20 vs 23 mm tires

Francesco Devittori wrote:
>
> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco

No.

Lou
--

"Francesco Devittori" wrote:
> Is there any concrete advantage of the 20 mm tires against 23 ones?

They are a bit lighter and might have slightly lower rolling resistance when pumped up hard as a
rock. But in general they are not a good choice. They are prone to pinch flats, give a harsh ride,
and have poor traction. They should only be considered by very lightweight riders.

Many riders would be better off with 700 x 25 tires.

Art Harris

Francesco-<< Is there any concrete advantage of the 20 mm tires against 23 ones? >><BR><BR>

Nope, best combo of what you want a tire to do is found in 23 or 25c tires.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

"Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in message
news:[email protected]...
> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco
>
>
Unless you're TT-ing, 20s are usually NOT the best choice. More prone to pinch flats, you have to
pump them up harder to ride them safely, etc.

Mike

In article <[email protected]>, "Francesco Devittori"
<francesco.devittori-[-AT-]-epfl.ch> wrote:

> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco

You're going to hear a lot of naysayers in this ng, but I have run both 20 and 23 mm tires this year
on my race/commute Pinarello, and there are two major advantages to 20 mm tires:

1) I can take off the tire without opening the quick release

2) I don't have enough clearance to mount fenders with the 23 mm tires.

Seriously, beyond that, I haven't noticed any effects. Minor equipment changes don't usually make
much of an impression on me, but the 20 mm tires didn't seem to make the ride notably harsher, but
neither did I get any slower on the 23s. I have managed 1 flat with each set of tires, so that seems
to be a wash as well.

There might be a miniscule aero advantage to the 20s, but only with the right rim combo, and even
then it's dwarfed by stuff like using aero bars and getting your position right. It shouldn't make
enough difference to bother outside of TTs.

Share & Enjoy,
--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

"Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in message
news:[email protected]...
> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco
>

I concur with the previous posts. I'm quite light, 130 lbs. and have ridden 20's for many years.
However, I ride on fairly smooth roads most of the time. When I moved to Western Colorado for 18
months, I quickly took the local riders' advice and switched to 23's at about 100 lbs pressure. Most
of the heavier riders used 25's. These were all fast recreational riders and racers. They made the
rough chip-sealed roads feel much smoother and they didn't pinch flat nearly as easily. They also
gave better traction on the fast mountain downhills. As soon as I wear out my existing stock of
20's, I'm only buying 23's. Get big tires and ride'm at lower pressure for much more comfort. The
slightly higher air resistance and very slightly more rolling resistance is really in the noise
unless you're on your TT bike going for every second. Oh yes, get good quality 23's with fairly high
thread count so they are reasonably supple. Don't get some real cheapie's with rubber like a rock.

Just my $.02 worth.

Vol

"Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in message
news:[email protected]...
> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco
>
>

It feels like you are riding on concrete tyres with 20mm. I have been riding 20mm recently as I got
some cheap and have just gone back to 23mm and I cant believe how much more comfortable they are.

Stan Cox

"Mike S." <mikeshaw2@coxDOTnet> wrote in message news:4_L4b.36116$cj1.34080@fed1read06...
>
> "Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in
message
> news:[email protected]...
> > Is there any concrete advantage of the 20 mm tires against 23 ones?
> >
> > Francesco
> >
> >
> Unless you're TT-ing, 20s are usually NOT the best choice. More prone to pinch flats, you have to
> pump them up harder to ride them safely, etc.
>

Not to mention parallel-to-direction-of-travel cracks filled with rubber crack filler. Whoa!

Doesn't Jobst's tire rolling resistance data show that wider tires (all else being equal) like 25's
have less rolling resistance than narrower tires?

--
Robin Hubert <[email protected]

"Stan Cox" <[email protected]> wrote in message
news:[email protected]...
>
> "Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in
message
> news:[email protected]...
> > Is there any concrete advantage of the 20 mm tires against 23 ones?
> >
> > Francesco
> >
> >
>
> It feels like you are riding on concrete tyres with 20mm. I have been
riding
> 20mm recently as I got some cheap and have just gone back to 23mm and I
cant
> believe how much more comfortable they are.
>

Try some 25's and you'll think you're riding in luxury.

--
Robin Hubert <[email protected]

At my Senior Citizen age, I like a 23 in front and a 25 on rear of my 'racing' bike.

