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PostPosted: Mon May 28, 2012 12:14 am 
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Just an observation of tires used for the final Giro TT - that despite all the noise these days about wider tires on wider rims, checking through this VeloNews link the vast majority of those featured were 21 or 22mm wide, with only a few 23's and even some 19's.

http://velonews.competitor.com/2012/05/ ... ces_221423


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Posted: Mon May 28, 2012 12:14 am 


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PostPosted: Mon May 28, 2012 12:23 am 
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And Ryder was on a top secret tire...
http://velonews.competitor.com/2012/05/ ... velo-p5-14


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PostPosted: Mon May 28, 2012 1:27 am 
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I like this write-up from http://www.schwalbetires.com/tech_info/ ... resistance" onclick="window.open(this.href);return false;

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.


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PostPosted: Mon May 28, 2012 5:56 am 
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Rodriguez on clinchers or just alu. rimmed tubulars?


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PostPosted: Mon May 28, 2012 7:56 am 
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You are missing the point.... Tire width needs to be matched to rim width. If a team is using wheels with an old-fashioned profile like campag, fulcrum etc. then 21s still faster (although some people say a 21 is quicker on the front wheel on some wheels that are optimised for 23s). Some well-resourced teams e.g. Sky, Rabo are using unlabelled wheels because the Shimano ones aren't up to muster. Apparently the latest generation of clincher wheels are quicker than their tub counterparts because a tub is round and is more likely to cause a little gap in the profile where it is glued to the rim, compared with a wide clincher bead.


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PostPosted: Mon May 28, 2012 8:15 am 
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I thought the wider rim improvements apply to clinchers ? (More sidewall mean less bulbous shape which improves ride and handling)

Don't most of the pros ride tubular anyway ?

cheers
Jim


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PostPosted: Mon May 28, 2012 2:24 pm 
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You are thinking of ride quality improvements, which are a lot harder to measure!

Aerodynamically you need to achieve a smooth profile for best results, 21 mm width tub rim means 20-21 mm tire.

Interesting tire developments from Schwalbe here:
http://www.bikeradar.com/road/gallery/a ... h-34116/23


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PostPosted: Mon May 28, 2012 4:21 pm 
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metanoize wrote:
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.


I'm sorry, but the weightloss between 21 and 23 mm tire is so small that it's almost certainly undetectable in accelerating speed.

Aero beats weightloss every time, especially with wheels (hence diskwheels)

Likeliest explanations:

1. The pro's simply don't know better (Most cyclists still don;t care about tech)
2. The gains are so small that it's not worth the hassle of rebadging non-sponsor gear.


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PostPosted: Mon May 28, 2012 7:58 pm 
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[quote="Franklin

I'm sorry, but the weightloss between 21 and 23 mm tire is so small that it's almost certainly undetectable in accelerating speed.
[/quote]

This is true. Vittoria advertises 5g difference between a 23mm, and a 25mm Evo CX.

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Posted: Mon May 28, 2012 7:58 pm 


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