Re: [CR]Tire Direction --> ???

(Example: Framebuilding:Brazing Technique)

In-Reply-To: <18995.45437.qm@web50212.mail.re2.yahoo.com>
References: <18995.45437.qm@web50212.mail.re2.yahoo.com>
Date: Mon, 31 Mar 2008 17:33:13 -0800
To: John Barry <usazorro@yahoo.com>, classicrendezvous@bikelist.org
From: "Jan Heine" <heine94@earthlink.net>
Subject: Re: [CR]Tire Direction --> ???


At 5:00 PM -0700 3/31/08, John Barry wrote:
>Sounds like another shot-from-the-hip Jobst theory.
>
>Anyone who has driven on good tires on a wet road, and
>then driven on bald ones on a wet road and not noticed
>a difference, would have to be either very distracted,
>or borderline comatose.
>
>Hydroplaning is a very real phenomenon,

In cars, hydroplaning is a real problem, because the contact patch is very large. (Car tires run at low pressures compared to bicycle tires.) A bicycle's contact patch is too small to hydroplane. (Semi-trucks also have much less of an issue with hydroplaning, as they are so heavy.)

So it is safe to say that hydroplaning is not an issue with bicycles.

However, I have noticed that bald bicycle tires do appear to slip more easily on some wet roads. For example, the latest Avocet tires are terrible in the wet. This could be due to the rubber compound, but I suspect something else is at work here:

Roads are most slippery when it has not rained in a while, and there is a film of oil/dust/grime on the surface. Once a few days of vigorous rain have washed the roads clear, traction is much improved.

Now, could a bicycle tire with a fine tread cut through that very thin layer of grime/dust/oil and find traction where a bald tire would ride on top and slip?

Jobst et al., who say that bicycle do not hydroplane, are correct. However, their conclusion that tread does not make a difference may be wrong... because as so often, they look at the wrong problem.

I am thinking of a way to test this hypothesis. Obviously, we'd have to test the same type of tire, one with new tread, the other with the tread worn/sanded off. But how do we test without risking life and limb?

In the mean time, I see no harm done in a fine file tread - and it looks nice, too - so I am going with that for now.

(The best tire may be a somewhat worn one, with less tread in the center, and more on the edges. So you get better traction when cornering than on the straights.)

Jan Heine
Editor
Bicycle Quarterly
140 Lakeside Ave #C
Seattle WA 98122
http://www.bikequarterly.com