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



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Joe Samangitak

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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?
 
"Joe Samangitak" <[email protected]> wrote in message
news:[email protected]...
> 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
 
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
 
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...
 
"A Muzi" <[email protected]> wrote in message news:<[email protected]>...

> 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).
 
[email protected] (Joe Samangitak) wrote in message
news:<[email protected]>...

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
 
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?
 
On Sun, 3 Aug 2003 06:57:52 +0100, "Gearóid Ó Laoi, Garry Lee" <[email protected]> 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.
 
On 3 Aug 2003 00:53:33 -0700, [email protected] (Joe Samangitak) may have said:

> 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.

Skinnier tires = better grip in the really wet on smooth surfaces, fatter = better grip everywhere
else; at least, that's how it works for me.

>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.

Catering to ignorance in order to get a *good* product accepted, and to ensure sufficient sales to
make a competitive price possible, is a time-honored tradition. Refusing to use such a product
merely because it has a market-driven feature is, to be blunt, short-sighted when that feature will
do no harm, as is the case for the sipes on the Michelin. (If anyone criticizes the choice, then
they are the ones being ignorant, since it *is* a good tire.)

Remember: the wise person puts image second to function unless image *is* the function.

Bright yellow tires, however, are just plain silly.

--
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.
 
I have two hybrids. On the newer one, a Waterford Adventure Cycle touring frame with S and S
couplings and straight handle bars, which I use for touring, I use Avocet Cross K 700x38, but I am
going to go to 700x35, both with 85-90 psi. For touring I like the comfort, and also the better
ability to handle a wide variety of road surfaces, including broken asphalt, dirt and gravel.

On the older one, a Klein Adept, which I have lightened as much as possible, I am using Avocet Fast
Grip 700x28 -- I have also tried the Cross K's 700x32, both 105 psi. These are more efficient -- I
can have an easy cruise at say 17-18 mph vs 14-15 mph. The books on rolling resistance state that it
comes from the deformation of the tire/wheel and the road surface. Thus steel on steel, as with
railroads, produces the least rolling resistance. Likewise, a high pressure tire on a hard surface
will produce less rolling resistance. From what I read, the tire pressure is more important than the
width, although the narrower tire probably produces less wind resistance, and has less weight at the
perimeter which requires less torque for acceleration. My technical comments are based on my
recollection of the discussion in "Bicycling Science", Second Edition, by Whitt and Wilson,
published by The MIT Press, which I read a couple of years ago.

At this point I can't say that I notice much diffence in the comfort riding zone with the narrower
tires. The wider tires are better on poor road surfaces, and probably safer. Also, while touring --
in Central Europe for example, I have been on some pretty wild road surfaces, on which I appreciated
the wider softer tires.

The Cross K's by the way, roll very well on the paved road, and I can coast downhill as fast as most
bikes with smoother tires. The inverted zig zag tread keeps th tire in constant contact with the
pavement. However, knobbies take a bit toll on efficiency -- my guess based on my personal
performance experienc (somewhat subjective to be sure) about 25%.

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?

--
Cheers! OliverS When replying personally, remove "_removespam_"

"When I see an adult on a bicycle, I do not despair for the future of the human race." HG Wells
 
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).
 
On 3 Aug 2003 13:44:45 -0700, [email protected] (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.
 
On Sat, 2 Aug 2003 21:34:08 -0500, A Muzi <[email protected]> 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
 
By the magic of Webby Science, there are some figures here:

http://www.legslarry.beerdrinkers.co.uk/tech/JL.htm

and here:

http://www.legslarry.beerdrinkers.co.uk/tech/GS.htm

and here:

http://www.ice.hpv.co.uk/495000_Soapbox_Tyres_TRS.pdf

The ICE and Greenspeed ones are mostly for small tyres, though.

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================
 
On Sun, 03 Aug 2003 17:09:50 GMT, Werehatrack <[email protected]> wrote:
> Bright yellow tires, however, are just plain silly.

My bike is bright yellow... I could conceivably buy some yellow tires someday, if I'm confident that
they are good tires.

Recently, I bought a couple clearance tires from Nashbar, and I think one has a blue stripe and the
other has a red stripe...I think they'll look okay, but if they don't, at least I think they'll be
otherwise good tires, and they sure were inexpensive!
--
Rick Onanian
 
On Sun, 03 Aug 2003 17:50:48 GMT, OliverS <[email protected]> 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" <[email protected]> wrote in message
news:eek:[email protected]...
> On Sat, 2 Aug 2003 21:34:08 -0500, A Muzi <[email protected]> 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" <[email protected]> wrote in message news:[email protected]...
> 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
 
On Thu, 7 Aug 2003 20:08:29 -0400, GRL <[email protected]> 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
 
On Fri, 08 Aug 2003 01:08:40 GMT, Pete <[email protected]> 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? :)

> Pete
--
Rick Onanian
 
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