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Thread: Cross pressure

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    Senior Member Plow13's Avatar
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    Cross pressure

    im a good old fat boy in the sport of cycling...i weigh 206...what kind of tire pressure should i be running? just a ballpark figure be awesome...im just not too sure where to start
    Cervelo S1 2010 (road) Lemond Alpe d'Huez 2004 (road)
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    depends on the course and depends on what type of tire and set up you have, tubular, tubeless, or clinchers
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    Senior Member Plow13's Avatar
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    i have clinchers
    Cervelo S1 2010 (road) Lemond Alpe d'Huez 2004 (road)
    Trek 4500 2006 (mtb) Gary Fischer Utopia 2008 (commuter)
    Redline Conquest 2009 (cross) Redline 925 2009 (single speed)

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    Quote Originally Posted by Plow13 View Post
    i have clinchers
    what tire is it and what width?

    one good method is to start at the highest PSI for you tires, probably around 65psi, and then drop in 5psi increments until you pinch flat, then add 5 psi to your final number.
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    Senior Member c_m_shooter's Avatar
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    I normally run around 45-50 psi. Others claim to run lower, but I can't avoid pinch flats below 40 psi in 35mm tires.
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    Oh The Huge Manatee Lithuania's Avatar
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    run it low enough so that you bottom out like once per lap.

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    Remember to chalk/talc your tires and tubes to avoid pinch flats.
    I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC

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    Anything less than 14.2 psi. That wa the tubes benefit from osmosis of atmospheric pressure, and gain pressure rather than lose it. It also gives you the added benefit of reducing the wear on rims and components...

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    Quote Originally Posted by Lithuania View Post
    run it low enough so that you bottom out like once per lap.
    Isnt that the rule of thumb for tubulars?
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    Oh The Huge Manatee Lithuania's Avatar
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    hmmm i cant remember if that was tubular only. you might be right about that though.

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    Quote Originally Posted by Lithuania View Post
    hmmm i cant remember if that was tubular only. you might be right about that though.
    I think it is, because if you bottom out a clincher you will almost surely get a pinch flat.
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    I run at around 35-40 PSI, which is 5-10 PSI below the recommended minimum on my Maxxis Locust CX tires (clinchers), and I haven't had a pinch yet, so I've been thinking about going lower. I weigh 185 now, but I weighed around 200 last season and I used the same pressure.

    The courses I've ridden have been pretty soft. If I had any rocky sections or drops to deal with I'd probably go with a higher pressure.

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    I think this is something you need to test out. Expensive test though because you could go through many tubes. I am safe running 40psi with my Maxxis Raze's and I am about 150lbs.

    What is this chalk/talc thing about? I have never heard of doing this.

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    Quote Originally Posted by hocker View Post

    What is this chalk/talc thing about? I have never heard of doing this.
    talc your tubes so that the tube can slide more freely underneath the tire. I dont know if it cuts down on pinch flats, but it should lower your rolling resistance and makes changing tubes easier as they wont adhere to the casing.
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    During last weeks race I was bottoming out several times on the rear and it was quite squirley in the corners. I didn't pinch flat and that was on a clincher. I'm sure that the talc job saved me from a DNF.
    I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC

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    [QUOTE=jonestr;9700363]talc your tubes so that the tube can slide more freely underneath the tire. I dont know if it cuts down on pinch flats, but it should lower your rolling resistance /QUOTE]

    Myth.

    http://yarchive.net/bike/tire_talc.html

    In the days before tubeless tires on cars, automotive tubes that were
    not much thicker than the heavier bicycle tubes vulcanized into the
    tire from the heat of the road and would rip when forcefully removed.
    For this purpose, talcum was extensively used. Bicycles don't have
    enough power not enough rolling resistance to generate vulcanizing
    temperatures required to cause such adhesion so using talc has little
    purpose. You'll notice that tubes contain talcum, and that is for the
    purpose of preventing adhesion in the package of two absolutely clean
    surfaces. You don't have that problem. In fact, adhesion of the tube
    to the casing prevents rapid air escape in the event of a thorn
    penetration.

    Talcum, like tying and soldering, will last as much as 40 years after
    the last need for it vanished. The last need for tying spokes
    together at their crossings vanished with high wheeled bicycles that
    threw the rider if a spoke broke and lashed about freely. Talcum in a
    bicycle tire never had a reason, it has always been done in imitation
    of automobiles, but even they don't use it anymore.

    Jobst Brandt
    Brandt designed tyres - the very successful Avocet Fasgrip was his work.

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    You may want to play with the psi on your tires a bit. I am 195lbs and I run my tubulars from 30-40 and my clinchers from 35-45.

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    [QUOTE=meanwhile;9700404]
    Quote Originally Posted by jonestr View Post
    talc your tubes so that the tube can slide more freely underneath the tire. I dont know if it cuts down on pinch flats, but it should lower your rolling resistance /QUOTE]

    Myth.



    Brandt designed tyres - the very successful Avocet Fasgrip was his work.
    Whatever the method, every untalced tube I have had has formed a bond with the tire. Work in a bike shop for 10 years and you will find this phenomenon quite often.
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    [QUOTE=meanwhile;9700404]
    Quote Originally Posted by jonestr View Post
    Brandt designed tyres - the very successful Avocet Fasgrip was his work.
    Bike Snob NYC readers are, of course, familiar with Brandt.


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    I normally ride in the 35psi range on grass/soft.. 40 or so on hard packed.. 40 will still bottom out on square faced bumps at speed.. so pick lines carefully and get weight off as needed. (i hit rim twice last week, luckily no pinch flats)

    I'm 185#, 35c tires.
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    I weigh 130 lbs and with my new tubluars I am running 60 psi now. Rolls great but doesnt grip as well. I think i'll lower them to about 50 psi.

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    Quote Originally Posted by jonestr View Post
    I think it is, because if you bottom out a clincher you will almost surely get a pinch flat.
    I think it depends on the tire/tube/rim/rim tape combo.

    I was running my tires (30's) at like 35 psi and I could push down on the tire and see it bottom out, but nothing happened.

    It's insane how critical psi is in this game.
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    Quote Originally Posted by ridethecliche View Post
    I think it depends on the tire/tube/rim/rim tape combo.

    I was running my tires (30's) at like 35 psi and I could push down on the tire and see it bottom out, but nothing happened.

    It's insane how critical psi is in this game.
    Unless you are on an ultra soft course I would be extremely wary of running that low of a pressure on a clincher
    For Sale:
    Dugast Rhino 30c, previously glued and needs new tube, but lots of tread left $35+ shipping

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    Quote Originally Posted by jonestr View Post
    Isnt that the rule of thumb for tubulars?
    yeah it is. Also with tubulars you should be able to touch the rim with a lot of force pushing down on the tire with your thumbs.

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