Tire Width vs. Performance

Ed Kirstein' ekirstein_atcatskill.net may have said:

I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice if
I switched to about a 28 tire? Will pedaling be noticeably easier. I'm not riding on too many rough
bike paths, mostly paved roads and besides I have front and seat post suspension. Thanks,

The main thing you'll notice is that the 28 tire will transmit more of the road shock though to the
bike. The suspension will absorb a lot of it. One word of warning, though: Make sure your rims are
narrow enough to work well with the 28. A rim wider than 19mm is a less than optimal choice for a
28, although it's physically possible to mount the tire and run it. You may experience an increase
in pinch flats if you encounter many potholes or other sharp bumps. Also, because the tire will have
less ability to absorb bumps, the rim is at greater risk of damage on hard impacts. This is
exascerbated by larger tire/rim size mismatch in the direction that you're going. As for pedalling
effort and such, if you're into road performance, you might notice a slight reduction in rolling
resistance. Depending on the relative characteristics of the two tires, it may be hard to tell the
difference, or easily perceptible, or anywhere in between.

There's a table of the recommended tire size ranges for each rim width near the botom of this page:

sheldonbrown.comtire sizing.htmlOpen ↗

For a 19mm rim, 28 is at the narrow end of the acceptable range, and 44 is at the other extreme. If
your bike came with 42s, it is likely that it uses a wider rim than a 19.

--
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.

For what you are doing (paved road, etc), I would not change your tires. Tire width isn't
necessarily a performance hit too much unless the tread is knobby. Tires such as Armadillo (where
they have bumps and lines) go a lot slower. Their benefit is excellent traction (when turning
sideways close to ground, and running through rough terrain) that would otherwise cause a smooth
road bike tire to slip and cause you to fall.

But this is all stuff you don't need due to the way you are riding. There are so many benefits of
road bike (racing-style) tires over all terrain tires. They are much faster, have less wind
resistance, and take less air to fill (though they do not retain the pressure as long as all
terrain tires
do).

I have both road bike tires and my stock Crossroads EX tires (all terrain). For commutes, either is
fine. For riding fast, with groups, or training, the racing tires are best. For certain trails the
all terrain are best. I suggest buying a pair (make sure they match your bike well by putting them
on at the store [if allowed] and check your brake clearance).

--
-Greg P.

dp. Butcher: "The patient's screaming disturbing me, performed removal of vocal chords."

"Ed Kirstein" <ekirstein_atcatskill.net> wrote in message "]news:[email hidden]...
| I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice if
| I switched to about a 28 tire? Will pedaling
be
| noticeably easier. I'm not riding on too many rough bike paths, mostly paved roads and besides I
| have front and seat post suspension. Thanks,
|
| Ed
|
|

"Greg P." <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

For what you are doing (paved road, etc), I would not change your tires. Tire width isn't
necessarily a performance hit too much unless the tread

is

Quoted message said:

knobby. <Snip>

Quoted message said:

But this is all stuff you don't need due to the way you are riding. There are so many benefits of
road bike (racing-style) tires over all terrain tires. They are much faster, have less wind
resistance, and take less air

to

Quoted message said:

fill (though they do not retain the pressure as long as all terrain tires
do).

<Snip>

-Greg P.

Quoted message said:

I am completely confused by your post. In the first paragraph you seem pretty clear that you don't
think that the OP would benefit by changing his tires. In the second paragraph you give many
benefits to switching to road tires. Am I missing something?

In article <[email hidden]>, ekirstein_atcatskill.net says...

Quoted message said:

I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice if
I switched to about a 28 tire? Will pedaling be noticeably easier. I'm not riding on too many rough
bike paths, mostly paved roads and besides I have front and seat post suspension. Thanks,

If your 42's are knobby and the 28's are slicks, you will notice a difference in the way of less
rolling resistance.
------------
Alex

"]news:[email hidden]...
| I am completely confused by your post. In the first paragraph you seem pretty clear that you don't
| think that the OP would benefit by changing
his
| tires. In the second paragraph you give many benefits to switching to
road
| tires. Am I missing something?

No. I was just adding that it would be a good idea to have a pair of all terrain and road tires
for the bike. But a permanent switch is not a good idea, especially for what the poster is
wanting to do.

