# Tubular PSI?



## Keeping up with Junior (Feb 27, 2003)

Just slapped some Conti Comps (22) on my Reflex rims and curious what pressure folks would recommend running. Raced on them at 120psi last weekend and was happy, not too soft but not too hard. Just looking which direction to experiment until I settle on a happy psi number.

Looking for use in road races on good surfaces. I am 160# and on my training wheels run Michelin Pro Race at 110psi. Previously running Tufo HICC at 125psi, definitely find the Conti's feel better and a bit more confident cornering.


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## Spunout (Aug 12, 2002)

I weight 150 and would ride a smooth course 100 front and 105 rear with 22mm tires.


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## Kung Fu Felice (Apr 17, 2007)

Is it true that what gives tubulars their comfortable "feel" is because they can be ridden at pressures lower than clinchers without fear of a pinched flat? Something like 85psi for a 150lb. rider?


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## oneslowmofo (Feb 29, 2004)

I just switched to tubulars on one of my bikes - Veloflex Carbons. On my other bik, I'm running Veloflex Black clinchers which I normally ride at 110 PSI front and back.

On the tubies, I've been running 120 and they feel noticably softer than my clinchers. I don't know why. I would probably go up to 130psi and they'd still feel softer than the clinchers at 110.

Besides, the solf "feel", I was surprised at how much better tubies corner than clinchers. They just lean over much more comfortably than any clincher that I'v ridden.


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## Bianco (Sep 22, 2004)

Bringing this thread back to life....
a tubular's max psi can be 180+ is this correct? I am 195 pounds, so I'd think the more psi the better. 
What are the pros/cons of taking the psi that high?
I know clincher rims have a max psi, not just the tire, but do tubular rims also have a max psi? 
Does anyone know what the tdf pros pump their tubies too? I usually run my Conti gp4000 clinchers to 125, but I'm thinking of switching to tubulars.


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## filtersweep (Feb 4, 2004)

I rode mine at 140+ the other day, just to compare... and it was harsh. I could see riding on a nice track with high pressure. But on the street it was just nasty. It felt like riding 19s or some other thin tire-- maybe because I actually ended up with such a small contact patch.

One problem with high pressures, and you can experience with with clinchers if you want, is that you can experience tire hop. This is when your tire cannot conform to the road surface, but rather goes airborne over a bump (for a millisecond). When I was new to racing I would pump the hell out of my tires, thinking I would go faster. You can't ride confidently if you lose contact with the pavement (I am talking the rear hopping when hitting a bump while standing, accelerating out of a corner in a crit- or worse- the front hopping).

At 195 you can probably run higher pressures without hop-- but still, what are you really trying to accomplish? There is a law of diminishing returns with tire pressure... especially in real world (less than ideal) situations.

I am of the impression that max PSIs for tubular are more related to the specific tire than the rim, and far exceed realistic riding.



Bianco said:


> Bringing this thread back to life....
> a tubular's max psi can be 180+ is this correct? I am 195 pounds, so I'd think the more psi the better.
> What are the pros/cons of taking the psi that high?
> I know clincher rims have a max psi, not just the tire, but do tubular rims also have a max psi?
> Does anyone know what the tdf pros pump their tubies too? I usually run my Conti gp4000 clinchers to 125, but I'm thinking of switching to tubulars.


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## Yeomeo (Apr 5, 2007)

Save your tubs for racing and pump them up to 10-20psi less than their maximum to allow for increasing temperatures from friction _hardening them off_. Try to do the course ahead of time and see whether the road surface is good. If its bad let some more air out to prevent the _hop_.


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## filtersweep (Feb 4, 2004)

Yeomeo said:


> Save your tubs for racing and pump them up to 10-20psi less than their maximum to allow for increasing temperatures from friction _hardening them off_.


Friction from where? How much "friction" does it take to increase tire pressure. I am not buying it.

Finally, a Vittoria is rated at 115- 200 PSI. I don't even know how I would get your recommended 190PSI into them.


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## 52-16SS (Dec 16, 2002)

The only place heat from friction would be a problem is in heavy breaking, convection probably takes care of the heat from contact patch friction.


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## Bianco (Sep 22, 2004)

filtersweep said:


> At 195 you can probably run higher pressures without hop-- but still, what are you really trying to accomplish? There is a law of diminishing returns with tire pressure... especially in real world (less than ideal) situations.
> 
> I am of the impression that max PSIs for tubular are more related to the specific tire than the rim, and far exceed realistic riding.


Interesting. I hadnt heard of the diminishing returns regarding high pressure. I am among the misguided as described on the zipp site 
http://www.zipp.com/TabId/214/Default.aspx



> The problem is that high tire pressures feel fast as your body perceives all the high frequency vibrations from the road surface as being faster than a smooth ride.
> 
> Lennard Zinn had a great analogy when he said that 100kph in a Jeep will scare the crap out of you but 200kph in an S class Mercedes feels effortless...the same is true of bike tire pressures, but it's just hard to convince ourselves of that. As athletes we tend to buy into the 'if some is good, more must be better' philosophy, but this is rarely true. Of course the tire manufacturers have given up on this and continue to try and make higher pressure tires as that's what the consumers demand, as I think that they've decided that it is easier to just give people what they think they want than to try to educate and argue with them


I've always thought, and felt, that I could get a quicker acceleration with higher pressure. Plus, with my weight, I assumed I should go higher than "normal".


