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23mm v 25mm Tires

Which tyres for Paris-Roubaix? Whose time trial bike is fastest? Suspension mountain bikes or singlespeeders? Talk equipment here.

23mm v 25mm Tires

30 Apr 2010 21:31

I have always ridden 23mm tires except for a recent touring trip where I rode 25mm tires. But I am not sure why I, most cyclists I know, and professional cyclists ride on 23mm tires if the rolling resistance is less on 25mm tires.

Is it because of the increased weight of 25mm tires?
Is it because of the higher pressures you can use in 23mm tires?
Are any of these offset by the decreased rolling resistance of 25mm tires?
Is there something else that I am missing?
"If you're going through hell, keep going." - Winston Churchill
User avatar elapid
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01 May 2010 01:47

On rough surfaces the 25's will be faster and more comfortable. On smooth surfaces a narrow tire at high pressure will be faster. It all comes down to conditions. Riding a 25 on the rear and a 23 on the front can be a good compromise.
Cheers...Daryl

-Life is too important to be taken seriously-
User avatar Black Dog
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01 May 2010 03:01

elapid wrote:Is there something else that I am missing?


Yes, pros don't ride 23mm clinchers, usually on 21 or 22mm tubulars, 24, 25, 27 or 28mm for the ruff stuff.

Personally I ride clinchers most of the time, the biggest I can stuff in the frame, 25 or 28's depending on what rig I grab. I seek out gravel road sections on every road ride though. Endless miles of smooth pavement gets boring IMO, unless you're going uphill a lot. For my hilly rides I'm on 22mm Conti tubulars.
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User avatar RDV4ROUBAIX
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01 May 2010 06:08

I have ridden 25mm for the past 8 or 9 years. They just ride better, and if I really want to lighten up, I will lose a little more weight (down 52 in the past year). The difference between 23 and 25 is pretty significant on chip seal and or generally rough roads in Corpus Christi.

I remember riding 18's in the late 80's and early 90's, but moved to 20, then 23 as I got older and enjoy being on the bike much more now.

On clinchers I feel a much more sew-up bite when I corner. The tires are rounder and corner better...
User avatar FFWally
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01 May 2010 12:21

[quote="elapid"]

I suppose there's three other possible factors:

1: the herd instinct - everybody else rides 23's, so I should too.
2: aerodynamics - which favours even skinnier tyres.
3: seat and chainstay clearance?
rgmerk
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01 May 2010 12:37

I've never really thought about it, but it's just a mind thing... road bike=23mm, my old hybrid=25mm.

having just done Paris-Roubaix on 28mm on the road bike I am wondering where to use the 28's again (other than for Flanders next year)... they were fine to ride on and I must admit I'm getting tired of the crap conditions of the roads here in London for commuting...
User avatar Archibald
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01 May 2010 14:20

Archibald wrote:I've never really thought about it, but it's just a mind thing... road bike=23mm, my old hybrid=25mm.

having just done Paris-Roubaix on 28mm on the road bike I am wondering where to use the 28's again (other than for Flanders next year)... they were fine to ride on and I must admit I'm getting tired of the crap conditions of the roads here in London for commuting...



28mm GP 4 seasons are the best tires out there IMO. I'll never ride anything less than 25mm again and won't buy a bike that can't accomodate at least a 28mm.

Air is the best technology there is for vibration damping.
User avatar buckwheat
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01 May 2010 21:02

as a very young triathlete scouring magazines in the late eighties i took the go-fast wisdom of the time of riding 19mm clinchers-------(back then i was 73kg)

I kept wrecking sidewalls of my tyres cos clinchers get a square shape when the bag is so small thus making sidewall vulnerable... and handling is thus compomised in the corners

Now profile roundness is my God of tyres - by that I mean having a consistent contact patch with the road-one with no edges or changes to the nature of my connection to the road when leaning over.

Weight
only becomes an issue when racing- I don't train in groups much and I don't ride with a speedo- to worry about the performance issues when not racing would be... delusional.
Comfort on the other hand is always appreciated!