Actually, the rim the bike came with is an Alex DM18 which is 18mm, double wall. I looked at that
table you mentioned and that's where I came up with the possibility of going down to a 28.

"Werehatrack" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Ed Kirstein' ekirstein_atcatskill.net may have said:

I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice
if I switched to about a 28 tire? Will pedaling

be

Quoted message said:

Quoted message said:

noticeably easier. I'm not riding on too many rough bike paths, mostly paved roads and besides I
have front and seat post suspension. Thanks,

The main thing you'll notice is that the 28 tire will transmit more of the road shock though to
the bike. The suspension will absorb a lot of it. One word of warning, though: Make sure your rims
are narrow enough to work well with the 28. A rim wider than 19mm is a less than optimal choice
for a 28, although it's physically possible to mount the tire and run it. You may experience an
increase in pinch flats if you encounter many potholes or other sharp bumps. Also, because the
tire will have less ability to absorb bumps, the rim is at greater risk of damage on hard impacts.
This is exascerbated by larger tire/rim size mismatch in the direction that you're going. As for
pedalling effort and such, if you're into road performance, you might notice a slight reduction in
rolling resistance. Depending on the relative characteristics of the two tires, it may be hard to
tell the difference, or easily perceptible, or anywhere in between.

There's a table of the recommended tire size ranges for each rim width near the botom of
this page:

sheldonbrown.comtire sizing.htmlOpen ↗

For a 19mm rim, 28 is at the narrow end of the acceptable range, and 44 is at the other extreme.
If your bike came with 42s, it is likely that it uses a wider rim than a 19.

--
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.

The 42's are smooth in the center and only a moderate tread toward the sides. Not a knobby tire
at all. Ed

"Alex Rodriguez" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

In article <[email hidden]>, ekirstein_atcatskill.net says...

Quoted message said:

I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice
if I switched to about a 28 tire? Will pedaling

be

Quoted message said:

Quoted message said:

noticeably easier. I'm not riding on too many rough bike paths, mostly paved roads and besides I
have front and seat post suspension. Thanks,

If your 42's are knobby and the 28's are slicks, you will notice a

difference

Quoted message said:

in the way of less rolling resistance.
------------
Alex

RE/

Quoted message said:

I am riding a Hybrid with 700C x 42 tires. Can anyone tell me how much difference I will notice if
I switched to about a 28 tire? Will pedaling be noticeably easier. I'm not riding on too many rough
bike paths, mostly paved roads and besides I have front and seat post suspension. Thanks

Dunno from the metric sizes, but I switch between 1.25" slicks at 90 psi and either Mutano Raptors
("55/55" on the side wall) at 40-45 psi or Heng Shin SemiSlicks ("53/559"😉 at 60 psi.

I don't notice a huge diff between the to fat tires speedwise.

With the 1.25" tires, there is an enormous diff: 20% minimum, maybe 25-30% - judged by
gear/cadence/speed on a long paved straightaway.

If I have to ride with (i.e. stay with...) somebody on a paved ride, the 1.25" tires can really save
my butt if the other guy has MTB tires.
-----------------------
PeteCresswell

(Pete Cresswell) said:

With the 1.25" tires, there is an enormous diff: 20% minimum, maybe 25-30% - judged by
gear/cadence/speed on a long paved straightaway.

The smaller tires surely have less rolling resistance, but remember, they also make the overall
wheel diameter smaller too. It's not unusual for an MTB wheel with 1.25 slicks to measure 10% less
in diameter than a fat knobby. Unless you recalibrate your cyclocomputer to match, it (and your
cadence) will tell you you are going 10% faster even at the same speed!

I think the remaining 10-15% is a better guess at the best speed improvement tires are
likely to offer.

Chalo Colina

Quoted message said:

Alex Rodriguez said:

If your 42's are knobby and the 28's are slicks, you will notice a difference in the way of less
rolling resistance.

Ed Kirstein' ekirstein_atcatskill.net said:

The 42's are smooth in the center and only a moderate tread toward the sides. Not a knobby
tire at all.

To put it another way, if there is a noticeable thickness to the rubber in the center of the tread,
whether as knobs or as a built-up smooth surface, then a thinner-treaded tire will give less rolling
resistance.

