# Is there an advantage in changing to narrower tyres



## wait4me (13 Sep 2012)

I have a Giant Escape 1.5 which after 1400 miles is in need of a new rear tyre. It's had a Maxxis Columbiere 700 x 32 from new. The rim is 622 19 wich will take a 700 x 28 tyre. Here's the questions--
1/ Will I gain much in the less road resistance of the narrower tyre?
2/ I have been very happy with the Columbiere but can't find it in this size. Any recommendations for a similar tyre which also has some (p word) protection?


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## Stonepark (13 Sep 2012)

1)Not a lot in resistance difference, tyre compound probably has more effect friction wise and 28mm will be less comfortable as require higher pressure for narrower tyre
2)Schwalbe Durano plus - a little heavier but about as puncture resistant as you can get,


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## PpPete (13 Sep 2012)

Friend of mine went from 700x35 to 700x23, his hybrid looked chuffing silly, but he didnt half go faster !
Whether going from 32 to 28 will make a huge difference I don't know but I would certainly try, maybe even a 25 !
Durano + are good, or at the budget end, look for Bontrager Hardace RaceLites


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## Norm (13 Sep 2012)

IMO, the width isn't the important factor but the pressure used.


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## wait4me (13 Sep 2012)

Thanks for the help/advice. Off to the LBS tomorrow, see if they can get close to the on line prices


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## Cyclist33 (13 Sep 2012)

http://www.jejamescycles.co.uk/maxxis-columbiere-tyre-700-x-32-id59752.html

Simples.


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## sabian92 (14 Sep 2012)

You'll go faster. _Everybody _wants to go faster.


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## Red Light (14 Sep 2012)

If they are the same pressure, wider tyres will have a lower rolling resistance all other things being equal. The reason wider ones tend to be slower is because wider tyres generally have lower maximum pressures.


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## Dragonwight (14 Sep 2012)

The width of the tyre makes no difference to its rolling road resistance. Material, tread pattern and weight are the things you want to be looking at. As long as you inflate the tyre to the recommended amount the pressure will make no difference.Friction does not depend on surface area as a variable only the coefficent of friction and mass excluding air resistance.


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## GrasB (14 Sep 2012)

Actually at a noticably reduced pressure the *same construction* of tyre will have the same rolling resistance. The problem is most manufactures use a different tyre construction for tyres <25mm & >28mm.

One of the few tyres which uses the same construction across its entire range is the Ultremo ZX line. If I take a 23-622 at 100psi (this the reference rolling resistance) gives the same rolling resistance as a 28-622 at 89psi on a 622-13 rim. However things get even more intresting when you go for a wider rim, take those same 23-622 & 28-622 tyres mount them on a 622-17 rim (as wide as I'd want to take a 23mm tyre). Now the 23-662 now is at 94psi for the same rolling resistance & the 28-622 is down at 83psi. If I do the same test with a Conti GP I get a higher rolling resistance on 28-622 than 23-622 at the same pressure.

I should point out these differences are in terms of 2w maximum at 30mph!


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## cyberknight (14 Sep 2012)

Norm said:


> IMO, the width isn't the important factor but the pressure used.


Norm speaketh some truth , theres been a fair bit about tyre width lately in the cycle rags and seems even the pros are moving to 25s as its been found although the tyre has a wider contact patch because it is wider there is less deformation of the tyre structure the contact patch is not as long .The upshot of this is 25s can roll as well or better than 23s and offer a bit more comfort .
Pity i cant get 25s under my cruds


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## VamP (14 Sep 2012)

And then there's the weight of the darn things...


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## Dragonwight (14 Sep 2012)

If you take two tyres with equal mass and the same coefficent of friction and the only difference is there width they will have exactly the same rolling road resistance leaving aside air resistance thats physics 101. Sheldon Brown actually concluded that in the real world a tyre with a slightly lower pressure and increased deflection would work better due to the poor condition of most roads and I have to say I have found this to be the case and I live in the part of the UK that offically has the worst roads.


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## GrasB (14 Sep 2012)

Dragonwight said:


> If you take two tyres with equal mass and the same coefficent of friction and the only difference is there width they will have exactly the same rolling road resistance leaving aside air resistance thats physics 101. Sheldon Brown actually concluded that in the real world a tyre with a slightly lower pressure and increased deflection would work better due to the poor condition of most roads and I have to say I have found this to be the case and I live in the part of the UK that offically has the worst roads.


Assuming that friction is the only source of losses. I'll give you a clue, it isn't.


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## Dragonwight (14 Sep 2012)

GrasB said:


> Assuming that friction is the only source of losses. I'll give you a clue, it isn't.


 
Dont be so cryptic do tell us what are the other losses that make a difference and supply sources so we can all see and be educated.


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## GrasB (14 Sep 2012)

A quick google would have resulted in a wikipedia article. In which the second sentence is:


> It is mainly caused by non-elastic effects, that is, not all the energy that is needed for deformation of the object is recovered when the pressure is removed.


