Rolling resistance and why wide tires roll better than narrow tires.

[Sandy]

This is from Schwalbe's website and seems to explain in simple terms why wide tires have less rolling resistance than narrow tires (using the same psi) and why pros use narrow tires.


"What exactly is rolling resistance?
Rolling resistance is the energy that is lost when the tire is rolling and the main reason for loss of energy is the constant deformation of the tire. In addition to rolling resistance, there are also other resistances that have to be overcome when riding a bicycle.

Air resistance rises squared with increased speed. At a straight-line speed of 20 km/h on the flat, air resistance is the main resistance force.

Energy is also required to accelerate. For instance, the weight of the wheels is of great importance when this mass has to be brought up to rotation.

When riding uphill, the main resisting force to overcome is the gradient resistance (descending force).

In addition to these, there are other friction resistances in the chain and all of the other moving parts. Yet in a well-serviced bicycle, these represent a very minor part of the total resistance.



Which factors affect rolling resistance?
Tire pressure, tire diameter, tire construction, tire tread and other factors all have an effect on rolling resistance. The higher the tire pressure, the less is tire deformation and thus the rolling resistance.

Small diameter tires have a higher rolling resistance at the same tire pressure, because tire deformation is proportionally more important, in other words the tire is "less round". Wider tires roll better than narrow ones. This assertion generally generates skepticism, nevertheless at the same tire pressure a narrow tire deflects more and so deforms more.

Obviously, tire construction also has an effect on rolling resistance. The less material is used, the less material there is to deform. And the more flexible the material is, such as the rubber compound, the less energy is lost through deformation.

Generally, smooth treads roll better than coarse treads. Tall lugs and wide gaps usually have a detrimental effect on rolling resistance.


Why do wide tires roll better than narrow ones?
The answer to this question lies in tire deflection. Each tire is flattened a little under load. This creates a flat contact area.

At the same tire pressure, a wide and a narrow tire have the same contact area. A wide tire is flattened over its width whereas a narrow tire has a slimmer but longer contact area.

The flattened area can be considered as a counterweight to tire rotation. Because of the longer flattened area of the narrow tire, the wheel loses more of its "roundness" and produces more deformation during rotation. However, in the wide tire, the radial length of the flattened area is shorter, making the tire "rounder" and so it rolls better.



Why do Pros ride narrow tires if wide tires roll better?
Wide tires only roll better at the same inflation pressure, but narrow tires can be inflated to higher pressures than wide tires. However, they then obviously give a less comfortable ride. In addition to this, narrow tires have an advantage over wide ones at higher speeds, as they provide less air resistance.

Above all, a bicycle with narrow tires is much easier to accelerate because the rotating mass of the wheels is lower and the bicycle is much more agile. At constant speeds of around 20 km/h, the ride is better with wider tires. In practice, the energy saving is even greater than in theory as the elasticity of the tires absorbs road shocks, which would otherwise be transferred to the rider and so saves energy."


Schwalbe Sandy

[G-Reg]

..... At constant speeds of around 20 km/h, the ride is better with wider tires......."





So wider tires are better as long as you don't plan to go over 12.5 MPH?

[mnoble485]

So wider tires are better as long as you don't plan to go over 12.5 MPH?

Yeah but who rides that fast anyhow?:banana:

[Sandy]

So wider tires are better as long as you don't plan to go over 12.5 MPH?

Excellent point. I think such a low speed was used as the graph given (which did not paste when I copied it) depicted two very wide tires in a comparison and those tires are normally inflated at low at psi. However, I do not think the 20/km per hour has anything to do with the logic/analysis given. I would think that a 700x23 road tire would have more rolling resistance than a 700x25 road tire of the same manufacturer and tire model (as long as the psi of both tires is the same).

I am going to use the 700x28 Schwalbe Ultremo ZX tire on a KBedford bike that is being built up at my LBS. I believe that tire will roll better than the 700x25 GP4000 tire I use on my steel Serotta. Initially, I am going to use 95-97 psi in front and 105-107 psi in the rear with the Schwalbe tires, the same psi I use with the GP4000. I will later lower the psi on the Schwalbe to improve ride quality....or at least try and see what occurs.


Sandy

[Sandy]

Yeah but who rides that fast anyhow?:banana:

Schwalbe's comments apply at much higher speeds. Schalwbe did say below that narrow tires can be inflated to a higher psi than wider ones, they will accelerate quicker because of smaller rotating mass and better agility, and that the tires give less resistance at higher speeds. But at higher psi, ride quality is lessened. Wider tires do not transfer as much road shock to the rider so the cyclist does not lose as much energy.