Now (78-80kg- still lean!) My race bike is a C'dale six13-
when racing I ride deep zipp tubulars 21mm...they are really round so cornering is a pleasure in terms of consistent grip.
ONLY race km's on these due to cost and inconvenience of punctures

If not racing I ride a cheap set of 28mm clinchers ... I was surprised they fit in there....They look sick!! handling is awesome-I have raced them on a day the wind came up too gusty for the deep sections... for general riding they are lovely
User avatar Fred Thistle
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01 May 2010 21:16

elapid wrote:I have always ridden 23mm tires except for a recent touring trip where I rode 25mm tires. But I am not sure why I, most cyclists I know, and professional cyclists ride on 23mm tires if the rolling resistance is less on 25mm tires.


Who says there is less rolling resistance on 25mm tires? You may have read that test by fat tire makers but their caveat is "at the same tire pressure." Well, it is inappropriate to run 23 and 25 at the same psi so basically what they were saying is that if a 23 is underinflated it'll have the same rolling resistance as a 25mm. But when it's properly inflated, it'll have less of course (on smooth roads).
[color="RoyalBlue"]Thirst is stronger than the rules. [/color]- Stars and Watercarriers, 1974
stephens
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tyres or tied up?

02 May 2010 11:06

there was a good blog on here from cervelo re tyres rolling resistance etc but they were for tubs not clinchers and I think that makes a difference. 23mm seems to be the order for the peleton aside of roubaix where 25-28mm ruled.

however many frames won't accommodate anything bigger than a 25mm and it's sometimes a squeeze with that. I have a kuota kom and a 25mm is very, very tight, 28mm impossible.

I did flanders sportive on conti gp4000s 23mm and was fine (reletively), no punctures. if I was commuting I'd get a cross frame and some 28-32mm for sure. I live in central london and often get the train out to e.croydon or surbiton to avoid the real potholes and cars.
maratsafin
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02 May 2010 22:38

stephens wrote:Who says there is less rolling resistance on 25mm tires? You may have read that test by fat tire makers but their caveat is "at the same tire pressure." Well, it is inappropriate to run 23 and 25 at the same psi so basically what they were saying is that if a 23 is underinflated it'll have the same rolling resistance as a 25mm. But when it's properly inflated, it'll have less of course (on smooth roads).


Good question. I had heard that 25mm tires had less rolling resistance than 23mm tires and never backed it up. Sheldon Brown apparently refutes this claim. Digging deeper, it seems as though it is very tire dependent. See http://www.terrymorse.com/bike/rolres.html, or more specifically http://www.terrymorse.com/bike/imgs/rolres2.gif where the rolling resistance of Specialized and Avocet clinchers are compared. Within the different types of Specialized tires, the rolling resistance is greater for 28mm than 25mm tires. But the Avocet tires are all over the place with some 25mm tires having greater rolling resistance than 28mm. When comparing between tire manufacturers, the general trend seems that the larger width tires have greater rolling resistance than smaller widths, but this is not consistent.

But to throw some mud into the debate, there is this from the Schwalbe Tire website (http://www.schwalbetires.com/tech_info/rolling_resistance#why):

"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."

However, as Stephens points out, the rolling resistance of different width tires are tested at the same pressure, while smaller width tires can be inflated to higher pressures than wider tires thus reducing road contact and rolling resistance. The Schwalbe Tire website continues:

"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."

So, to answer my own questions: narrower tires are used by most of us because the higher pressures reduce rolling resistance (and the rolling resistance comparison of different tire widths is essentially biased because they are tested at the same pressure rather than ideal pressures for each width of tire), and the weight savings and profile improve performance. However, wider tire widths provide a more comfortable ride and, as a result, may save energy.
"If you're going through hell, keep going." - Winston Churchill
User avatar elapid
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03 May 2010 12:25

elapid wrote:So, to answer my own questions: narrower tires are used by most of us because the higher pressures reduce rolling resistance (and the rolling resistance comparison of different tire widths is essentially biased because they are tested at the same pressure rather than ideal pressures for each width of tire), and the weight savings and profile improve performance. However, wider tire widths provide a more comfortable ride and, as a result, may save energy.