Knobs make things worse, but the thickness of the tread rubber is the most important factor in
rolling resistance.

Chalo Colina

Ed Kirstein' ekirstein_atcatskill.net may have said:

Actually, the rim the bike came with is an Alex DM18 which is 18mm, double wall. I looked at that
table you mentioned and that's where I came up with the possibility of going down to a 28.

28 on an 18 sounds good to me; I guess you've got a potential winner there.

--
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.

Since you're on the road, get some 28mm slicks. It will take much less energy to turn these. Smaller
tires are usually lighter. This is good because less energy is consumed when you are accelerating.
Remember, knobbies must also dig into the wind and are buggers when you want to go fast.

Dave

In article said:

Smaller tires are usually lighter. This is good because less energy is consumed when you are
accelerating.

Uh oh, it's the "rotating mass" argument again. Suffice it to say that rotating mass has a neglible
impact on acceleration, and we'll be done with it.

Interested parties can search google for a google of arguments on rotating mass.
--
terry morse Palo Alto, CA terrymorse.combikeOpen ↗

RE/

Quoted message said:

The smaller tires surely have less rolling resistance, but remember, they also make the overall
wheel diameter smaller too. It's not unusual for an MTB wheel with 1.25 slicks to measure 10% less
in diameter than a fat knobby. Unless you recalibrate your cyclocomputer to match, it (and your
cadence) will tell you you are going 10% faster even at the same speed!

Good catch! And those Mutano Raptors I use increase the diameter even more than most - to the extend
that if I try running v brakes on my hardtail, the tread is just sort of buffing the brake wire.
-----------------------
PeteCresswell

Quoted message said:

Suffice it to say that rotating mass has a neglible impact on acceleration

I wish my legs were as convinced as you are.

Dave

Terry Morse said:

In article said:

Smaller tires are usually lighter. This is good because less energy is consumed when you are
accelerating.

Uh oh, it's the "rotating mass" argument again. Suffice it to say that rotating mass has a
neglible impact on acceleration, and we'll be done with it.

Interested parties can search google for a google of arguments on rotating mass.

okay.

groups.google.comgroupsOpen ↗

"Using Mark McMaster's estimate of weight savings of 20 grams per wheel and a rotational inertial
savings of 40 grams m/s^2, the benefit in a 250 m flat sprint would be of the order of 3.5 cm."

That can be (and has often been) the difference between first and second.

I can't see any reasons not to reduce weight other than the obvious ones: cost and reliability.

In article 3F7883EA.C998262A@hocuspocus_ti.com said:

I can't see any reasons not to reduce weight other than the obvious ones: cost and reliability.

As the saying goes: "weight, cost, durabilty. Choose two."

Tim McNamara said:

In article 3F7883EA.C998262A@hocuspocus_ti.com said:

I can't see any reasons not to reduce weight other than the obvious ones: cost and reliability.

As the saying goes: "weight, cost, durabilty. Choose two."

Yeah, I think it puts it about as concisely as it could be said. I still don't know why Terry thinks
rotating mass doesn't matter (why wouldn't it matter just as much as any other mass on the bike?).
If that were true, we could use stone wheels like Fred Flintstone.

In article 3F78AC77.16022C1D@hocuspocus_ti.com said:

Tim McNamara said:

In article 3F7883EA.C998262A@hocuspocus_ti.com said:

I can't see any reasons not to reduce weight other than the obvious ones: cost and
reliability.

As the saying goes: "weight, cost, durabilty. Choose two."

Yeah, I think it puts it about as concisely as it could be said. I still don't know why Terry
thinks rotating mass doesn't matter (why wouldn't it matter just as much as any other mass on the
bike?). If that were true, we could use stone wheels like Fred Flintstone.

This has been such a longstanding debate and one can find thousands of posts referring to "rotating
mass" and the like. Basically it boils down to this: a bicyclist accelerates so slowly that
differences in rotating mass are not any more significant than differences in total mass. If you're
accelerating from 0 to 30 mph in 1.5 seconds, rotating mass is a more significant factor than if
you're accelerating from 0 to 30 mph in 30 seconds.