What pressure for tubs in TT's ?
andy_wrx
Posts: 3,396
I've just got some Cosmic Carbones and fitted Conti Podium 19mm tubs to them.
Conti's diagrammatic fitting instructions sheet says 145psi, but I'm not sure if that's simply the pressure they're saying to inflate them to while the glue sets or is the pressure they're recommending you ride them at.
Certainly there's no table suggesting pressure you should run them at vs. your weight, etc like you get on the back of a Michelin packet, and I can't find anything on Conti's website either.
I did a Cheshire TT at the weekend and they felt great on the smooth sections but were bumpy as hell on on the not-smooth sections, so much so that they loosened the headset !
I guess it's a trade-off between rolling resistance, grip, comfort, etc but what pressures do people use ?
- I'm ca 72kg and had no grip/sliding issues but probably lost a tiny little bit of time as I eased-off over the very bumpy bits.
Conti's diagrammatic fitting instructions sheet says 145psi, but I'm not sure if that's simply the pressure they're saying to inflate them to while the glue sets or is the pressure they're recommending you ride them at.
Certainly there's no table suggesting pressure you should run them at vs. your weight, etc like you get on the back of a Michelin packet, and I can't find anything on Conti's website either.
I did a Cheshire TT at the weekend and they felt great on the smooth sections but were bumpy as hell on on the not-smooth sections, so much so that they loosened the headset !
I guess it's a trade-off between rolling resistance, grip, comfort, etc but what pressures do people use ?
- I'm ca 72kg and had no grip/sliding issues but probably lost a tiny little bit of time as I eased-off over the very bumpy bits.
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Comments
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I think 145 is way too much - as you say - you're bumping all over the place. Its probably going to be trial and error. I run 90-95 in tyres and about 110 in my Conti tubs.0
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cougie wrote:I think 145 is way too much - as you say - you're bumping all over the place. Its probably going to be trial and error. I run 90-95 in tyres and about 110 in my Conti tubs.
I run mine at 140. They are rated up to 220 I think!
I find anything under 120 way too spongy. And have never 'bounced around' on rough road. But I'm also kinda fat.
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I weigh in around the same as you and run my tubs at around 120 on the back and 110-115 psi on the front, When I first started using them for racing a few years back, I did what you have done and ran them at high pressure. No need to.0
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A variety of opinions then
I s'pose I can have a trial on the Weds night club events - let em down a bit and see what difference it makes
- trying it in training won't work, I never go hard enough unless someone's waving a watch at me
thanks0 -
140+
dont be afraid to put more in
they can easily handle it
the more air, the less rolling resistance
19mm tyres require much more pressure than say 23mm
the 110 - 120 psi is way too low for you to get the most out of your tyres0 -
I just want to know where this smooth bit of TT road is in Cheshire?!!0
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a_n_t wrote:I just want to know where this smooth bit of TT road is in Cheshire?!!
There's a short bit on our club 10 of about 80 metres. To be fair, our 10 is on one of the smoother stretches out there despite still having some sharp edged bomb holes.
You wouldn't have seen the smooth bit because you went the wrong way!0 -
I use about 130 psi, at 73kg. You don't want them too hard, as although you may not feel it, they will bounce across the imperfections of the road, rather than absorb them, and you might go slower.
Probably doesn't make a huge amount of difference in the grand scheme of things. I guess trial and error to what you think is best for you, and the condition of the course.0 -
NapoleonD wrote:You wouldn't have seen the smooth bit because you went the wrong way!
Actually, thinking about it, J2/1 isnt too bad.0 -
I never made it
The nipper was up every 2 hours on friday night then decided to wake up at 5am. not the best prep for a 25 so I didn't go.0 -
Not sure thats true. The british squads did testing and found that for increased air pressure rolling resistance actually increased and that was carried out indoors on lovely smooth wooden tracktri-sexual wrote:140+
dont be afraid to put more in
they can easily handle it
the more air, the less rolling resistance
19mm tyres require much more pressure than say 23mm
the 110 - 120 psi is way too low for you to get the most out of your tyres 0 -
SBezza wrote:I use about 130 psi, at 73kg. You don't want them too hard, as although you may not feel it, they will bounce across the imperfections of the road, rather than absorb them, and you might go slower.
Probably doesn't make a huge amount of difference in the grand scheme of things. I guess trial and error to what you think is best for you, and the condition of the course.
+1
I'm 90kg and use 140 psi on same wheels but with fortezza tricomps. I used to race at around 90 psi - the difference is tangible, go as hard you feel comfortable with.0 -
oldwelshman wrote:
Not sure thats true. The british squads did testing and found that for increased air pressure rolling resistance actually increased and that was carried out indoors on lovely smooth wooden tracktri-sexual wrote:140+
dont be afraid to put more in
they can easily handle it
the more air, the less rolling resistance
19mm tyres require much more pressure than say 23mm
the 110 - 120 psi is way too low for you to get the most out of your tyres
+1
I also understand the rolling resistance of a tub can be significantly affected by how well you do or don't glue it on the rim. I have about 120 psi in my rear tub on Cheshire, which personally I think helps cope with the bobbly surface instead of just bouncing on it. I weigh around 76 Kgs0 -
I used to put about 160 psi when I raced on tubs years ago.0
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Depends on a few factors :
Rider weight
Road surface
Dry/wet
Decent dry roads for my 70kgs I'd put 120psi, super smooth maybe 15psi more, wet a touch less, rough also less : this being 110 or so.
Harder feels 'zingier' but if the road is rough then you are bouncing vertically as opposed to the tyre deforming to the road surface and helping provide forward motion.
I spoke to HED after having problems with my Stinger's (smaked potholes really hard and cracked rim - not a product fault), and they said that at the TdF they'd experienced tubs being inflated to 110psi or so - Tdf riders are obviously very light so that will have an influence but 150+psi on our roads is excessive.0
