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

[Joe Samangitak]

I have 700 x 35 tires on my hybrid bike, and I've recently learned
that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
Question is, do I want to? I ride exclusively on pavement in a city,
so I'd like to maximize tire efficiency for this type of driving.

- First of all, will it work to put different width tires on my
hybrid/city bike, or is there an issue with narrower widths coming off
the rim, etc.?

- Secondly, is there an advantage to using a different tire size if I
can, or should I assume the original 700 x 35 tire size was already
designed ideally for city driving?

- Lastly, I read expert testimonials that said slick tires are best
for pavement riding, cornering, wet driving, traction and have less
rolling resistance, basically because more rubber contacts the road. I
was looking to buy the Michelin Transworld City, but its not a pure
bald slick, it has fairly deep recesses, presumably to siphon off
water (which I read isn't necessary for bike tires, and that this
system doesn't work better than slicks). So my question is, would I be
better off driving in my city with a pure bald slick, such as the
Avocet Road 20, instead of the Michelin Transworld City? Or is it even
better to use DIFFERENT TIRES for the front and back? Any commonly
known disadvantages to going with pure bald untreaded slicks on
pavement, such as premature tire wear, as compared against tires with
a tread?

[A Muzi]

"Joe Samangitak" > wrote in message
om...
> I have 700 x 35 tires on my hybrid bike, and I've recently learned
> that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
> Question is, do I want to? I ride exclusively on pavement in a city,
> so I'd like to maximize tire efficiency for this type of driving.
>
> - First of all, will it work to put different width tires on my
> hybrid/city bike, or is there an issue with narrower widths coming off
> the rim, etc.?
>
> - Secondly, is there an advantage to using a different tire size if I
> can, or should I assume the original 700 x 35 tire size was already
> designed ideally for city driving?
>
> - Lastly, I read expert testimonials that said slick tires are best
> for pavement riding, cornering, wet driving, traction and have less
> rolling resistance, basically because more rubber contacts the road. I
> was looking to buy the Michelin Transworld City, but its not a pure
> bald slick, it has fairly deep recesses, presumably to siphon off
> water (which I read isn't necessary for bike tires, and that this
> system doesn't work better than slicks). So my question is, would I be
> better off driving in my city with a pure bald slick, such as the
> Avocet Road 20, instead of the Michelin Transworld City? Or is it even
> better to use DIFFERENT TIRES for the front and back? Any commonly
> known disadvantages to going with pure bald untreaded slicks on
> pavement, such as premature tire wear, as compared against tires with
> a tread?

Yes you can switch widths within broad limits ( A 700-47 will probably not
clear your frame and a 700-20 won't last a day on a wide rim). On most fat
700 rims a 32 through 38 are fine. I do not know your rim model so I can't
say what the limits are. If your dealer has a clue s/he should be able to
make a recomendation. Do you want faster? Tougher? A softer ride? The
ability to better corner agressively?

Tread is completely irrelevant on a paved surface.

The Michelin Transworld City is a great urban tire, I like them lots more
than the cheap knobby o.e.m. tires on $300~$500 bikes. They're long-wearing
and smoother riding. That said, the siping is only there to pander to
customers' misunderstandings of tires and treads. Smooth would have been
better and Michelin knows it. They are made in 700-35, 700-32 and 700-28 .
There's theoretically a 700-40 that is perenially on backorder if they ever
made them at all. ( and a nice fat 700-47 that may not be useful to you)

Other popular tires for your bike are Inoue-IRC's Metro 700-38 on the fat
side, Panaracer Pasela 700-35 for a medium tire and the wonderfully fast
IRC Tandem 30 if you are not a heavy or abusive rider and your route is free
of pavement anomalies. Keep the pressure up always but especially if you go
to a skinnier tire.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

[Werehatrack]

On 2 Aug 2003 19:19:02 -0700, (Joe Samangitak)
may have said:

>- First of all, will it work to put different width tires on my
>hybrid/city bike, or is there an issue with narrower widths coming off
>the rim, etc.?

