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Discussion Starter · #1 ·
OK, i have been playing around with tire pressures, and am getting some mixed results, this is what i have:

I weigh 220lbs

running Vittoria XG Pro's

When i have lower pressure 30-35lbs i feel like the rear end is washing or sliding out, feels "loose"

when i run 45-50lbs the rear end feels much more planted, not much washing or sliding feeling.

since i live in the Northeast, obviously it has been dry and the ground is hard, do you also change your tire pressure depending on condition?? I would imagine so, i would guess more pressure for dry fast and less for mud etc.

Should I be running more pressure cause i am on the heavier side?

thanks for your help
 

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Obviously, weight has a lot to do with what pressures are appropriate. I run low-30s, but I'm 145lbs. I've experimented with higher pressures but unless the hardpack is real smooth I find I get bounced around enough that the higher pressures don't make me faster.
 

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I'm also a lightweight at 140 lbs, and typically run in the 25-28 psi range. Certainly 30 psi or so seems low for anyone 200lbs+, at least to me.

I get that washing out feeling on some of my MTB tires below 20 psi, and it mainly seems to be due to the tire rolling or folding when cornering. A little more pressure usually solves the trick.

In terms of setting pressure, I typically make a guess (usually high) and do a practice lap. Adjust, repeat until course feels smooth but not too sketchy (and I'm not bumping rims on every rut/root).
 

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I typically run my Tubs

from 35-45 psi and I'm 220 plus
 

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Some of this discussion comes back to tire width/rim width. You could get away with lower psi without the rolling feeling with a wider rim/narrower tire. I've found with cross and mtbing that I prefer a slightly narrower rim given the tire width that I'm using- I think the tire profile gives better feedback when cornering and into transitions.

I'm about 200 and usually I try to find the right mix of softness. I have a set of 35mm tires that get kinda spongy if I stand and climb (SS) if they go below 50psi, but the 30mm can go a little lower without the same feel.
 

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What do people do if you don't have Tubulars. I'm a new racer this year and ride with clinchers. I'm concerned if I drop the pressure too much I'll get pinch flats.
 

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You'll need to run higher pressures. I have Tufo tubie clinchers on my back up bike and run around 40 in the rear and 38 or so up front. Real clinchers you'd want to go a bit higher. My tubies I run around 35 rear and 32 or so up front and I weigh 180. That combo hooked up nicely this weekend on the hard packed grass crit of Nittany Lion cross.
 

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Unless they're racing really fast courses with big potholes or something, I think most people will be able to run 32-35lbs on clinchers.
 

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well before I had tubulars

iherald said:
What do people do if you don't have Tubulars. I'm a new racer this year and ride with clinchers. I'm concerned if I drop the pressure too much I'll get pinch flats.
I ran clinchers at such high psi they handled like crap

when I lowered the psi I'd pinch flat

why I run tubs
 

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I run my clinchers, Grifo open tubulars at 32 front and 35 rear for training.
I run my tubulars Vittoria high TPI versions at 24-26 front and 26-28 rear depending on the conditions and terrain.
I weigh 160lbs and race in BC.
It took some getting used to because the rear is a bit squirmy, especially on pavement, but I can roll into a corner so much better and I do not get bounced around so much in the long straight bumpy grass sections.
 

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Thom H
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THE GUY WEIGHS 100KG. He does not need any advice from a 70kg rider on air pressure they use. I weigh 92kg and have been riding cross clinchers and tubies for 30 years. 40lbs is a good starting point. Plus or minus 5 might work but starting at 40 will get him in the game. But people are full of crap if they think a 100kg rider can run 32lbs and not pinch or destroy his rims, expecially a relatively new guy.
I ride light for my weight and still hit bottom way too hard once or twice a year in the 38-40 range on big 34s, On a smooth couse with my FMBs I might go 35 ish, but not only do the tires hook up better at lower pressures, the sidewalls sometimes get real squirrly and try to roll under too. For a beginner that can get unnerveing as well. You do need to learn to trust your tires, but you also have to help them with the right air pressure.
You lightweights can rail all you like on my post, but you will not change my personal experience on air pressure for the big boys.
 

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Take it easy buddy, Rudedog55 is not the only one asking questions about tire pressure on this forum or this thread.
 

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Thom H
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I am not angry and don't need to take it easy, but it is plain nuts to try and compare tire pressures needed for a 60 kg rider and a 100kg rider in the same thread. The original post says I weigh 220 so I am thinking we are only talking about a 100kg rider. My apologies if any one was offended.
Bunch of the other guys around two bucks all agree that the tires get real silly at lower pressures. My rule of thumb is to start out at 40 and let air out till they get goofy and add back a couple lbs. You would not believe how many people ask about tire pressures or squeeze my tires and tell me they are too hard. We aren't even in the same area code with three to five bowling balls worth of cargo strapped on the same bike campared to a 65kg rider..
 

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Thom H said:
THE GUY WEIGHS 100KG. He does not need any advice from a 70kg rider on air pressure they use. I weigh 92kg and have been riding cross clinchers and tubies for 30 years. 40lbs is a good starting point. Plus or minus 5 might work but starting at 40 will get him in the game. But people are full of crap if they think a 100kg rider can run 32lbs and not pinch or destroy his rims, expecially a relatively new guy.
I ride light for my weight and still hit bottom way too hard once or twice a year in the 38-40 range on big 34s, On a smooth couse with my FMBs I might go 35 ish, but not only do the tires hook up better at lower pressures, the sidewalls sometimes get real squirrly and try to roll under too. For a beginner that can get unnerveing as well. You do need to learn to trust your tires, but you also have to help them with the right air pressure.
You lightweights can rail all you like on my post, but you will not change my personal experience on air pressure for the big boys.
I run my tuulars soft enough so that I bottom them once a lap! That clearly won't fly with clinchers, but with tubulars the key seems to be able to learn to ride them so they do feel like they are folding on you when you hit pavement.
 

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Discussion Starter · #17 ·
thanks for the replies, as i play around more and learn, i am seeing a serious decline in handling sub 40lbs for me, my bike and i seem to be around 44-46lbs to be grippy and not washy. The thing is there is so much reading material regarding these type of subjects, and more than often you read about super low pressures like sub 30, and i am sure they work for some riders, it did not work for me, so i asked the question, and yet a lot of people do not take rider weight into consideration. The front tire really not an issue and i am loading the rear more than the front, so i can run that a little softer up there. I am no expert by any means, but i would like to think i have some bike handling skill, but learn every time i practice or race....now to get sub 100kg, lol. But i appreciate all the replies none the less.
 

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Thom H
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Glad to help confirm what the other big boys are doing. Word of advice. Don't take up hillclimbing. Being big is bad enough on the flats, verticle it really sucks. I have noticed being bigger in cross you don't get bumped as much as the smaller fellas in the corners.
 

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Mine..

First let me state my actual racing weight is just under 180 in my skivies....

Tubies for racin' - what that other dude said about enough pressure so you bottom out 1x per lap. (i.e 27-31 psi, course dependent, no exceptions except if you weight more or less than me. then you can go +/- 3psi). This is a strict rule. Tubulars, while only allowed for racing, must also be narrower than your clincher training set by at least 2 mm, preferably more.

Clinchers for training only (racing only if you flat during a race with tubies) - MUST be run at higher pressures than your tubulars.... about 5-7 lbs/sq.in no more, no less. Again, a strict rule that must be followed at all times.
 
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