Q. Will I benefit from different tire size or type?

On 3 Aug 2003 13:44:45 -0700, (Joe Samangitak)
wrote:

Thanks to all who have offered very helpful responses, I now have a
much better idea of what tire I need for my city driving -- and the
advantages are towards wider tires, so my next tire will not be any
skinnier than the 700 x 35 I already have. I am even thinking I might
prefer a 700 x 40. I definitely value comfort and safety over speed
(although I do a lot of stop and starts as well, because of traffic
lights at every block). I guess no one can tell me if a 700 x 40 would
be more suited to my needs as I've outlined, so I'm gong to try to get
a mountain bike to ride.

NOW FOR THE TIRE! I will accept minimal siping if I can't locally find
a "full slick" in the 700 x 35/40 size I need. The Michelin Transworld
City I mentioned
(http://cycleus.webmichelin.com/tires/transworldcity.htm) seems to
have some pretty -deep- siping though (the only flat part is a narrow
strip of tread in the center). So I'm not sure if its the best choice
for safety's sake on pavement. Any better recommendations for COMMONLY
AVAILABLE tires, around the same price as the Michelin, that may be
"more slick" and thus provide better road contact on the pavement? (I
don't know if I can get the IRC or Avocet brands locally; but I know
for sure I can get Continental, Hutchinson, Panaracer, Michelin,
Vittoria, etc).

I have the Continental Travel Contact in 26" on a city commuter
mountain-type bike and have been very happy with it. I see that they
make a 700x37...

http://www.conti-online.com/generato...ontact_en.html

There is a large center patch that is a slick for all intents and
purposes. And when I go off-road (sort of, light off-road only with
these), I can drop the pressure and get a little traction from the
side knobs; nice to have that option. At first I was worried that I
would be riding on the knobs in turns on the road, but that hasn't
happened. I'd have to be making some fast turns at a good angle to hit
the knobs, and I don't ride this bike that hard.

It is heavy, but rides very nicely. In 700 miles I notice almost no
wear front or back. It took 500 miles just to wear off the center
molding ridge on the back wheel. And I haven't had a flat yet. By
changing the pressure, you can change the feel of the tire. After
looking at a variety of smooth tread tires with some off-road ability,
these seemed to be the best tread design I could find, and I am very
happy with them.

On Sat, 2 Aug 2003 21:34:08 -0500, A Muzi wrote:
of pavement anomalies. Keep the pressure up always but especially if you
go to a skinnier tire.

In fact, the reason to go to a skinnier tire, afaik, is to
be able to use a higher pressure.

I recall a thread that discussed rolling resistance; and
some studies or experiments or something determined that
all things being equal (pressure, tread, compound, bike,
rider, temp, humidity, etc), a wider tire actually has
less rolling resistance. The real-world result, however,
was that narrower tires had lower rolling resistance due
to the higher pressures you could use.

Does anybody else remember that? I don't think it was on
these rec.bicycles newsfroups, but I can't imagine where
it WAS if that's the case.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
--
Rick Onanian

On Sun, 03 Aug 2003 17:50:48 GMT, OliverS
wrote:
However, knobbies take a bit toll on efficiency -- my guess based on my
personal performance experienc (somewhat subjective to be sure) about
25%.

The exception to that rule being knobbies with a centerline.
Such tires tend to be okay, and are often designed to turn
pretty well on pavement too.

Still, you're much better off with a slick or even a
semi-slick, and there's no reason whatsoever to use
a knobby unless you're doing moderate-to-heavy off-road
riding -- more than just dirt paths, grass, and unpaved
sections.

--
Rick Onanian

Does it not make sense that the fatter tire will have more rolling
resistance because the contact patch (and thus friction) will be greater
with the fatter tire? If you look at vehicles built for straight-line speed
(other than those where massive power needs to be transmitted to the
ground - definitely NOT bikes) be it soap-box racers to land speed record
assault rocket cars, the tires are hard and skinny to minimize rolling
resistance.

--

- GRL

"It's good to want things."

Steve Barr (philosopher, poet, humorist, chemist,
Visual Basic programmer)
"Rick Onanian" wrote in message
news
On Sat, 2 Aug 2003 21:34:08 -0500, A Muzi wrote:
of pavement anomalies. Keep the pressure up always but especially if you
go to a skinnier tire.

In fact, the reason to go to a skinnier tire, afaik, is to
be able to use a higher pressure.

I recall a thread that discussed rolling resistance; and
some studies or experiments or something determined that
all things being equal (pressure, tread, compound, bike,
rider, temp, humidity, etc), a wider tire actually has
less rolling resistance. The real-world result, however,
was that narrower tires had lower rolling resistance due
to the higher pressures you could use.

Does anybody else remember that? I don't think it was on
these rec.bicycles newsfroups, but I can't imagine where
it WAS if that's the case.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
--
Rick Onanian

"GRL" wrote in message
...
Does it not make sense that the fatter tire will have more rolling
resistance because the contact patch (and thus friction) will be greater
with the fatter tire?


Not necessarily. At a given tire pressure and weight, the contact patch is
*the same size*, no matter how wide (up to a point). Think PSI. Pounds per
sq inch.
A 200lb rider/bike creates a 2 sq in patch for a bike tire pumped to 100
psi. No matter what the width or diameter.

The contact patch will be a different shape for a wider vs skinnier tire.
Wide and short, instead of long and skinny. Less sidewall deformation as the
tire rolls.

This is, of course, making the huge assumption that all other factors are
equal (Tire construction, TPI , pressure, etc).

Width (wind resistance) may overcome the difference in Crr.

If you look at vehicles built for straight-line speed
(other than those where massive power needs to be transmitted to the
ground - definitely NOT bikes) be it soap-box racers to land speed record
assault rocket cars, the tires are hard and skinny to minimize rolling
resistance.

They are also skinny to minimise frontal area/wind resistance. Those types
of vehicles also do not have to worry about wear, traction in varying
conditions, marketing costs, etc.

Several tire rr tests have been done in the recumbent community.
http://www.beezodogsplace.com/Pages/...Resistance.pdf
http://www.legslarry.beerdrinkers.co.uk/tech/GS.htm

Pete

On Thu, 7 Aug 2003 20:08:29 -0400, GRL wrote:

Does it not make sense that the fatter tire will have more rolling
resistance because the contact patch (and thus friction) will be greater
with the fatter tire?

I thought this too, but I now believe that I was incorrect.

See http://www.sheldonbrown.com/tires.html#width

If you look at vehicles built for straight-line speed
(other than those where massive power needs to be transmitted to the
ground - definitely NOT bikes) be it soap-box racers to land speed record
assault rocket cars, the tires are hard and skinny to minimize rolling
resistance.

The narrow tires are more aerodynamic and can take higher pressures.

--
Rick Onanian

"Rick Onanian" wrote in message
news
On Fri, 08 Aug 2003 01:08:40 GMT, Pete wrote:
A 200lb rider/bike creates a 2 sq in patch for a bike tire pumped to 100
psi. No matter what the width or diameter.

Close. Actually, this would be correct:
A 200lb rider/unicycle creates a 2 sq in patch for a unicycle
tire pumped to 100 psi. No matter what the width or diameter.

Forgot that some of the rider's weight is on the _other_
bicycle tire?


ok, ok

But the concept still stands.

Pete