Bikes: 700/23 vs 700/25 tires?

[jeffreybike]

Is there any real difference between 23mm and 25mm tires as far as
speed. Will 2mm make you that slower or faster?
thanks, Jeff

[Chalo]

>
> Is there any real difference between 23mm and 25mm tires as far as
> speed. Will 2mm make you that slower or faster?

There is no significant difference in speed between those two sizes of
tire. Too narrow a tire will slow you down quite a lot when you get a
pinch flat and have to stop and repair it.

Instrumented tests have shown that for tires of equal construction,
wider tires have slightly less rolling resistance at the same
pressure. Narrower tires have slightly less aerodynamic drag. While
these factors mostly offset each other, all other benefits (rim
protection, ride quality, wear life, pinch flat resistance, traction)
give the advantage to the wider tire.

Sport road bikes generally work best with the widest tire that will
fit under the brakes and between the chainstays with adequate
clearance. This is often a 28mm tire.

Chalo

[Pete Biggs]

> jeffreybike wrote:
>>
>> Is there any real difference between 23mm and 25mm tires as far as
>> speed. Will 2mm make you that slower or faster?
>
> There is no significant difference in speed between those two sizes of
> tire. Too narrow a tire will slow you down quite a lot when you get a
> pinch flat and have to stop and repair it.

The rider will never get a pinch flat if it can be inflated highly enough to
support his weight when the tyre is slammed into potholes, etc.

> Instrumented tests have shown that for tires of equal construction,
> wider tires have slightly less rolling resistance at the same
> pressure.

But wider tyres should not be inflated so highly to provide the same
suspension and traction, so then they are slower on the smoothest surfaces,
though faster on bumpy surfaces.

> Narrower tires have slightly less aerodynamic drag.

And less weight.

> While
> these factors mostly offset each other, all other benefits (rim
> protection, ride quality, wear life, pinch flat resistance, traction)
> give the advantage to the wider tire.
>
> Sport road bikes generally work best with the widest tire that will
> fit under the brakes and between the chainstays with adequate
> clearance. This is often a 28mm tire.

Often 25mm too, sometimes only 23mm.

~PB

[Peter Cole]

russellseaton1**********m wrote:
> On Jan 28, 9:27 pm, jeffreybike <jeffreyb...**********m> wrote:
>> Is there any real difference between 23mm and 25mm tires as far as
>> speed. Will 2mm make you that slower or faster?
>> thanks, Jeff
>
> I used to use 23 mm tires exclusively. Fashion I suppose. I now use
> mostly 25mm tires. I can't tell any difference in speed, comfort,
> traction, flat rate, or anything else.

I went through the same process, then went on to 28mm, 32mm, and now
35mm on one bike. Fatter tires might be slightly slower, but it's small
enough to not be obvious. The difference in comfort is pretty obvious.

[Chalo]

>
> John Forrest Tomlinson wrote:
> >
> >Chalo wrote:
> >>
> >>Instrumented tests have shown that for tires of
> >>equal construction, wider tires have slightly less
> >>rolling resistance at the same pressure. *Narrower
> >>tires have slightly less aerodynamic drag. *While
> >>these factors mostly offset each other, all other
> >>benefits (rim protection, ride quality, wear life,
> >>pinch flat resistance, traction)give the advantage
> >> to the wider tire.
> >
> >This depends on how much one weighs and what sort
> > of roads the person is riding on.

In my observation, the road surface has a much bigger role in
dictating the appropriate minimum tire size. It is true that fatter
tires usually have a higher weight rating, and when the rider's weight
goes high enough, this becomes a consideration.

> And also the speeds at which the person is riding.

The faster you ride, the more you need in terms of rim protection,
shock absorption, wear resistance, pinch flat resistance, and
traction. So the faster you go, the more you can benefit from a wider
tire.