Sandy

[firerescuefin]

http://velonews.competitor.com/2012/05/news/giro-tech-rise-of-the-25c-tire_218011

[sevencyclist]

I understand that at the same pressure, wider tire has less rolling resistance. How about ride quality? At the same pressure, does the wider tire provide better absorption than narrow tire?

I tend to associate the comfort of wider tires coming from being able to run lower pressure, but I might be wrong.

[fiamme red]

I am going to use the 700x28 Schwalbe Ultremo ZX tire on a KBedford bike that is being built up at my LBS. I believe that tire will roll better than the 700x25 GP4000 tire I use on my steel Serotta. Initially, I am going to use 95-97 psi in front and 105-107 psi in the rear with the Schwalbe tires, the same psi I use with the GP4000. I will later lower the psi on the Schwalbe to improve ride quality....or at least try and see what occurs.If wider tires ride better, why not go with 700x32 or 700x35?

[bobswire]

If wider tires ride better, why not go with 700x32 or 700x35?

Weight and aero is a factor too, if your desire is speed.

[fourflys]

If wider tires ride better, why not go with 700x32 or 700x35?

Because most frames won't fit them... But that would be the sweet spot IMHO...

[fourflys]

. Initially, I am going to use 95-97 psi in front and 105-107 psi in the rear with the Schwalbe tires, the same psi I use with the GP4000. I will later lower the psi on the Schwalbe to improve ride quality....or at least try and see what occurs.


Sandy

For comparison I run Clement Strada 28mm on my Salsa and have 85 in the back and 75 in the front and it rides very nice... I'm around 190# BTW...

[fourflys]

Weight and aero is a factor too, if your desire is speed.

Do you really think many of us are going to lose that much speed between a 23mm and a 32mm? The ability to be freasher toward the end of the ride because of the comfort will pay bigger dividends in speed than any aero advantage IMO...

[ultraman6970]

If the thing continues like this, soon we will see road bikes with those moon vehicle type of tyres being used everywhere :)

[Frankwurst]

:beer:Yeah but who rides that fast anyhow?:banana:
Me. 13.7. In a town line sprint.:beer:

[zap]

Much depends on road conditions and how fast one goes.

Snappy Speedy Sandy will be quite happy riding Merryland roads with 25c at 95 psi (my pump-his weight).

King snap pics of that snappy Bedford yet?

[srice]

If the thing continues like this, soon we will see road bikes with those moon vehicle type of tyres being used everywhere :)

I can definitely attest to there is an upper limit somewhere on this wider is better theory. This weekend was my club's, Louisville Bicycle Club, big annual money making ride. I decided to test the wider is better theory and I pulled the bike with the widest tires out of my stable. That was my Pugsley with 4.7" Big Fat Larry tires. It was a beast. So I believe that the answer lies somewhere between 23mm and 4.7".

[fiamme red]

Because most frames won't fit them... But that would be the sweet spot IMHO...Sandy's new bike uses cantilevers, and there are no fender mounts. So he should have room for 700x35 tires.

If Sandy is using 700x28 tires without fenders, why spec cantis instead of long-reach sidepulls?

[fourflys]

Sandy's new bike uses cantilevers, and there are no fender mounts. So he should have room for 700x35 tires.

If Sandy is using 700x28 tires without fenders, why spec cantis instead of long-reach sidepulls?

Not sure but I know my Cass will only fit 28's with fenders and it has cantis... Kind of annoying actually...

[Ken Robb]

I currently ride tires from 700x25 to 700x35 and 90psi to 60psi. One of the reasons I ride fatter tires is so I can use lower pressure for a better ride. I have read and believe that a really skinny tire at very high pressure is fastest on a perfectly smooth surface like a track. The article goes on to say that in the real world of coarse or rough and bumpy pavement a softer tire will be faster because its tread deforms and engulfs/rolls over the imperfections but a very hard tire is effectively pushed back by the little "collisions" created when the rock hard tire encounters surface imperfections.

This seems true based on my butt-meter.:)

[Chance]

I understand that at the same pressure, wider tire has less rolling resistance. How about ride quality? At the same pressure, does the wider tire provide better absorption than narrow tire?

I tend to associate the comfort of wider tires coming from being able to run lower pressure, but I might be wrong.

