[email protected] wrote:
> Extrapolation in this event is purely hypothesis since you are
> extrapolating extrapolated data that does not fit a curve.
Nonsense. Distilled down, all you're saying is that you refuse to
accept the applicability of the test data to the real world. It's
incontrovertible- Vittoria is as strong at 60o as 3M is at 27o. Ignore
or deride it if it makes you feel better but since you don't ride
tubulars it hardly matters. For those who do, though, the conclusion to
be drawn is important and obvious.
> > It is an attempt to summarize the test results that show Vittoria to
> > retain considerable strength at 60oC, based on the assumption that
> > the strength of 3M at 27o is also safe, and since strength of 3M@27o
> > = strength of Vittoria@60o, Vittoria is safe at 60o. Are you really
> > so dense that you cannot fill in the omitted steps yourself?
>
> You have no indication of whether the glue would allow tire creep on a
> descent.
To believe that it would, you would have to hypothesize that tire creep
occurs without rim heating, since Vittoria at 60o has strength
equivalent to 3M at 27o.
> That occurs long before you can lift the tire from the rim
> when glue softens. As I said, these folks have no experience in the
> matter they are trying to define and missed the appropriate test
> method. Tires rolling off rims is not the critical mode of failure,
> but rather valve stem separation as the tire creeps on the rim.
It is an operational definition of bond strength, and that is what they
are testing. If one glue is twice as strong as another, it will resist
tire creep or roll-off better than the weaker glue.
> > Yes, we know. Your anecdotes are well documented here. Your hard
> > data is quite sparse, though.
>
> Watch out, you can overuse disparaging words. I see your word of the
> day is anecdote. Don't wear it out.
Anecdote, anecdote, anecdotal. Your argument in this thread is based on
a combination of anecdotal evidence and faulty and purposefully
misleading reasoning.
> > We all have our anecdotes, but when it comes to hard data, the papers I
> > referenced trump anecdote. You have some hard data about temperatures
> > commonly attained in Alpine descents and glue strength, how about
> > presenting *it* ?
>
> How hard must the data be. I have sheared off about six or eight
> valve stems and blown four clinchers off the rim from brake heating.
What temperature, and measured how? What glue? What is its strength
relative to Vittoria at that temperature? What is the relevance of
clinchers to this discussion except to support my contention that you
have achieved extreme rim temperatures that are uncommon to even
experienced cyclists?
> Besides that, people with whom I have ridden had similar incidents.
> On the 9other hand you keep referring to a bench test that tried to
> place some numerical value on pull-off force that is not the critical
> parameter.
All I have claimed in this thread is that there is a significant
difference between glues at 60o, and that it could provide a critical
safety factor for riders whose rims heat to that temperature..
> > No one knows what happens over 60o, but only a liar would try to argue
> > that we need data points between 27o and 60o WRT Vittoria- it's safe at
> > 27 and it's safe at 60; we know it's safe at all temperatures in
> > between.
>
> I see you are grasping for straws as you allude to lies.
No, I'm calling you a liar. You feel the need to protect your ego and
reputation by distorting the meaning and conclusions from this study.
Your distortions are in essence lies, because they are not made
inadvertently or out of ignorance.
> How is it
> that these technical discussions end in rude name calling.
See above.
> I see no
> evidence that you have unearthed in your riding that makes any of your
> claims more than conjecture. I have my road tests and results that
> you prefer to ignore and call anecdotes.
They are not controlled studies, they are made without any measuring
instruments, they were not repeated in a controlled setting. They are
anecdotal at best, and you know damn well that that is what they would
be called under any type of peer review.
> > Well, of course it does change. We don't know the altitude at which
> > you noted said sizzle, therefore the boiling point of water is a
> > significant undefined variable. But the real point I was trying to
> > make is that noting water sizzling on your wheel does not provide
> > the slightest shred of evidence that such sizzling would be
> > commonplace in descents. You admitted in this ng that the
> > circumstance was descending on high altitude unpaved Alpine roads.
> > That is an extreme situation beyond the experience of of the great
> > majority of tubular riders.
>
> I think you don't understand steam generation. It is more than sizzle
> and the heat of vaporization is enough to raise the temperature of a
> rim substantially above 100 degrees C in the absence of steam
> generation. Are you aware of heat of vaporization?
In the absence of a thermometer, said sizzle does not provide evidence
of a temperature beyond 100o, and probably not even that, since your
Alpine adventures presumably involved considerable altitude. (Note that
I did not say anything about "steam".)
> >> The point is that this is a typical descent of which we have many
> >> right here in the Santa Cruz Mountains except that I never had the
> >> opportunity to descend them with water in the rim.
>
> > Unpaved? Get an MTB! But don't tell us that making a ride like
> > that on tubulars is proof that tubulars are unsafe on normal
> > mountain roads.
>
> I don't know where you get that but these effects were experienced
> primarily on paved roads.
Well, I guess I got it from this: "I refers only to that you have
apparently not had enough experience with them under demanding
conditions to realize the hazards they pose. This was even worse in
the days before 1970, when many Alpine passes were unpaved and
descending then meant riding the brakes for long durations, high speed
and especially high speed cornering was not possible although the
grades were just as steep as thy are today."
> Paved or unpaved has no effect on rim glue
> although the curves and road surface affect how fast one can let the
> bicycle roll.
Exactly, and that was the context of your above content. Unpaved roads
require lower speeds and more brake use because you cannot safely
maintain terminal velocity.
> Typically, steep paved roads such as the ones in this
> area and on the Sierra like Old Priest Grade, melt rim glue regardless
> of the weight or skill of the rider.
Steepness is certainly a factor, as are weight and skill of the rider,
and frequency and sharpness of curves. Another factor is the glue
itself. They are all variables that contribute to rim heating from
braking. It is absurd to try to roll all these factors into a single
off/on dimension that protrays glue selection as unimportant and
tubulars inherently unsafe in mountain riding.
> You may call this anecdote but you ignore the irrefutable evidence my
> observations reveal and that they are good and reliable
> characterization of physical phenomena that affect the safety of
> tubular tires.
Uncontrolled and unmeasured observations are the very definition of
anecdote.
> Not all research is done in lab coats and indoors. If
> you prefer to have someone in a laboratory with a thermometer to tell
> you that tubular rim glue presents no problems with respect to braking
> heat, that is your prerogative.
I don't make that claim. On the contrary, the controlled research shows
the exact opposite, that there can be significant issues with glue
weakening from rim heating. But it also shows clearly that one glue in
particular has a significant advantage over all the others in resisting
this problem.
> I don't see that you should lend it
> any endorsement if you haven't tried it on the road to see if the test
> data has any relation to performance.
I have tried it on the street, and I can attest that it makes an
extremely strong bond on the rim as shown in their testing at normal
temperature; however, since I have never had an issue with tire creep
under any circumstances, and I don't ride mountains these days, I
couldn't comment on that part of their test. But then, you don't have
any experience with it on the road, either, that would allow you to
contradict the test data, which stands on its own.
> It would be good if you could explain what changed since then and why
> you believe that all the problems with tubulars have been solved in a
> time when they are no longer used by most riders.
The majority of racers at the highest level still use tubulars. That
alone is reason to expect that there would continue to be technological
advance as there has been in every other aspect of racing bicycle
technology over the last 20 years. Furthermore, if you had continued to
use tubulars you might have gained experience with Vittoria glue in
particular. I would ask why you would have us believe that technology
has NOT advanced in the last twenty years when it has everywhere else.
