Re: [CR]Re: Tubulars vs. clinchers; Was: "Q" and other mythology.

(Example: Framebuilding:Brazing Technique)

Date: Tue, 04 Nov 2008 21:29:10 +0000 (GMT)
From: <gholl@optonline.net>
Subject: Re: [CR]Re: Tubulars vs. clinchers; Was: "Q" and other mythology.
In-reply-to: <a0623096ac53649538635@[192.168.1.34]>
To: Jan Heine <heine94@earthlink.net>
References:
cc: Classic Rendezvous <classicrendezvous@bikelist.org>

Since at least two of these tires appear to be "On Topic," I gather this is suitable for discussion here. Perhaps I missed something, but, could someone enlighten me as to the exact nature of these "fast tire" tests?
Thanks,
George
George Hollenberg MD
CT, USA


----- Original Message -----
From: "Jan Heine"
Date: Tue, 04 Nov 2008 03:31:00 -0000
Subject: [CR]Re: Tubulars vs. clinchers; Was: "Q" and other mythology.
To: billydavid13@comcast.net, classicrendezvous@bikelist.org


> At 4:01 PM +0000 11/4/08, billydavid13@comcast.net wrote:
>
> >My guru in a
> >ll things technical, Jan Heine, makes good arguments for sewups
> being faste
> >r in BQ and i buy them. My point is that despite all the hype
> and measureme
> >nts purporting to show clinchers being faster, racers "vote w/
> their feet"
> >by choosing tubulars.
>
> Sorry, there is a misunderstanding. Our real-road tests seem to
> indicate that clinchers are slightly faster than tubulars.
>
> We ran three tires that were sort-of-similar:
>
> - Clement Criterium tubulars (one silk, one polyester), 21.5 mm wide
> - Deda Tre Giro d'Italia clincher (made in the same
> Clement/Challenge
> factory as later Clements), 24.5 mm wide
> - Clement Campionato del Mondo tubulars (polyester), 28 mm wide
>
> All of these tires appear to use similar casings. It is possible
> that
> the Del Mondos use a slightly coarser (less tpi) casing.
>
> Note that wider tires were slightly faster in our tests. We
> tested 3
> Michelin Pro2 Race tires, and the 25 mm was fastest, the 21 mm
> (nominal: 20 mm) slowest. So you'd expect the Campionato del
> Mondo to
> be fastest, all things being equal.
>
> The times were
>
> - Criterium: 27.4 seconds
> - Deda: 25.3 seconds
> - Del Mondo: 25.5 seconds
>
> So it's clear that the Criteriums are slower. Part of that is
> because
> they are so narrow (the 25 mm Michelins were 0.6 seconds faster
> than
> the 21 mm wide ones). Part of that is the "sew-up penalty." The
> Del
> Mondos were statistically the same speed as the Dedas, even
> though
> they are a lot wider. Again, there appears to be a slight "sewup
> penalty."
>
> However, in tests on steel drums, the "sewup penalty" is much
> greater, because the improved comfort (less vibration of the
> bike)
> does not come into play.
>
> So the fastest tire, in theory, would be a Campionato del Mondo
> clincher, but the difference clincher-tubular isn't all that
> great.
> Racers would do well to use 28 mm tubulars instead of 21-23 mm
> wide
> ones.
>
> We also found that unlike the clinchers we tested, the sewups
> actually became slower when we inflated them very hard. The
> Criteriums were faster at 105 psi than at 130 psi. The Del
> Mondos
> were faster at 85 psi than at 105 psi. Of course, this depends a
> bit
> on the road surface - on very smooth roads or the track, higher
> pressures probably offer more of an advantage.
>
> The biggest problem is that what feels fast and what is fast are
> two
> different things with tires. We associate higher frequencies of
> vibrations with faster - the faster you go, the quicker you hit
> the
> road irregularities.
>
> However, using a narrower tire at higher pressures also gives
> you
> higher frequencies, and thus tricks you into feeling faster even
> if
> you aren't. This still works for me - whenever I ride narrow
> tires, I
> feel super-fast. Then I ask Mark, who is riding next to me on
> his
> usual 650B x 38 mm tires whether we are going faster than usual,
> and
> the answer always is "No." Tricked again!
>
> Jan Heine
> Editor
> Bicycle Quarterly
> 140 Lakeside Ave #C
> Seattle WA 98122
> http://www.bikequarterly.com
> --
> _______________________________________________
>

George Hollenberg MD
CT, USA