Wide tires at same pressure seem to ride harsher to me. In my opinion comfort comes from lower pressure and not the width itself. The added width is just a necessary evil to prevent pinch flats if one ran lower pressures on narrow tires. And also to handle the 200+ pound crowd that is becoming more common.

[fourflys]

Wide tires at same pressure seem to ride harsher to me. In my opinion comfort comes from lower pressure and not the width itself. The added width is just a necessary evil to prevent pinch flats if one ran lower pressures on narrow tires. And also to handle the 200+ pound crowd that is becoming more common.
I would tend to agree with this... Not sure why someone would get wider tires and then run the same pressure... Also as Ken said above, the lower pressure allows for more deformation in the tire allowing it to roll over stuff... Also I've noticed less flats, even here in Alaska where a lot of the road is sharper gravel...

[nahtnoj]

I wish they would define what "wider" is.

I think the effort required to accelerate the extra rotating weight of a 35 versus a 28 is going to negate any rolling resistance advantage on a paved surface.

In fact, this was my experience as recently as yesterday.

[fourflys]

I wish they would define what "wider" is.

I think the effort required to accelerate the extra rotating weight of a 35 versus a 28 is going to negate any rolling resistance advantage on a paved surface.

In fact, this was my experience as recently as yesterday.

Good point why most bikes designed for a tire wider than 30mm is a 650b... The smaller size offsets the weight penalty... That's why I said earlier I think the sweet spot for a 700c wheel is 30-32mm... I can definitely say I don't notice any difference between a 25mm ProRace 3 (measures smaller) and the 28mm Clement Strada I use now... I'd be riding the Grand Bois or Challenge 30mm tires if I could fit them in under my fenders...

[Sandy]

Sandy's new bike uses cantilevers, and there are no fender mounts. So he should have room for 700x35 tires.

If Sandy is using 700x28 tires without fenders, why spec cantis instead of long-reach sidepulls?

I will try to answer, but my knowledge of bikes is quite limited. I am not using canti brakes. I am using TRP's CX8.4 mini-V brake. I decided that I wanted to use a carbon fork over a steel fork. I could not use a road carbon fork as the the fork span (distance from axle to fork crown) is too little to accommodate larger tires (700x28.....700x35). I chose the mini-V over the canti brakes as I read many reviews and opinions are it seemed as if the mini-V are much more powerful brakes. As I was not using a steel fork I could not use long reach sidepulls as they would not be applicable to the Enve cross fork I chose. No way to mount them on the fork (I think).

700x35 tires will fit on my bike.

I chose a sport tourer bike for several reasons- one of which was to accommodate tires larger than 700x25-- Very few (extremely limited) carbon road forks will accommodate large tires.

Sandy

[Sandy]

As tire size increases, the max psi of the tire tends to decrease. Lower air pressure with larger volume equates, I think, to better ride quality. That is important to many.


Sandy

[dave thompson]

Sandy, I agree with all of what you've said and done. When I spec'd out my Milholland sports tourer last year, I wanted it to be able to use 28mm tires. I'm using the Ultremo ZX 28s on Velocity A23 rims and those tires measure 31mm across. I'm close to 195#, run approx 90 psi and find the ride and handling just excellent.

One can argue the scientific pros and cons all day long, I find big and wide work perfectly for me. The narrowest tires I have on any bike are 25mm on 23mm rims.

Please post pics of your bike soon.

[Ray]

Do you really think many of us are going to lose that much speed between a 23mm and a 32mm? The ability to be freasher toward the end of the ride because of the comfort will pay bigger dividends in speed than any aero advantage IMO...

Real speed, no, it probably doesn't make much difference for the way most of us non-racers ride. But in terms of perceived speed and particularly the perceived ability to accelerate in changing terrain, smaller and lighter tires often feel faster and more efficient. Which can matter a lot in the enjoyment of a ride. Back when I was riding a lot and actually riding with a computer most of the time, I did a lot of back to back to back rides with 23s on light wheels and 32s on beefier wheels. the actual differences in my average speed from ride to ride were minimal to non-existent - certainly nothing that would matter in the scope of any personal or club ride. But except on the very worst pavement and on dirt, the 32s on the beefy wheels always felt MUCH heavier and less efficient - I felt slower and like I was working harder even if in reality I wasn't. And perception matters a lot to my enjoyment of a ride. I have a fat-tire 650b town bike and I love tooling around town doing errands on it, but any time I've ended up riding more than about 6-8 miles at a time on it, I invariably start to hate it and always wish I has a skinny tire bike.

