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PostPosted: Mon May 13, 2013 9:37 am 
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Joined: Thu Mar 01, 2012 2:10 am
Posts: 241
I put some new Michelin Pro Optimum (25c) tires on my new 23 mm rims a few months ago and was amazed by how large they were. Frame clearances became a bit marginal. The ride is very plush and comfortable however! So on the weekend I took an opportunity to compare a Michelin 23c tire, the Pro Optima 25c and a Continental Gatorskin 25c on both the 23mm rim and an old 19 mm rim. This is the results.
Image

'Total width' is the width of the unmounted tire carcass, laid flat.
Fascinating how a small difference in tire width is carcass between the Michelin and Continental 25c tires is amplified by the 23 mm rim.

I'm basically running on 28 mm tires. :lol:


Last edited by Rush on Fri Mar 28, 2014 11:04 am, edited 1 time in total.

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Posted: Mon May 13, 2013 9:37 am 


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PostPosted: Wed May 15, 2013 1:35 am 
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Joined: Fri Oct 28, 2011 3:25 am
Posts: 781
Location: United Kingdom of Great Britain and Northern Ireland
How are you measuring rim width? You might be assuming that every tire fits onto every rim, but there are limitations. If your rim is actually 23mm wide, then you just souldn't be using tyres in the 23-25c range. See the table in the 'Which tyre fits which rim' section. http://www.schwalbetires.com/tech_info/ ... nsions#rim" onclick="window.open(this.href);return false;

And these are the reasons why tyres are often not the width as stated on their sidewall:

Standard tire widths are calculated using fairly wide, standard rims. Yet in practice, narrower rims are used more often, which in turn leads to tires becoming slightly narrower as well.

In order to ensure that tires have sufficient frame clearance, tire
manufacturers generally prefer to keep production closer to the lower end of the permitted tolerance (+/- 3 mm).

Carcass casing materials have become more and more sophisticated over time, that reduces the tire widening after the fitting. In order to correct this tire widening, over the past few years slightly wider carcasses have been used, so that the actual widths are now much closer to the standard widths.


From the Schwalbe north America webite, address above.


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PostPosted: Wed May 15, 2013 3:32 pm 
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Joined: Tue Feb 05, 2013 8:29 pm
Posts: 236
Are you measuring inner or outer width of your rims? Brake track width does not correspond to clincher bead width. For example, Zipp Firecrests have a 25mm width at the brake track, but 16.25mm bead width.

Manufacturers generally quote the overall brake track width on their wheels, but you really ought to be measuring the width where the bead actually lies to give more accurate data.


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PostPosted: Wed May 15, 2013 6:57 pm 
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Joined: Sat Apr 18, 2009 8:59 am
Posts: 542
Location: Surrey UK
Obviously Hed C2 it's 23mm wide rim with as my memory serves well 17 or 17.5mm internal width.
With my experience, tires gained about 2mm on the 23/17mm, compared to the standard 19mm rims.
I didn't measure the height.

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PostPosted: Thu May 16, 2013 12:13 pm 
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Joined: Mon Sep 10, 2012 2:37 pm
Posts: 71
Relevant web page with lots of good info.

http://www.slowtwitch.com/Tech/Implications_of_Rim_Width_2803.html

imho, 23c tyres are the idea aero solution for the wider style rims, and generally anything above or below are not as optimal. But going wider to 25c is ok depending on the road surface requirements.

I also believe that the older narrowers rims are at their ideal aero solution with 20mm tyres. And should probably still be the rim/tyre combo choice for track or even crit racers (as road condition is usually pretty close to perfect or is perfect).

But the 20c fad is being phased out somewhat now, because many many people where already using a 23c tyre on a rim optimised for 20c. And it is a no brainer that the 23c tyre matches up to the 23 wide rim

The new wide rim designs are as aero (or more aero depending on wind conditions) as the old 20c tyre/20mm brake track rim ideals. It will just take time for the whole bike industry to move to it solidly.

Their will still be a niece market for 20mm wide rim and tyres, but it won't be the mainstay within a few years I reckon.

(note '23 wide rim' refers to most wide rim aero designs. Some are wider already by the brake track, and even more wider further from the track. Just trying to keep the info somewhat joined properly)


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PostPosted: Sun Mar 23, 2014 11:51 pm 
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Joined: Sat Mar 19, 2011 12:04 am
Posts: 31
Location: Davis, CA
I'm on a set of HED Belgium Plus rims, 25mm external, 20.5mm internal width. Previously had two to of 23mm rims, and 25 is indeed better. Internal width is what matters; some of the 23mm rims have internal widths equivalent to standard external width rims, so won't see a benefit. Also, HED is tubeless compatible.

Schwalbe One tubeless 700x23 measures 26.2 at 75psi on Belgium Plus, IRC Prolite Tubeless 700x25 measures 28 at 75psi.


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Posted: Sun Mar 23, 2014 11:51 pm 


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