On Sat, 28 Feb 2004 01:57:01 GMT,
[email protected]
wrote:
>John Dacey writes:
>> These claims for lowered rolling resistance recur here sporadically, but they never seem to
>> include supporting documentation to quantify them.
>
>You can see the difference on the graphs that have been explained often here. The tubulars that
>have the best RR by their nature (flattest curve) lie higher than clinchers due to glue squirm.
>That this is the case should be obvious when inspecting rims that have been ridden a lot. They have
>base tape wear marks and the glue is full of grey aluminum wear dust.
>
>
http://www.terrymorse.com/bike/imgs/rolres.gif
You say I can see the difference, but I don't. There's no mention of the kind of adhesive used
for the two tubular models in the results you cite. Where does the plot lie for tires with a
hard cement?
>
>> Isn't it time we learned whether we're talking about picoseconds per kilometer or if glue
>> selection for track racers really merits more consideration than it currently receives?
>
>It is significant enough that the ancients in the days of tubulars invented hard glue to get rid of
>this parasitic loss for record events on the track. It took me a few seconds to recognize this on
>seeing the curves in these rolling resistance tests. Besides, around here riders often wore through
>the base tape from all the creep on road glue from Pirelli, Clement, D'Allesandro' Tubasti,
>Pastali, etc.
It seems to me that your "recognition" of this is conjecture, inasmuch as the tubular results with
hard glue aren't actually included on the graph. Also, from the recitation of the brands of cements
on which your comments are derived, it's clear that you're opinions are based upon products of 25
years ago and perhaps not consistent with results that might be had from contemporary tire adhesives
from Continental, Vittoria, Soyo and 3M. The "squirminess" of Tubasti is probably much greater than
for Mastik One.
The Ancients, whom you credit with inventing hard glue for select track events are the same ones who
began the custom of inflating those tires to very high pressures; yet you've regularly described
high pressure as gratuitous excess. High (10+ BAR) pressure for track tubulars remains a common
practice, while using shellac and track-specific tubular cement is rarely (if ever) still done. Why
would one bit of ancient wisdom that you say is significant (hard glue) fall from use while another
that you regard as needless risk (high pressure) remain common practice unless people found rewards
with the one and none in the other?
>
>I was grateful to the Specialized Touring-II tire that absolved me of messing with tubulars. Those
>FAQ items on manufacture, repair and gluing of tubulars did not come from empirical thinking. That
>was a lot of impractical tire repair... a pain in the ass.
I don't want to resurrect the whole clincher/tubular debate. The original poster inquired about
track tires, where tubulars are still the predominant format. I request again: can you estimate the
time difference in a flying kilometer time trial ridden at 50kph, where the only difference is
whether shellac or modern road rim cement is used to adhere the tires? Just how many seconds (or
fractions thereof) per kilometer is shellac (track glue) likely to be worth?
-------------------------------
John Dacey Business Cycles, Miami, Florida
http://www.businesscycles.com Now in our twenty-first
year. Our catalog of track equipment: eighth year online
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