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

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  #51  
Old 11-21-12, 05:12
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If rolling resistance is so important, shouldn't we all ditch our racing 23s in favour of 25s
Already have. The 25s are superior in every way.
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  #52  
Old 11-21-12, 05:15
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Originally Posted by Giuseppe Magnetico View Post
When Guesdon won Roubaix in '97 on Michelin Pro2 clinchers we were saying the same things for a minute. I will eat my words if all of a sudden clinchers become the preferred choice for TT's, but I'm not holding my breath. History has a weird habit of repeating itself.
It is a different environment now. A bunch of teams pride themselves on looking for every marginal gain.
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  #53  
Old 11-21-12, 08:41
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Originally Posted by Giuseppe Magnetico View Post
No way in the world you can attribute that time split to a tire because of what an indoor lab test that doesn't recreate real conditions is telling you. A million other factors are defining those times.

I respect you Alex, you've put in a lot of time on and off the bike to promote the sport and you are to be commended. Several of the last 22 years I've worked this industry in marketing and consulting of wheel specific goods, and have sat across the table with companies that have laundry lists of professional race wins, sponsoring the who's who of racers telling me flat out "we have to lie if this is going to sell"! Keep that in mind when you empty your wallet for the sake of chasing the all mighty Unicorn. In the last few years I have since dissociated myself from the kind of work I used to do due to ethical reasons and ran back quickly to what I love to do most, is build wheels that make sense. I'm completely aware that I'm the Atheist in the room of a bunch of religious fanatics.
Who says my tests were not conducted under real conditions, or that the data as obtained from Al Morrison's roller tests don't translate to the real world?

Andy Coggan has a really neat chart showing real world (i.e. road) Crr vs Al's roller test numbers for a range of tyres with a range of Crr values. It's a really nice linear correlation:

http://www.trainingandracingwithapow...ults-part.html

and part I of that item:
http://www.trainingandracingwithapow...t-results.html

You will see that testing on the rollers to assess relative Crr translates well to relative Crr on the road.


Now if we consider the two tyres on Andy's chart in that latter linked item with the least difference between them in terms of Crr, i.e. the
- Veloflex Record clinchers and the
- Bontranger RXL Aerowing clinchers

The impact on speed due to Crr differences is 0.2 seconds per km. Knowing the tyre my competitor did use was considerably worse (over 1 sec/km slower) than mine, I can assure you I know very well that it had a sizeable impact on the result that day.

I have no vested interested in what tyre is the best other than making a sensible choice for best performance according to the criteria I have. I don't give a toss whether it's 19mm or 25mmm, tubular or clincher.

That choice will be an assessment of all relevant performance characteristics, especially aerodynamics, Crr, and suitability for the type of event, amongst others.

I think it was Kraig Willett who said: "faster is faster, right?"

What I am saying is that people should consider the actual data and not be so dogmatic as to believe whether tubs or clinchers or whatever is better.


As as for testing in the real world, you might be interested to know that only last week, for the first time ever, the technology to provide real time Crr data was being calculated and updated on a laptop computer based on data transmitted from a rider riding on a track. Here is the lap by lap data grab from the initial test run:

https://docs.google.com/file/d/0B6tr...Tjg/edit?pli=1

Don't get hung up on the precise numbers or notes in the tables, it was a test of technology to show what we can deliver in real time, rather than a tightly controlled test for Crr.

The technology's primary use is the delivery of real time aerodynamics (CdA) data (wind speed, yaw angles, power, bike speed and lap times where relevant). This was just a test to see if Crr could be delivered in real time as well. It can.

See here for more details on that.
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Old 11-21-12, 08:48
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Originally Posted by simo1733 View Post
If rolling resistance is so important, shouldn't we all ditch our racing 23s in favour of 25s
Because there are several factors to consider when choosing the ideal tyre for a given purpose.

e.g. outright speed in a road TT scenario is primarily a function of Crr and CdA (aerodynamics). Widening the tyre may gain a Crr improvement but worsen the aerodynamics. So one tests to see the overall impact of various factors considered most important for the set purpose.

In a crit there might be other considerations to do with handling characteristics, in training we tend to want better durability, puncture resistance and value for money, and so on.
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  #55  
Old 11-21-12, 14:00
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I turn 40 today, last thing I'm going to do is talk to you nut jobs about tires!!
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  #56  
Old 11-21-12, 14:08
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I turn 40 today, last thing I'm going to do is talk to you nut jobs about tires!!
Happy birthday ya old fart!!

Nice day today, your employer gave you the day off right??

Go ride, gonna be beautiful in the 'republic'. Screw snow and winter!!

Gonna ride this AM..Merckx, tubulars, of course. Clinchers are for nancys.
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  #57  
Old 11-21-12, 16:31
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If rolling resistance is so important, shouldn't we all ditch our racing 23s in favour of 25s

For a given tire presure the contact area with the ground will be constant but a different shape. A long narrow contact area improves traction and helps prevent aquaplaning in wet conditions.
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  #58  
Old 11-21-12, 18:07
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For a given tire presure the contact area with the ground will be constant but a different shape. A long narrow contact area improves traction and helps prevent aquaplaning in wet conditions.
Bike tires do not aquaplane.
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  #59  
Old 11-22-12, 08:38
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I turn 40 today, last thing I'm going to do is talk to you nut jobs about tires!!
Happy Birthday!
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  #60  
Old 11-22-12, 14:43
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I turn 40 today, last thing I'm going to do is talk to you nut jobs about tires!!
Happy Birthday! Turned 40 myself in July.
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