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sufferfest69
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Joined: Wed Jul 24, 2013 2:54 am

by sufferfest69

It doesn't matter how fast a tire "feels"

The reality is that from multiple testing a wider tire at lower psi is faster. Period.

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cmcdonnell
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by cmcdonnell

sufferfest69 wrote:It doesn't matter how fast a tire "feels"

The reality is that from multiple testing a wider tire at lower psi is faster. Period.


Not sure this is correct... I thought the facts were that a wider tyre at an equal pressure had a lower CRR so if you ran the wider tyre at a lower pressure you could have an equal or better CRR than a narrower tyre at that pressure allowing people who found narrow tyres uncomfortable to reduce pressures.
The wider tyre at a high pressure will offer a lower CRR than a wider tyre at a lower pressure.
The wider tyre at a lower pressure may have an equal CRR to narrower tyre at a higher pressure.
The narrower tyre will be more aerodynamic than the wider tyre as the tyre should be narrower than the widest point of the rim but i've seen little data objectively quantifying this.
To me a tyre that is inflated to 25mm (wide in my opinion) is about ideal wheter a clincher (probably a 23mm tyre on a 17C rim) or a 25mm tub.
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Alumen
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by Alumen

sufferfest69 wrote:It doesn't matter how fast a tire "feels"

The reality is that from multiple testing a wider tire at lower psi is faster. Period.


Not entirely true unfortunately...

From the tests you can read that a wider tire at lower psi is faster then a narrow tire at the same psi. But if you run your narrow tire on a higher pressure, the rolling resistance is more or less the same... And even worse, if you run a wider tire on a narrow rim, then it works even contra productive...

Have a look at the links I have added at my starting post.

Summarized..., only rims that are 17C wide and up benefit from the wider tires at lower pressure with slightly less rolling resistance. So basically with wider tires on wider rims you will experience "only" more comfort and some additional grip.

Reading all the pros and cons now, with my 15C Campy rims, I have concluded to go back to 23mm. I ride Conti's, so a 23mm Conti is approximately 25mm anyway so I still will enjoy a good level of comfort. However, I don't care about comfort to much, hence I ride a CAAD10 alloy frame.
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fromtrektocolnago
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by fromtrektocolnago

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springs
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by springs

23's, The truth is I never left you
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I see what you did there.

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mpulsiv
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by mpulsiv

It all comes down to rim profile http://enve.com/products/ses-4-5-ar
For those that like charts :)

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Marin
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by Marin

Shows nicely that all the aero snake oil don't matter at realistic yaw angles of 0 to 5°

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prebsy
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by prebsy

I would suggest everyone read the six part silca journal article about tire width, pressure and aerodynamics. Because of larger internals most aero rims can be run with a 23mm max tire to have the wheel perform any where near optimally. It's a balancing act between traction, aero, ability to run low enough to avoid "bouncing", and high enough to avoid pinching/bottoming out. I feel with tubeless I can hit that balance with a 23 for crits,rr,tt. With tubes I feel I need a 25 to balance the traction needed for crits and min pressure needed to avoid pinching.

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kgt
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by kgt

Marin wrote:Shows nicely that all the aero snake oil don't matter at realistic yaw angles of 0 to 5°

+1

beswiss
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Joined: Sun Apr 08, 2012 2:02 pm

by beswiss

There was a podcast on CyclingTips where they spoke with an engineer of Zipp about wider tires and lower PSI. It was pretty interesting on how the feeling of a high psi tricks the mind and gives a fast feeling due to the road buzz. Even for the engineers who knew the lower psi was faster, the higher one still felt faster.

Link to the podcast: https://cyclingtips.com/2016/08/cycling ... pressures/
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Asteroid
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by Asteroid

My understanding is that track riders use 23 or smaller tires at high pressures.
Do they know something we don't know?

sufferfest69 wrote:It doesn't matter how fast a tire "feels"

The reality is that from multiple testing a wider tire at lower psi is faster. Period.
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pdlpsher1
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by pdlpsher1

One has to keep in mind that the current crop of 23mm tires are really 25mm wide and would be labeled as 25mm a few years ago. The newer 25mm tires are really 28mm wide. So going back to a 23mm doesn't really say much about whether wider is good or bad.

sawyer
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by sawyer

Asteroid wrote:My understanding is that track riders use 23 or smaller tires at high pressures.
Do they know something we don't know?

sufferfest69 wrote:It doesn't matter how fast a tire "feels"

The reality is that from multiple testing a wider tire at lower psi is faster. Period.


They can ride very high pressures because the track surface is so smooth of course

And in those circumstances it makes sense to go for the lightest and most aero set up possible consistent with the rider's handling/grip preferences and the range of wheel width options. So it's not likely they've been on 17mm tyres, but 21mm for example on a narrow-ish rim at 150psi might well be a very fast set up for them in a way it wouldn't be on the road
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Calnago
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by Calnago

pdlpsher1 wrote:One has to keep in mind that the current crop of 23mm tires are really 25mm wide and would be labeled as 25mm a few years ago. The newer 25mm tires are really 28mm wide. So going back to a 23mm doesn't really say much about whether wider is good or bad.

I don't think that's true at all. The reason they measure out wider these days is because they are being mounted on wider rims. A 23mm tire will measure larger on a wider rim than it will on a narrower one (talking about clinchers only here, as tubulars are contained in their own casing and rim width doesn't affect them the same way). If you really want to see how big a 25mm clincher can get, just mount it on a new ENVE front rim. It won't clear a lot of road forks these days. The thing is, while there are variations between manufacturers I think the sizing is still based on the tires being mounted on "normal" rim with a 15mm internal width. Mount them in bigger rims and they expand accordingly.
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fromtrektocolnago
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by fromtrektocolnago

keep hearing that michelin 23's ride wider than other 23's
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