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## filtersweep (Feb 4, 2004)

Interesting article.



Bianco said:


> Interesting. I hadnt heard of the diminishing returns regarding high pressure. I am among the misguided as described on the zipp site
> http://www.zipp.com/TabId/214/Default.aspx
> 
> 
> ...


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## Yeomeo (Apr 5, 2007)

A mistake that many riders make (According to Greg LeMond and others) is to fully inflate your tyres. During this years Etape du Tour, Greg said that _there were an alarming number of blow-outs this year due to the friction against people's rims whilst braking._ He even stopped to let some air out so that he didn't have the same problem! If its good eneough for him, its good enough for me!


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## wim (Feb 28, 2005)

Yeomeo said:


> A mistake that many riders make (According to Greg LeMond and others) is to fully inflate your tyres. During this years Etape du Tour, Greg said that _there were an alarming number of blow-outs this year due to the friction against people's rims whilst braking._ He even stopped to let some air out so that he didn't have the same problem! If its good eneough for him, its good enough for me!


Something must have gotten lost in translation here. Heat generated by brake pad-to-rim friction on a long descent will heat the air in the tube to some degree. But there's not enough heat generated to cause an overpressure blow-out, even with the cold tube inflated to maximum recommended tire pressure. Letting air out of tire to prevent that which can't happen doesn't make sense.

What can happen is this: on long descents, brake pad-to-rim friction heats the rim and the tubular tire glue. The glue will soften as it gets hot and allows the tire to creep. If the tire creeps around the rim for too long, it can rip the valve out of the tube and blow out. The tire can also shift sideways on heat-softened glue and roll off the rim, which is much worse than losing a valve. Letting air out of a tire to prevent these two potential mishaps makes no sense either.


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## Yeomeo (Apr 5, 2007)

Sounds sensible........ was just quoting from Cycling Weekly (UK)
Ta


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## wim (Feb 28, 2005)

Yeomeo said:


> Sounds sensible........ was just quoting from Cycling Weekly (UK)
> Ta


Ah, the USA and the UK: two great nations separated by a common language . . . .


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## Mark McM (Jun 18, 2005)

*"tyres" at the "Etape du Tour" and brake heating*



Yeomeo said:


> A mistake that many riders make (According to Greg LeMond and others) is to fully inflate your tyres. During this years Etape du Tour, Greg said that _there were an alarming number of blow-outs this year due to the friction against people's rims whilst braking._ He even stopped to let some air out so that he didn't have the same problem! If its good eneough for him, its good enough for me!


Well, with a little better translation, it actually does make a little sense. Firstly, "tyres" is commonly used in england to refer to clinchers (tubulars are referred to as "tubs" or "sprints"). In addition, the Etape du Tour is more of a amateur randoneur type event, not a pro race, so it is likely that a much higher percentage of participants are using clinchers.

For clinchers, heat related blow-offs can be a problem on descents, as heat build-up from braking increases pressure increases as the air in the tires heats up. Lowering air pressure in clinchers on descents can be helpful in preventing brake-heat related blow-offs.


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## DIRT BOY (Aug 22, 2002)

Keeping up with Junior said:


> Just slapped some Conti Comps (22) on my Reflex rims and curious what pressure folks would recommend running. Raced on them at 120psi last weekend and was happy, not too soft but not too hard. Just looking which direction to experiment until I settle on a happy psi number.
> 
> Looking for use in road races on good surfaces. I am 160# and on my training wheels run Michelin Pro Race at 110psi. Previously running Tufo HICC at 125psi, definitely find the Conti's feel better and a bit more confident cornering.


I am running 100/110 on on Corsa CX tires. I am 165lbs.


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## wim (Feb 28, 2005)

> _Well, with a little better translation, it actually does make a little sense. Firstly, "tyres" is commonly used in england to refer to clinchers (tubulars are referred to as "tubs" or "sprints")_


Thanks, my brain was locked onto tubulars. Clinchers _can_ lift off the rim if their bead gets hot from long, hard braking, softens and squirms past the rim's bead hook. Lemond and Yeomeo got it right.


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## Forrest Root (Dec 22, 2006)

I weigh in at, unfortunately, about 178lbs right now. My 23c clinchers are inflated to 105 psi front and 110 psi rear. My 22mm wide Vittoria tubies are inflated to 100 psi front and 105 rear. In the rain or in the cold, I put fewer Nitrogen, Oxygen, Carbon Dioxide, Carbon Monoxide, and if I've over beaned, Methane molecules in my tires than I normally do.


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