Not knowing the rim width, it's hard to say what range of sizes will
work well. You may be able to go down a few sizes, but do you want
to? Less rubber between the road and the rim can yield a harsher ride
and an increased probability of punctures.

>- Secondly, is there an advantage to using a different tire size if I
>can, or should I assume the original 700 x 35 tire size was already
>designed ideally for city driving?

Make no unwarranted assumptions; the size could have been chosen for
any number of reasons that may or may not be relevant to you. All
that you can likely assume is that 700x35 is a safe size to use on
your rims.

>- Lastly, I read expert testimonials that said slick tires are best
>for pavement riding, cornering, wet driving, traction and have less
>rolling resistance, basically because more rubber contacts the road.

For bicycles, that's pretty much true. Unlike motor vehicle tires,
where the tread is essential to prevent aquaplaning due to the large
size of the contact patch, a 700x35 bike tire has a small enough patch
(and is typically used at a low enough speed) that the aquaplaning
issue simply doesn't apply. While there are some who will state that
a treaded tire will not slip as easily on a damp polished concrete
surface (which is inherently treacherous territory), it's been my
experience that such surfaces are only likely to be found indoors or
in locations where you're more likely to be walking than riding. A
car's tread wouldn't prevent a slip on such a surface, so a bike's
tread isn't likely to help either. As such, the only remaining reason
to favor a siped or treaded tire over a fully slick one is the fact
that you won't be caught by surprise when it wears out; the
disappearing sipes or tread make it really obvious without even having
to pay close attention. I would not consider minor siping or
patterning to be a drawback that disqualified a tire that was being
bought for commuter use, since the sipes or patternings most likely
would not reduce the tire's useful life by a tremendous amount.



--
My email address is antispammed;
pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.

[Pete Biggs]

Joe Samangitak wrote:
> - Lastly, I read expert testimonials that said slick tires are best
> for pavement riding, cornering, wet driving, traction and have less
> rolling resistance, basically because more rubber contacts the road. I
> was looking to buy the Michelin Transworld City, but its not a pure
> bald slick, it has fairly deep recesses, presumably to siphon off
> water (which I read isn't necessary for bike tires, and that this
> system doesn't work better than slicks). So my question is, would I be
> better off driving in my city with a pure bald slick, such as the
> Avocet Road 20, instead of the Michelin Transworld City?

Possibly but it doesn't mean siped tyres should be avoided, because they
may happen to be generally excellent tyres still with plenty of grip (more
grip than more heavily treaded tyres on road). There aren't too many
totally slick tyres on the market so it's unwise to limit yourself just to
them.

> Or is it even
> better to use DIFFERENT TIRES for the front and back?

Front tyre takes less weight and gets an easier life so it can be
different - different width, different tread, certainly different
pressure. Grip is more of an important factor for front tyre as well.

> Any commonly
> known disadvantages to going with pure bald untreaded slicks on
> pavement, such as premature tire wear, as compared against tires with
> a tread?

Treaded tyres tend to have a deeper layer of rubber so are more puncture
resistant and last longer. If this is a major concern, you could use a
tyre like this at the rear with a lighter, slicker tyre on the front.

~PB

[Dan Daniel]

On 2 Aug 2003 19:19:02 -0700, (Joe Samangitak)
wrote:

>I have 700 x 35 tires on my hybrid bike, and I've recently learned
>that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
>Question is, do I want to? I ride exclusively on pavement in a city,
>so I'd like to maximize tire efficiency for this type of driving.
>
>- First of all, will it work to put different width tires on my
>hybrid/city bike, or is there an issue with narrower widths coming off
>the rim, etc.?
>

Yes, you can put thinner width tires on.

>- Secondly, is there an advantage to using a different tire size if I
>can, or should I assume the original 700 x 35 tire size was already
>designed ideally for city driving?
>
The 35mm was chosen for its aesthetic appeal to the target market for
the bicycle. I'd imagine that most hybrid buyers will put more value
on comfort and the feeling of safety a bigger tire gives than on speed
and efficiency.

There are advantages and disadvantages to narrower tires.

