Tyre pressures.....

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reohn2
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Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 10:16am

If you thought high TP's help,check out this article about tyre sizes and pressures in last year's Paris Roubaix:-
http://velonews.competitor.com/2012/04/ ... ing_212925

Yes they're tubulars and yes the roads were tough,though mostly the riders are lightweights and the speeds are a lot faster we'll ever ride at especially over cobbles.
Food for Thought?
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meic
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Re: Tyre pressures.....

Postby meic » 17 Apr 2013, 10:56am

Lower than I would have guessed.
Any reasonable estimates of the combined weight of bike and rider?
Were those figures for particular riders and influenced by different (unknown) weights, or some sort of "team average"?
Yma o Hyd

reohn2
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Re: Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 11:21am

meic wrote:Lower than I would have guessed.
Any reasonable estimates of the combined weight of bike and rider?
Were those figures for particular riders and influenced by different (unknown) weights, or some sort of "team average"?

Check out Boonan's TP's,he's a big rider 70/75kgs?
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mig
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Re: Tyre pressures.....

Postby mig » 17 Apr 2013, 11:45am

how many of the wheels will just be condemned by the teams though after that race using those pressures?

byegad
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Re: Tyre pressures.....

Postby byegad » 17 Apr 2013, 11:53am

Harder tyres are faster, on a smooth surface. Once the surface is rough enough to vibrate the bike up and down you are losing speed, the energy for this 'rattle' comes from the rider. So the rougher the road the lower the pressure that is fastest, until you start getting pinch flats!
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reohn2
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Re: Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 1:46pm

byegad wrote:Harder tyres are faster, on a smooth surface. Once the surface is rough enough to vibrate the bike up and down you are losing speed, the energy for this 'rattle' comes from the rider. So the rougher the road the lower the pressure that is fastest, until you start getting pinch flats!

Exactly!
And every road(tarmac) I ride is rough,to a greater or lesser extent.
We don't do smooth tarmac in the UK,generally.There are some areas worse than others but generally UK roads are cr@p,they're badly maintained and badly laid,so appropriate TP's are called for,which are a lot lower than some think,which was my reason for the thread.
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[XAP]Bob
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Re: Tyre pressures.....

Postby [XAP]Bob » 17 Apr 2013, 1:50pm

About 20-30% of my commute has recently been resurfaced - it' like a billiard table - lovely.

Of course 30-40% of it has had "surface dressing" and is just ${EXPLETIVE} awful, 6+ months on and there are still gravel patches...

The rest is mixed, most of it needs relaying properly, some of it is quite new, but they've gone and added another layer which is SO much worse than potholes...
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
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reohn2
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Re: Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 1:52pm

mig wrote:how many of the wheels will just be condemned by the teams though after that race using those pressures?

What's that got to do with anything?
The only time a wheel rim is damaged on a rough road is when the tyre is compressed to the rim making the rim take the hit,in that situation you'll most likely get a snakebite puncture.
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Brucey
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Re: Tyre pressures.....

Postby Brucey » 17 Apr 2013, 2:01pm

They are balancing the need for speed with the need to ride on this stuff;

Image

I would venture to suggest that this is just a leetle-bit-rougher than average UK tarmac...?

Or is it a bit worse round where you are...? :shock:

cheers
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byegad
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Re: Tyre pressures.....

Postby byegad » 17 Apr 2013, 2:06pm

Well it doesn't have the potholes we have for a start! :D Imagine removing, at random 10% of the cobbles, dousing with a years worth of motor traffic and rain, ice and drought and you'd be getting there.
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Mick F
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Re: Tyre pressures.....

Postby Mick F » 17 Apr 2013, 2:30pm

Brucey wrote:They are balancing the need for speed with the need to ride on this stuff;
Even I would ditch my 23mm Vittorias for that! :D

I have - and do - ride on cobbles like that, but not far, and not fast. I remember riding up the steep hill in the rain through the middle of Alston a few years ago up the wet cobbles. I was on 20mm Vittorias then, and pulling a heavy trailer. Hardest thing was getting traction!
http://maps.google.co.uk/maps?q=alston& ... 02,,0,18.1
Mick F. Cornwall

Brucey
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Re: Tyre pressures.....

Postby Brucey » 17 Apr 2013, 3:49pm

byegad wrote:Well it doesn't have the potholes we have for a start! :D Imagine removing, at random 10% of the cobbles, dousing with a years worth of motor traffic and rain, ice and drought and you'd be getting there.


Not that I think the roads are lovely (far from it...) but;

I've always had the impression that, on a low-slung trike, you are three times as likely to go into a hole randomly, and about three or four times less likely to see a bad one coming up because of the low vantage point (or have I missed something?).

If so the net result is that potholes are ten times more of a problem overall...?

cheers
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reohn2
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Re: Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 3:53pm

Brucey wrote:
I would venture to suggest that this is just a leetle-bit-rougher than average UK tarmac...?

Or is it a bit worse round where you are...? :shock:

cheers

My point was one of comparison,there are a lot of people who think the pros ride 23mm @ 120psi front and rear whatever.It ain't so.
I've seen people on here post that they ride 32mm tyres at 95psi thinking they'll go faster :?

Smooth tarmac with little imperfection in warm climates can be ridden on light very narrow tyres at high TP's,mostly I ride some pretty rough,textured,potholed stuff that feels aweful on anything less than 28mm tyres at low TP's.Cobbles/gravel/and even rougher roads, are way better on 35mm supple rubber at looow pressures(50f 70r)which offer comfort even at speed and I don't feel like I've been beaten up after four hours of riding.
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reohn2
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Re: Tyre pressures.....

Postby reohn2 » 17 Apr 2013, 4:17pm

[XAP]Bob wrote:About 20-30% of my commute has recently been resurfaced - it' like a billiard table - lovely.

Of course 30-40% of it has had "surface dressing" and is just ${EXPLETIVE} awful, 6+ months on and there are still gravel patches...

The rest is mixed, most of it needs relaying properly, some of it is quite new, but they've gone and added another layer which is SO much worse than potholes...


There's a couple of two miles long stretches of new(4 years ago)road near us,that was billiard table smooth when laid.
Within 12months they'd begun to come unstuck,they are now falling apart with potholes everywhere,some of which have been repaired twice.The initial new tarmac was poor quality IMHO and the repairs are TBH diabolical.
But that's the norm unless the road is classed as an "A".
We'd better get used to it as the road system is in such a bad state of disrepair,even if the money was available(which it clearly won't be for a looonnnggg time) it'll take a few years of serious work to get it back something like good,but once the standards are lowered and accepted they'll most likely remain IMO.
So real world scenario from a cycling tyres POV needs looking into and some realistic tyres and TP's to handle what can only be described as cr@pmac.
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PeterBL
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Re: Tyre pressures.....

Postby PeterBL » 17 Apr 2013, 4:37pm

Is Boonen running above or below the 15% tyre drop rule of thumb?