It really doesn't make a lot of real difference for most recreational riders, so ride what you like. I almost always like skinny tires and fairly light wheels. And I'm really slow in actual fact these days so it's ONLY about feel and perception, but those matter a lot to me.

-Ray

[djg]

"When riding uphill, the main resisting force to overcome is the gradient resistance (descending force)."

Some might say "gravity." You know, the fact that, while I'm staring up the road, my fat tuches wants to accelerate towards the center of the earth at round about 32 feet per second squared.

Also the burrito force, which interacts with the gravitational force.

I dunno, we've all read various versions of the contact patch story, and yeah, there's that. And the fact that rolling resistance, in and of itself, tends to be a rather small part of the story. There are lots of tradeoffs in the Schwalbe explanation, and lots left off. How much work do you do making corrections if your tire is bouncing on rough pavement, or not sticking in corners the way you'd like? I mean, even before we count tensing up, backing off, etc.

Frankly, unless you're going to do very, very comprehensive measurements and optimize across many factors/conditions, I think it's best to sort this out by the seat of your pants. People find the tires they like for commuting, for office park crits, for centuries, for rando events, for gravel road rides, etc. Try what your pals like. Try the next size wider or narrower, 5 psi down or up.

I actually ride 32c tires on pavement plenty, DURING CROSS SEASON. Leave the spendy tubulars at home and ride clincher file treads to work. That's time and miles on the cross bike, with the cross bike setup. And although most of the basic route is paved, there are always places here and there for short forays onto the grass, etc. The wide tires are just fine on the pavement, but they are heavier, and do feel heavier (and I'm not saying that there's a nice neat and fine-grained correlation between what the scale says and how things seem to me JRA). And fine is not great -- they are not at all what I would choose if I were just riding on pavement and wanted to go faster, and push it in corners, even if I were going long and prioritizing not beating myself up. But yeah, they do smooth out the rough bits, even at double or more the pressure I'd use if I were actually racing cross.

[Rueda Tropical]

the actual differences in my average speed from ride to ride were minimal to non-existent - certainly nothing that would matter in the scope of any personal or club ride. But except on the very worst pavement and on dirt, the 23s on the lighter wheels always felt MUCH heavier and less efficient - I felt slower and like I was working harder even if in reality I wasn't. And perception matters a lot to my enjoyment of a ride.

In the end this is the biggest 'performance' factor in recreational riding. Feeling fast is more important then being fast -as your enjoyment is 100% based on perception.

Ceramic bearings, aero rims, the latest tech and whatever tires that make you feel like you are burning up the tarmac - unless you are racing at a high level - their value is really measured in perceived fun factor. It's why someone buys Super Record instead of Chorus. Because in your head you'll always feel like you were missing something even though in reality it makes zero performance difference. You're stuck with the amp that goes to 10 instead of the one that goes to 11.

Like car suspensions on public street -a rig that is actually slower can feel a lot faster and if you think your are Vin Diesel in fast and furious that perception is what counts..

[oldpotatoe]

Because most frames won't fit them... But that would be the sweet spot IMHO...

IMHO..I think for a road bike, used on roads, paved type, is probably in the 25 to 28mm range.

[fiamme red]

I will try to answer, but my knowledge of bikes is quite limited. I am not using canti brakes. I am using TRP's CX8.4 mini-V brake. I decided that I wanted to use a carbon fork over a steel fork. I could not use a road carbon fork as the the fork span (distance from axle to fork crown) is too little to accommodate larger tires (700x28.....700x35). I chose the mini-V over the canti brakes as I read many reviews and opinions are it seemed as if the mini-V are much more powerful brakes. As I was not using a steel fork I could not use long reach sidepulls as they would not be applicable to the Enve cross fork I chose. No way to mount them on the fork (I think).

700x35 tires will fit on my bike.

I chose a sport tourer bike for several reasons- one of which was to accommodate tires larger than 700x25-- Very few (extremely limited) carbon road forks will accommodate large tires.

SandySandy, if rolling resistance is important to you, you should consider these 32mm tires:

http://www.compasscycle.com/tires_gb_700_32.html

[sc53]

I will try to answer, but my knowledge of bikes is quite limited. I am not using canti brakes. I am using TRP's CX8.4 mini-V brake. I decided that I wanted to use a carbon fork over a steel fork. I could not use a road carbon fork as the the fork span (distance from axle to fork crown) is too little to accommodate larger tires (700x28.....700x35). I chose the mini-V over the canti brakes as I read many reviews and opinions are it seemed as if the mini-V are much more powerful brakes. As I was not using a steel fork I could not use long reach sidepulls as they would not be applicable to the Enve cross fork I chose. No way to mount them on the fork (I think).