Since they are smaller and often have less rubber than wider tires,
they weigh less and are easier to accelerate. My city riding has a lot
of stops and slowdowns, so it makes a difference for me.

A smaller contact patch means less friction, so they are faster, but
my gut says that this is actually a relatively small difference.

Higher pressure, so less time and energy spent over bumps, etc..
moving the tire itself rather than the whole bike.

Higher pressure and thinner rubber can mean more flats. And more road
bumps transmitted into your body rather than absorbed by the tire.

Road cracks and potholes become much more important. Something that I
can ignore on wide tires can catch a skinny tire and send me down if I
don't pay attention.

For me, different tires and bikes lead to different riding experiences
in a city. A narrow tire requires more attention to the road, I seem
to go faster and so have to pay more attention to traffic, and going
faster can be both stressful and fun. A fatter tire lets me be more
relaxed about the road condition, is less jarring, and lets me jump
curbs and do other things that I wouldn't try on narrow tires.

That's the trade-off I see- speed, precision, and the need to maintain
focus on the road versus comfort, slop, and the ability to not be too
concerned with the road. Each of us finds our own balance point.

I would suggest finding a 28mm tire that is lighter than your present
one and trying it out. Maybe your bike shop has a bike similar to
yours with tires this size, and you can run it around the block to see
how it feels?

Don't forget how important tire pressure is, also. The same tire can
take on very different characteristics at different pressures. I have
some Continental Travel Contacts on a mountain bike, which are 1.75
inches wide. I can use than at 45 lbs or at 80 lbs, and it is close to
changing tires when I change the pressure. If you are running your
present tires at the lower end of their pressure range, go to the top
end to get a taste of some of the changes skinnier tires will make.
Even five or ten pounds can make a huge difference in how a tire
rides.

>- Lastly, I read expert testimonials that said slick tires are best
>for pavement riding, cornering, wet driving, traction and have less
>rolling resistance, basically because more rubber contacts the road. I
>was looking to buy the Michelin Transworld City, but its not a pure
>bald slick, it has fairly deep recesses, presumably to siphon off
>water (which I read isn't necessary for bike tires, and that this
>system doesn't work better than slicks). So my question is, would I be
>better off driving in my city with a pure bald slick, such as the
>Avocet Road 20, instead of the Michelin Transworld City? Or is it even
>better to use DIFFERENT TIRES for the front and back? Any commonly
>known disadvantages to going with pure bald untreaded slicks on
>pavement, such as premature tire wear, as compared against tires with
>a tread?

20mm tires in a city seems extreme. I ride 23mm on one bike and I
think that the next set will be 25mm. 23 just requires more attention
and care than I feel like giving all the time. Then again, I've ridden
23mms in a city for years and keep buying them. 32mm on another bike
was just a bit too heavy and wide for my needs and taste.

Tire life depends on the thickness and quality of the rubber. Tread
per se has nothing to do with it. No tread pattern or a minimal
siping is what I look for. About all you gain from heavy treads is a
funny road buzz and energy going into moving the tire knobs around
rather than moving you forward. But as someone already said, marketing
drives a lot of the tire design issues, so I wouldn't let minimal
treads stop you from buying a tire outright. City riding is not about
the absolute highest level of efficiency. What is very critical to a
racer is one small factor among many for non-competetive city riding.

[Joe Samangitak]

"A Muzi" > wrote in message >...

> Yes you can switch widths within broad limits ( A 700-47 will probably not
> clear your frame and a 700-20 won't last a day on a wide rim). On most fat
> 700 rims a 32 through 38 are fine. I do not know your rim model so I can't
> say what the limits are.

32-38 sounds reasonable, I'm not sure its a good idea to push it to
extremes, beyond the original design of 700 x 35.

> If your dealer has a clue s/he should be able to
> make a recomendation. Do you want faster? Tougher? A softer ride? The
> ability to better corner agressively?