Chalo

[Carl Sundquist]

> John Forrest Tomlinson wrote:
>> John Forrest Tomlinson wrote:
>>> Chalo wrote:
>>>> Instrumented tests have shown that for tires of
>>>> equal construction, wider tires have slightly less
>>>> rolling resistance at the same pressure. Narrower
>>>> tires have slightly less aerodynamic drag. While
>>>> these factors mostly offset each other, all other
>>>> benefits (rim protection, ride quality, wear life,
>>>> pinch flat resistance, traction)give the advantage
>>>> to the wider tire.
>>> This depends on how much one weighs and what sort
>>> of roads the person is riding on.
>
> In my observation, the road surface has a much bigger role in
> dictating the appropriate minimum tire size. It is true that fatter
> tires usually have a higher weight rating, and when the rider's weight
> goes high enough, this becomes a consideration.

Yes, we know that you have special considerations where weight is a
concern. But in that regard, you are an outlier. We all have personal
agendas though. I, for one, tend to think generally from sporting angles
rather than utilitarian, though I do love the utilitarian aspect of my
bikes.

>
>> And also the speeds at which the person is riding.
>
> The faster you ride, the more you need in terms of rim protection,
> shock absorption, wear resistance, pinch flat resistance, and
> traction. So the faster you go, the more you can benefit from a wider
> tire.
>
> Chalo

[Nick L Plate]

Wired on tyres, 25mm+ on rear perhaps 22+on front, anything less is
painful if you're 3+ hours in the saddle. Rider fatigue caused by
constant road shock will slow you more over a long ride, than a less
than optimum aero tyre/rim combination.
If you 'need' narrow tyres, use tubs, a 23mm tub is more comfortable
and grips better in the corners(than 25mm wired) due to a longer
contact patch at an appropriate riding pressure. Steering response
will also become less jittery with a short trail set up. Confidence
in cornering over rough surfaces improves reducing rider tension and
improves speed through corners.

[Keiron]

>>
>> Is there any real difference between 23mm and 25mm tires as far as
>> speed. Will 2mm make you that slower or faster?
>
> There is no significant difference in speed between those two sizes of
> tire. Too narrow a tire will slow you down quite a lot when you get a
> pinch flat and have to stop and repair it.
>
> Instrumented tests have shown that for tires of equal construction,
> wider tires have slightly less rolling resistance at the same pressure. [/color]
--snip--
According to Sheldon this is rather moot as generally speaking wider tyres
at the same pressure are over inflated or narrow tyres at a same pressure
to wider ones will be under inflated (and so not being used optimality
presumably). As I understand it anyway. Might not be that relevant with
the 2mm difference but just throwing out there.

Having said that: in reality little difference in speed I suppose.

[Chalo]

>
> Chalo wrote:
> >
> > JFT wrote:
> >>
> >> But why dod you need more for rim protection when going fast? *Or
> >> shock absorbtion? *Or wear resistance?
>
> >Because the energy contained in bumps goes up as the square of the
> >speed. *It's four times easier to pinch flat or flat spot a rim at
> >30mph than at 15mph.
>
> Bumps have only a horizontal component? Interesting.

Do you think the speed of travel has nothing to do with the vertical
rate of acceleration of a bump?

[Nick L Plate]

On 30 Jan, 19:49, "Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote:
>
> I really think you're underestimating the effort people go to to work such
> things out. There are people out there spending a lot of time with wind
> tunnels etc trying to squeeze seconds for races. It's more pertinent for
> stuff against the clock (TTs, pursuits, etc), but that's quite strong over
> here.
>
> Sure, the superstitious mentality you're describing exists, but at the very
> top level it is backed up by actual research.

No matter what research is done, it really is dow to the individual
rider, who may perform better on a wider tyre, wether perceived or
actual. I suspect the return to wider tyres has been due to the
availability of rims. Deep stiff rims mean the tyre has to work more
in minimising shock and maintaining grip. Late 80's - Only the
incorrect labeling of tyres by Specialized did I use tyres less than
23mm(actual 21mm-label 25) good tyre but still overtly narrow which
encouraged slipout. High pressure to avoid pinch flats means a
shorter contact patch. I had no choice in pressure, they had to be at
120psi, this was also a bit juddery at times and felt inefficient over
rough ground.