Well, sort of. What are the real savings in wind resistance with a 2mm reduction in tire profile? Does it matter in a road race...no. In a time trial...yes. As for weight, especially rotational weight, this is another marketers brain wash. Saving 25-50 grams of tire weight does not really make the wheel harder to accelerate in any way that the human body could perceive. The claim of performance gains is simply unfounded, in that, the gain is so small as to be virtually insignificant. Final score: Marketing 1 million - Cyclists 0.
Cheers...Daryl

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User avatar Black Dog
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03 May 2010 12:36

Black Dog wrote:edited.... As for weight, especially rotational weight, this is another marketers brain wash. Saving 25-50 grams of tire weight does not really make the wheel harder to accelerate in any way that the human body could perceive. The claim of performance gains is simply unfounded, in that, the gain is so small as to be virtually insignificant. Final score: Marketing 1 million - Cyclists 0.


As has been said in the frame materials thread, the score is more like marketing 1 million - Cyclists 1 million. Because cyclists are so addicted to cycling they are just looking for a reason to shower their true love with more of their hard earned cash.

Between women and cycling, we are doing our part to keep the economy rolling along.

Selling promises to cyclists is like fish in a barrel. And don't even get me started on the whole 'women' thing.
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03 May 2010 12:52

I just don't see racers using anything but the best tires available to them. Can you think of any other sport where the participants use something that leaves them at a disadvantage just because of "marketing"?
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stephens
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03 May 2010 13:03

stephens wrote:I just don't see racers using anything but the best tires available to them. Can you think of any other sport where the participants use something that leaves them at a disadvantage just because of "marketing"?


Huh? Best? Do you mean best marketed or best performing? These things are not always the same. Having the "best" does not mean that it will be any better than other options. That is the point of all this.
Cheers...Daryl

-Life is too important to be taken seriously-
User avatar Black Dog
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03 May 2010 14:11

Lots of pro riders use less than optimal equipment. Riders changing equipment due to sponsor changes, use equipment they don't like. Matti Breschel and Michael Rasmussen have both been complaining this season over injuries caused by a new bicycle from a new sponsor. Matti Breschel got a knee injury because he used the specialized bike made especially for the Paris Roubaix instead of his normal bike. Michael Rasmussen also got problems when switching to a new bicycle brand after he got employed by the Miche team.

In addition I guess a lot of riders were "forced" to use the carbon rims supplied by their sponsor in the cobbled classics. I am not sure it was a disadvantage though. Zipp carbon 404 in Roubaix: 1st, 2nd, 4th and also 1st in Flanders.
analo69
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03 May 2010 23:01

analo69 wrote:Lots of pro riders use less than optimal equipment. Riders changing equipment due to sponsor changes, use equipment they don't like.


What proportion of pros use something other than the team sponsor's saddle?

After going from a torture device to something that's marginally acceptable for long rides (switching to bib shorts helped a lot, am going to try the Selle SMPs to see how they go) the thought of being forced to use a non-preferred saddle on a Grand Tour sounds like, well, torture.
rgmerk
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04 May 2010 01:21

Full bodied, nice 'n' round... mmmm
the bigger the cushion, the sweeter the pushin'

for TRAINING I am in luuuurve with my 28's... I even race 'em from time to time. Pumped up HARD of course
User avatar Fred Thistle
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what about 24mm?

04 May 2010 13:19

I'm riding 24mm now and frankly I can't tell them apart from 23mm, or 25mm. I must be slipping.
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05 May 2010 17:41

analo69 wrote: Matti Breschel got a knee injury because he used the specialized bike made especially for the Paris Roubaix instead of his normal bike.


You mean "Specialized" the brand?

If so I guess Specialized is laughing their collective a$$ off that a rider thinks the Roubaix causes knee injuries as opposed to the non knee injury inducing Tarmac.
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