I don't care to win any races, but less effort would be nice, because
I'm extremely lazy. Hence the reason I am looking at baldies; less
rolling resistance. The streets the bike will ride on are all paved,
but there are plenty of cracks to deal with, and often have to jump on
or off the sidewalk, so there are bumps to deal with. I don't know
that I need to corner "aggressively", because I'm not an aggresive
rider; but I want to corner -safely-, particularly in wet conditions,
if I get caught in the rain. I do not ever want to crash. It would
help if I simply knew, in general, what the advantages and
disadvantages are between "skinnier" and "fatter" tires.

> Tread is completely irrelevant on a paved surface.
>
> The Michelin Transworld City is a great urban tire, I like them lots more
> than the cheap knobby o.e.m. tires on $300~$500 bikes. They're long-wearing
> and smoother riding.

My original tires were Japanese-made Panaracers (Ridge Line 2). So
they weren't OEM's and they didn't seem cheap, but I'm replacing them
because I recently learned they have no business being on a bike that
is designed to ride exclusively on pavement.

> That said, the siping is only there to pander to
> customers' misunderstandings of tires and treads. Smooth would have been
> better and Michelin knows it.

You see, THIS is why I am thinking of exchanging the Michelin
Transworld City tire that I bought. Because I only learned afterward
that tread siping only caters to ignorant cyclists; which I do not
want to be! If I can get a better tire for no more than the price of
the Transworld City, then I want to get the choice right now.

> Other popular tires for your bike are Inoue-IRC's Metro 700-38 on the fat
> side, Panaracer Pasela 700-35 for a medium tire and the wonderfully fast
> IRC Tandem 30 if you are not a heavy or abusive rider and your route is free
> of pavement anomalies. Keep the pressure up always but especially if you go
> to a skinnier tire.

The Pasela is not a bald slick, it has some light treads (while the
Transworld City also has a tread, its quite a different surface than
the Pasela). So I'm wondering between the two, which is better and
why? (As for the IRC Metro, although its nearly treadless with little
siping, I only see it listed in mountain bike tire sizes (26 x ?), and
it looks like it will be near impossible for me to get at my local
dealers).

[mark freedman]

(Joe Samangitak) wrote in message >...

www.sheldonbrown.com has an article on tire / rim sizes.
There are limits to how narrow or wide on can safely go on
a given rim. Also a pointer to the faq, since tire width
and tread have been discussed often (google groups lets you
read old articles posted here).


>
> so I'd like to maximize tire efficiency for this type of driving.
>
Define efficiency ?

I like 700*28 or 700*32 tires with a puncture-resistant belt
and some tread. I don't always see obstacles in time to avoid them,
and dropping a 700*23 tire into a sewer grate ain't fun :-(


>narrower widths coming off > the rim, etc.?

See the table at sheldonbrown.

>
> can, or should I assume the original 700 x 35 tire size was already

Probably fine in terms of comfort and resistance
to road hazards. Also, marked widths are not consistent,
so a PanaRacer 35 may be narrower than a Kenda 35. And
tire pressure matters - cheaper tires may have lower
maximum pressures.

>
> - Lastly, I read expert testimonials that said slick tires are best

My limited experience has been that I get more punctures
as the tread vanishes (around 5000 km, I usually replace at
7000 km). So a glass shard which I ride over with impunity on
a new tire (tread) leaves me flat once the tread has worn away.

There's probably a trade-off. When I was using COntinental
Super SPort (slight tread, no puncture-resistant belt) I
was getting 5 or 6 flats / week. People smash bottles on the
bike paths. People sprinkle nails on the bike paths. And there's
always accident debris on the roads - the "bike lanes" are such
a convenient place to sweep broken glass and metal parts.

hth

[E & V Willson]

Joe,

I recommend that you measure the width of your rims, and then go to
Sheldon Brown's website to see what range of tire widths will fit
properly.

http://www.sheldonbrown.com/tire_sizing.html#width

IIRC the number in the tire size (like your 35mm) is really the tire
height, not the width, although the width is just about the same as the
height.

The effort it takes to propel a bike is dependent on the tire rolling
resistance. To a first approximation, rolling resistance is dependent on
the tire pressure and width. Generally speaking the narrower the tire the
higher the pressure and the lower the rolling resistance. Depending on
your rim dimensions you may be able to use tires as narrow as 25mm. For my
road work I use 700x23 and 700x20's, on narrow rims.