And on my touring bike its a 25 up front and a 28 on the rear.

Moral to this story, is there is no comfortable saddle, but the above tire combination sure helps
what sits on the saddle and does not increase drag that much.

Tom

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"Robin Hubert" wrote:

> Not to mention parallel-to-direction-of-travel cracks filled with rubber crack filler. Whoa!

Good point.

> Doesn't Jobst's tire rolling resistance data show that wider tires (all else being equal) like
> 25's have less rolling resistance than narrower tires?

Yes, but all else is usually not equal. You wouldn't run 20's at 100 psi.

Art "likes 25's" Harris

20mm equals less tire in contact with the road which in turn equals more pressure at the point of
contact with the road equaling a higher rolling resistance. 23 or 25mm give you more tread contact
with the road and less pressure at the the point of contact with the road. Of course there is
probably a break point where more tire surface will start to negate the adavantage of spreading the
riders wieght over the larger area. This break point would also vary with the wind resistance that
the tire would generate.

Unless you want to bankroll a study, I surmise that 23-25mm tires are better performers than 20mm
tires. I train and race on conti 25s.

Good post.

"Francesco Devittori" <francesco.devittori-[-AT-]-epfl.ch> wrote in message
news:[email protected]...
> Is there any concrete advantage of the 20 mm tires against 23 ones?
>
> Francesco

"Matt" <[email protected]> wrote in message news:Ya36b.365228$o%2.164955@sccrnsc02...
> 20mm equals less tire in contact with the road which in turn equals more pressure at the point of
> contact with the road equaling a higher rolling resistance.

I thought this would be the other way around...that a narrower tire would have lower rolling
resistance. At least that's true with car tires...

I'm also not sure that there's a measurable difference in contact patch between a 20mm and a 25mm
tire in steady state riding.

>23 or 25mm give you more tread contact with the road and less pressure at the the point of contact
>with the road. Of course there is probably a break point where more tire surface will start to
>negate the adavantage of spreading the riders wieght over the larger area. This
break
> point would also vary with the wind resistance that the tire would
generate.
>
> Unless you want to bankroll a study, I surmise that 23-25mm tires are better performers than 20mm
> tires. I train and race on conti 25s.

I just bought a set of Conti 4 season tires in a 25 mm size for training, but I do intend to
continue my racing on 23mm tires. Never found a narrower clincher that I liked *and* was relatively
durable. I get a couple thousand miles out of a set of Vittoria Open Corsa CX tires. (I'm 150 pounds
and I'm generally pretty easy on wheels/tires).

Lee

"Matt" <[email protected]> wrote:

> 20mm equals less tire in contact with the road which in turn equals more pressure at the point of
> contact with the road equaling a higher rolling resistance. 23 or 25mm give you more tread contact
> with the road and less pressure at the the point of contact with the road.

Matt may be wrong here, and may be right.

It depends on the tire's air pressure. A 23 and a 25 will have exactly the same contact area if
their pressures are the same. You know, pounds per square inch, and the pounds of the bike/rider are
the same in both cases.

--
Ted Bennett Portland OR

Ted Bennett writes:

>> 20mm equals less tire in contact with the road which in turn equals more pressure at the point of
>> contact with the road equaling a higher rolling resistance. 23 or 25mm give you more tread
>> contact with the road and less pressure at the the point of contact with the road.

> Matt may be wrong here, and may be right.

> It depends on the tire's air pressure. A 23 and a 25 will have exactly the same contact area if
> their pressures are the same. You know, pounds per square inch, and the pounds of the bike/rider
> are the same in both cases.

Tire pressure is not something that can be picked arbitrarily because its upper safe limit is
governed by the clinch of the tire bead and that is independent of tire cross section. To visualize
this draw a free body diagram showing the cross section of the tire and rim interface. Note that at
a plane across the rim at the bead sees the same separation pressure (pushing down on the rim and up
on the tire) regardless of the tire attached to the rim.

The only reason why smaller tires sometimes have less rolling resistance it that they use thinner
tubes, casings, and tread, all of which absorb energy when flexing. Rolling resistance is not caused
by scrubbing on the road but rather flexing of the elastomers in the tire. That includes tube and
tread rubber as well as inter-ply bonding material.

Aside from that, fatter slicks corner better than thin ones.

Jobst Brandt [email protected]