700x35 tires will fit on my bike.

I chose a sport tourer bike for several reasons- one of which was to accommodate tires larger than 700x25-- Very few (extremely limited) carbon road forks will accommodate large tires.

Sandy
I have ordered a similarly spec'd bike from Kelly as well, also using the Enve cross fork. I have two "wider" sets of wheels, some Velocity A23's with Vittoria Open Corsa CX 25c tires mounted, and a new pair of HED Belgium C2 with Vittoria Hyper Randonneur 35c tires mounted. I have been riding the A23 wheels on my Ottrott for the past couple of weeks and frankly they feel the same as the Dura Ace 7800 wheels with Conti GP4000 25c I was riding on the Ottrott up to now. In fact when I measure the tires on the two sets of wheels they both measure out the same even though one pair of rims is wider. The HED/Vittoria 35c wheels won't fit on the Ottrott so I can't try them out until my Bedford is done (in 8 weeks).
SANDY we are waiting for pix of the built up bike! I opted for paul's touring canti brakes rather than the mini-Vs. My bike is basically identically sized to Karen's, which I rode at Smiley's during my fit process, so I've essentially already had a chance to ride and see my finished bike!

[Chance]

As tire size increases, the max psi of the tire tends to decrease. Lower air pressure with larger volume equates, I think, to better ride quality. That is important to many.


Sandy

Maybe, but riding a smaller tire doesn't preclude using lower air pressure, does it? Tire pressure rating has little to do with anything unless the rider wants to ride very low pressures that may make a "normal" tire come off the rim or to flex excessively. And that's highly unlikely at the pressure range most of us are talking about here. Have ridden 23s at pressures as low as 60 PSI and didn't have any problems at all. Granted, don't weigh over 200 pounds like many riders.

So would agree with lower air pressure equating to better ride quality, but don't know what tire "VOLUME" has to do with it. If it were used in regard/reference to preventing pinch flats it would make sense, but when the word "volume" is used as a means to improve ride it makes no sense at all. Must be missing something because enough people keep repeating the same message.:confused:

[fourflys]

IMHO..I think for a road bike, used on roads, paved type, is probably in the 25 to 28mm range.

Guess I was thinking of being able to go off pavement if needed/wanted a little... I know my 28's are manageable on gravel, but a little wider would be nicer... Guess it depends what you see yourself riding... But I agree, 28mm is pretty sweet on pavement...

[snowcrash19]

Wider rims, smaller tires!

Use a 23mm rim with a 20c tire and it will measure out to 23c when inflated. Probably not an amazing combo to run when its wet out but its crazy light and super fast!

I use the 23c (Maxxis Padrone) on the 23mm rim and it measure 26c when inflated also feels much more like a tubular.

[Mark McM]

While wider tires can have lower rolling resistance, there are more variables that must be considered. Firstly, for otherwise similar tires, the wider tire will have the lower resistance at the same pressure. But one wouldn't typically use the same pressure in the wider tire, because the wider tire would be stiffer and less compliant (harsher ride). You'd normally run the wider tire at a lower pressure, which would tend result in a rolling resistance similar to the narrow tire at a higher pressure.

Rolling resistance data on Terry Morse's web site (http://www.terrymorse.com/bike/rolres.html) show the rolling resistance of several widths of the same model of tires across a range of pressures. Looking at the chart below from the web page, it appears that for a particular model of tire at a given pressure, rolling resistance is inversely proportional to width. For example, the Avocet 20 25mm at 8 bar pressure has the same same rolling resistance as the Avocet 20 28mm at 7 bar (25mm x 7 bar ~= 28mm x 8 bar), and the Michelin HiLite 20mm at 8 bar has the same rolling resistance as the Michelin Hilite 23mm at 7 bar (20mm x 8 bar ~= 23mm x 7 bar).

http://www.terrymorse.com/bike/imgs/rolres.gif


Also, the width/rolling resistance comparison between tires can really on be made with tires of the same construction. Wider road tires tend to be made with sturdier construction (thicker casings, protection belting, thicker treads), which increases rolling resistance. So a sturdily built 28 mm tire may not have lower rolling resistance than a lightweight 20 mm tire, even at the same pressure.