Ergo, the main factor of rolling resistance is the amount of energy it takes to deform the tyre, absolutly nothing to do with frictional losses.


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## Dragonwight (14 Sep 2012)

GrasB said:


> A quick google would have resulted in a wikipedia article. In which the second sentence is:
> 
> Ergo, the main factor of rolling resistance is the amount of energy it takes to deform the tyre, absolutly nothing to do with frictional losses.


 
Here you go hope this helps. As you can see the deformation of the tyre is caused by the mass or weight applied. Hence why i said the only forces to be concerned about really are your weight and the coefficent of friction.
*Rolling friction equation for tires*

You can apply the standard friction equation for rolling wheels to try to determine the value of rolling friction. That equation is
*FR = μRW*​where:

*FR* is the resistive force of rolling friction
*μR* is the coefficient of rolling friction for the two surfaces (Greek letter "mu" sub R)
*W* is the weight of the wheel plus the weight of the person\bicycle
*μRW* is *μR* times *W*


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## GrasB (14 Sep 2012)

The coefficent of friction is mute in these equations (it's about 2.5w @ 100mph iirc) & weight it's self doesn't actually tell you how much you're being slowed down by the deformation of the tyre!


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## Dragonwight (14 Sep 2012)

GrasB said:


> The coefficent of friction is mute in these equations (it's about 2.5w @ 100mph iirc) & weight it's self doesn't actually tell you how much you're being slowed down by the deformation of the tyre!


 
Which just confirms what I have said that the only two variables are the coefficent of friction and mass excluding air resistance and surface area makes no difference.


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## Accy cyclist (14 Sep 2012)

Norm said:


> IMO, the width isn't the important factor but the pressure used.


 

Serious question Norm....If i could pump 100psi into my touring tyres would i be able to do the same speed as 100psi in a narrow road(schwalbe Lugano)tyre?


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## Norm (14 Sep 2012)

I don't know whether using the same pressure would give the same level of squish in the sidewalks. Intuitively and all other things being equal, I'd think that a fatter tyre would need more pressure to be as rigid as a narrower tyre, but all things are not equal and you'll have different construction techniques etc used In the two.

I'll happily defer to others on the details of the subject, though.


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## StuartG (15 Sep 2012)

Thinner tyres have less mass so improving acceleration and deacceleration. So, other things being equal, they 'feel' faster.

Oh and they pump up faster!


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## GrasB (15 Sep 2012)

Dragonwight said:


> Which just confirms what I have said that the only two variables are the *coefficent of friction* and mass excluding air resistance and surface area makes no difference.


Power isn't actually effected by mass a huge amount, in other words if we keep the tyre pressure the same the Crr drops as weight increases. So if we take my high-racer at 50mph unloaded it takes 148.8w to overcome Crr. If it's loaded up with all my gear etc for work, that's another 8kg or so the extra power required is 0.3w, if I extrapolate out the same tyre droop I find that the power consumption of the tyre would be the same +/-0.02w. However if the Crr stayed the same the extra power would be very close to 10w.


Now let's take a look at the coefficient of friction. So the tyre with the highest coefficient of friction are my Schwalbe Ultremo ZXs the 23-622 tyres give a Crr of 0.00621 on my TT bike, if you look at my least grippy tyres at the same size & at the same pressure, Schwalbe Durano, their Crr is 0.00711. In the middle with regard to coefficient of friction there's the Conti GP with a Crr 0.669. So the coefficient of friction appears to be inversely proportional to Crr.

The only thing that's really left is tyre deformation, which guess what, is where all the R&D for tyres go in terms of reducing the rolling resistance.



Accy cyclist said:


> Serious question Norm....If i could pump 100psi into my touring tyres would i be able to do the same speed as 100psi in a narrow road(schwalbe Lugano)tyre?


Probably not, the touring tyre construction would be heavier so you'd use more power deforming the tyre.


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## al78 (15 Sep 2012)

Dragonwight said:


> Which just confirms what I have said that the only two variables are the coefficent of friction and mass excluding air resistance and surface area makes no difference.


 
What about the ease at which the tyre deforms under load?


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## Cyclopathic (16 Sep 2012)

Re the original question...A simple yes or no.


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## dellzeqq (17 Sep 2012)

yes


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## RecordAceFromNew (17 Sep 2012)

All else being equal, the effect of tyre width on rolling resistance per se is very limited, as GrasB indicated in one of the above posts, as well as concluded by Schwalbe in some of their experiments.

What do make a hell of a lot of difference to rolling resistance, all else being equal, are:
1) pressure, where as Norm said high pressure would reduce rolling resistance quite significantly (see e.g. these test results) assuming you are cycling on smooth roads (else the opposite is true!), which therefore has implication on choice of tyre since different ones, even within the same "model" and the same make, can have different pressure rating - though generally speaking narrower tyres tend to have higher pressure ratings, and
2) tyre choice, which can easily make a difference of over 50% to rolling resistance even between 23mm road tyres, and therefore ~10% difference on overall power requirement at 35kph as demonstrated by results in these tests.


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