To further lower the effort required to propel the bike you can get light
weight tires and tubes. This will lower the rotating mass and make it
easier to accelerate the bike. The lower limit for clincher type tires is
about 200 grams, some run up to 400 grams.

Tires narrower than 25 mm are sometimes difficult to mount, and require
pressures of 90 to 120 psi. You may need a new pump. The narrower the
tire, the higher the pressure, and the rougher the ride. I do not find my
20 and 23mm tires objectionable from a ride point of view, but my roads
are not bumpy.

As for tread, at the risk of being flamed, it has been my experience that
it really doesn't matter that much for road work. Just make sure that the
tread is reasonably smooth, and does not have knobs. Buy a "road tire" and
you should be OK.

HTH,
Ernie

Joe Samangitak wrote:

> I have 700 x 35 tires on my hybrid bike, and I've recently learned
> that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
> Question is, do I want to? I ride exclusively on pavement in a city,
> so I'd like to maximize tire efficiency for this type of driving.
>
> - First of all, will it work to put different width tires on my
> hybrid/city bike, or is there an issue with narrower widths coming off
> the rim, etc.?
>
> - Secondly, is there an advantage to using a different tire size if I
> can, or should I assume the original 700 x 35 tire size was already
> designed ideally for city driving?
>
> - Lastly, I read expert testimonials that said slick tires are best
> for pavement riding, cornering, wet driving, traction and have less
> rolling resistance, basically because more rubber contacts the road. I
> was looking to buy the Michelin Transworld City, but its not a pure
> bald slick, it has fairly deep recesses, presumably to siphon off
> water (which I read isn't necessary for bike tires, and that this
> system doesn't work better than slicks). So my question is, would I be
> better off driving in my city with a pure bald slick, such as the
> Avocet Road 20, instead of the Michelin Transworld City? Or is it even
> better to use DIFFERENT TIRES for the front and back? Any commonly
> known disadvantages to going with pure bald untreaded slicks on
> pavement, such as premature tire wear, as compared against tires with
> a tread?

[Werehatrack]

On Sun, 3 Aug 2003 06:57:52 +0100, "Gearóid Ó Laoi, Garry Lee"
> may have said:

> While there are some who will state that
>> a treaded tire will not slip as easily on a damp polished concrete
>> surface (which is inherently treacherous territory),
>
>There are some who say that the world is flat too, and that George Bush is
>intelligent, and that he fairly won the American Presidential election, and
>that Elvis lives and that Saddam Hussein was a gentle soul and that the
>body's energy centres are entwined around the nostrils and that
>Shakespeare's plays were not written by him but by another man of the same
>name...

And that NASA just used special effects and crummy video to simulate
the whole moon lnding, and that they have proof that there was or
wasn't a vast global conspiracy responsible for the assassination of
JFK. Fortunately, I'm not any of them, for any of the categories
listed. (Well, OK, I have to admit that sometimes my sneezing might
be considered evidence for the energy center thing, but I don't buy
any of that mystical "energy" stuff myself; I pronounce "New age" as a
single word with a very short "a". Rhymes with somthing smelly. You
get the idea.) (BTW, my pagan friends are largely of the same opinion
on that topic. Go figure.)

Meanwhile, my approach to riding on wet streets is "unless
unavoidable, just don't." It's mostly a fender thing, though. I hate
having to clean the mud stripe out of my shirt.

--
My email address is antispammed;
pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.

[Joe Samangitak]

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).

[Dan Daniel]

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/generator/www/de/en/continental/bicycle/themes/tires/city/travelcontact/travelcontact_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.

[Rick Onanian]

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

[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

[GRL]

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
...
> 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

[Pete]

"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/Articles/RollingResistance.pdf
http://www.legslarry.beerdrinkers.co.uk/tech/GS.htm

Pete

[Rick Onanian]

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

[Pete]

"Rick Onanian" > wrote in message
...
> 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