water -- you get instructions on
how to build a nuclear reactor.-- Jay Beattie.

Jay, I have worked in a machine shop here at SLAC, we have plenty of
Bridgeport mills here.
I thought you would know that the counter sink follows the hole diameter.
All you have to do is make sure the crank is clamped down secure, then use a
handheld drill motor.
Or use a drill press and have the crank free....one or the other has to be
secure to chamfer tool. The chamfer counter sinks come in two angles that I
know of 82 degrees for flat head screws, and 90 degrees for deburring. Try
it sometime Jay, take a drilled hole in alum, say 1/2" dia. 3/4" thick,
then chamfer the hole using a 90 degree counter sink and handheld drill
motor.

On Jobst postings, just extract what you need, the info is there.
-tom

On Wed, 03 Aug 2005 09:31:20 +0200, Lou Holtman
wrote:

wrote:

If I seem too skeptical of Jobst's lower-speed claims, it's
partly because I doubt that my daily "descent" that often
reaches 40-50 mph at 5,000 feet on the western edge of the
Great Plains matches what Tour de France riders achieve on
Alpine passes at higher altitudes.

I rarely reach speeds over 80 km/hr in the Alpes and the Dolomites,.
There is always some traffic, hairpins, bad pavement etc. etc. that
slows me down. My maximum speed in this years Maratona dles Dolomiti
(http://www.maratona.it/home.php) was 76.3 km/hr. In that race the roads
are closed for all traffic so I could cut corners and so on. Still only
76.3 km/hr and I was overtaking a lot of people in the descents.


Lou


Dear Lou,

Again, no offense intended, but the 147 km long course of
that mass "marathon" event has been won for the last three
years not by any professional, but by an ex-professional,
Emanuele Negrini. His top speed might be interesting.

I may be wrong, but I suspect that the actual pros mentioned
as celebrities on that page are too sporting to enter this
charity event and actually compete.


In any case, it would be surprising if you didn't overtake a
lot of people--the course was closed to other traffic, but
there were 8,690 other riders on the road with you in 2005.

In 2001, according to the last age-table, over half the
7,284 riders were 40 to 78 years old. Less than 10% were
under 30. There were about as many riders 65 and over as
there were riders 20 and under.

I hope that it was as much fun as it sounds, but it may not
be the best indicator of the speeds that pros in the Tour de
France achieve downhill.

Carl Fogel

No I'm not offended Carl.
But I don't see why older fun riders can't reach the same speed on
descents as pro riders do. They ride the same bikes, the ride the same
descents and some of them have the same guts.

I believe that a top speed 100 km/hr is rare in the pro peleton.
Possible? Sure, but not on the Galibier.


Lou

Dear Lou,

One reason why fun riders aren't likely to reach the same
downhill speeds as pros who are racing is acceleration.

On a tight, twisty descent, the rider comes out of a turn
after braking heavily.

The fun rider pedals a little, but probably lets gravity do
most of the work and just coasts faster and faster down the
next straight. Long before he reaches terminal velocity, he
starts braking for the next turn.

The pro racing downhill (as opposed to cruising) would pedal
hard out of the turn and leave the fun rider well behind at
the beginning of the straight. He'd get a lot closer to
terminal velocity than the fun rider, even if they both
began braking at the same point.

And despite what a lot of fun riders think, the pros may not
be braking quite as early as they do.

Of course, the pros might be just loafing along, compared to
what they can do. That's the only way that most of us
actually keep them in sight.

Unfortunately, this can lead some of us to the mistaken
conclusion that we can keep up pretty well with the pros,
just as a lot of amateurs form strange notions if allowed to
take infield practice with major league players.

Again, no offense is intended. When I was a teenager, I was
lucky enough to ride trials motorcycles in a club that spent
a lot of time and trouble coaxing the best possible riders
from Europe to visit and show us what they could do.
Watching retired visitors who could no longer compete in
Europe stomp the best Colorado and California riders flat in
trials (and then blast past them on stock machines between
sections) taught me that there's usually a significant
difference between pros and amateurs.

I suspect that a real race down a steep, twisty pass would
favor the pro over the amateur. It's mostly amateurs who
develop the interesting notion that they operate at the same
level as the pros. Why they don't enter the races and win
them remains a mystery.

Carl Fogel