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  1. #1
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    Tire Pressure

    I was running really high air preasure around 50 to 60 psi I was imformed I should be running about 35 psi. Thoughts, Suggestions........

    Thanks

  2. #2
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    Run as low as you can go without pinch flatting (hitting rim).

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    Quote Originally Posted by kjames80
    I was running really high air preasure around 50 to 60 psi I was imformed I should be running about 35 psi. Thoughts, Suggestions........

    Thanks
    35 psi is a good start but even with tubes (I am guessing you are running tubes...) you can run quite a bit lower pressure than 35psi depending on your ride style, trails, tires, bike, etc... Some tires react better to lower pressure than others but depending wholly on the tires tread and not letting the carcass conform to the ground reduces the grip and rolling resistance (not intuitive compared to car tires that heat up and offer too much rolling resistance if too low on air) bla bla bla...

    Start at 35 psi and release 1-2 psi on a familiar trail and ride to see how it feels, repeat and keep testing to see what feels best- there is no mysterious perfect psi for all applications-
    I Just wish I could ride more!


  4. #4
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    Full suspension geared, I run about 24-26 front and 27-30 rear.

    Single speed rigid, I run 18-21 front and 23-26 rear.

    edit: I run tubeless, no pinch flats, or any flats, actually. YMMV
    Last edited by slocaus; 01-31-2010 at 09:33 PM.
    "The physician heals, Nature makes well" - real fortune cookie

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  5. #5
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    Tire pressure is a funny thing - kinda like trying to ride a skateboard on a titerope. Too much and you are going to have no traction and wash out your front wheel. Too little and you pinch flat. My suggestions is to document your process so you know where your sweet spot is.

    My sweet spot seems to be at 30psi front and rear. I generally ride 10-15 miles of road to the trailhead and this gives me enough pressure to keep some momentum on the road and some squish on the dirt. That said - I pinch flatted in 18 degree weather this morning.

  6. #6
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    For me at 175 LBS it's 22 in the rear and 20 in the front - Tubeless.

  7. #7
    Noli Me Tangere
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    I weigh about 220 with riding gear and still run tubes on my Monocog with Exiwolf's and roll with 32-33 front and rear. No pinch flats or flats (I use Slime tubes) either.
    Annie are you ok? Are you ok, Annie?

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    220 Geared up riding a lot of roots,

    On Flows and Blunts, they both are 28mm wide:
    I believe that the wider the rim, the lower you can go with the pressure.

    With tubes: 30 front and rear, one pinch flat ever, on the rear with a Nanoraptor after nailing a big root, I didn't bother checking the pressure, and am sure it was probably around 27 or so.

    Tubeless: Front 25/26 Rear 27/28. (I did burp said Nanoraptor once below 30 tubeless before)

  9. #9
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    Riding weight 155lbs

    Rocky Terrain (Arizona): 26 front, 28 rear
    Hardpack / Some Roots and Rocks (Ohio): 24 front, 26 rear

  10. #10
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    Wow, I have been running way too high pressure for years!! Question, does this hold true for FS bikes in addition to hardtails?

  11. #11
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    Just experiment with it. Drop and raise your pressure on rides, see how it changes things. Bring a pump with you and raise your tire pressure if you start bottoming out (not good for your rim!!)

  12. #12
    Fat and Slow
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    i also ride my bike on the road pretty often,,,,, SO,,,,,if i am road riding, my tires are maxed out - 80psi. on the trail, i usually have 35psi.
    09 Hardrock Sport Disc.

  13. #13
    the mountian is within
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    WOW!! Im 250 and run 35r-25f
    2.4 Mtn King rear
    2.4 Ardent front
    with tubes!
    Fully rigid-WV rocks and roots!
    Go as low as you can-it is more traction and cush...
    i own a bikeshop in WV thetruewheelwv.com

  14. #14
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    Quote Originally Posted by chrisreilly
    Wow, I have been running way too high pressure for years!! Question, does this hold true for FS bikes in addition to hardtails?
    Yes it does. Lower pressures create less rolling resistance (which will make you faster) while providing much better traction. You should always run the lowest pressure you can while on a MTB without pinch flatting (for tubes) or bottoming out (rim hitting objects on trail). On a road bike higher pressures are faster and better because the surface is smooth. For a good explanation of rolling resistance check out this pdf:

    http://www.bicicletta.co.za/Download...llustrated.pdf

  15. #15
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    I'm close to 200 lbs geared up, and run about 23 f / 27 rear on my rigid 29'er. 2.2 or 2.3 tires. I have a 2.0 on the rear right now for winter mud, and it is closer to 30 psi with the smaller volume. On occassion I will bottome the rim and tire, but running tubeless, no problemo. Even 35 sounds really high - at 50 it must be like riding a billiard ball on the trail!
    R.I.P. Corky 10/97-4/09
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  16. #16
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    Quote Originally Posted by MallardMauler
    i also ride my bike on the road pretty often,,,,, SO,,,,,if i am road riding, my tires are maxed out - 80psi. on the trail, i usually have 35psi.
    Wow! I don't think I've seen too many mountain bike tires that are even certified to run at 80psi.

    Ronnie.
    The trouble with having an open mind is that people will insist on trying to put things in it.

  17. #17
    SyT
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    Quote Originally Posted by EthanDM
    . You should always run the lowest pressure you can while on a MTB without pinch flatting (for tubes) or bottoming out (rim hitting objects on trail).
    http://www.bicicletta.co.za/Download...llustrated.pdf
    I don't buy into this at all because it leaves out the fact that you can run a tire just
    high enough to avoid pinching and the thing may wallow like crazy in the corners because the tire isn't stiff enough to avoid folding over. RR 2.4 are notorious for this in my experience.

  18. #18
    recognize the slowness
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    I just run enough to not bottom out on roots etc.....I hate that sound!!!

    approx 30psi rear and 25 is in the front. If I need to add I do. As always YMMV.
    "mountain biking and flyfishing, what more do you want?" - Yeah, I said it

  19. #19
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    I had much rather deal with a bit of frontend push than pinch flats, so I usually run 40 or so. That way too, if I grab the bike a week or so later, I don't have to adjust it, I know it still has enough air. I think it does have alot to do with how you are riding and what you weigh. I weigh 250 or so, or else I would try and get away with a lower pressure.

  20. #20
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    I'm about 200 lbs with gear.

    I run 19-20 psi front & rear on Racing Ralphs 2.4 with Flow rims on Niner EMD HT. In 4 seasons I've had only 1 flat and it was because the sealant dried up. I added sealant and kept using the same tire for another 6 months.

    Not only does low pressures improve comfort/control/traction, I feel tires become more resistant to tears & punctures because it folds around sharp objects rather than resist.
    www.ottawavelo.com - MTB & Gravel lifestyle in Eastern Ontario

  21. #21
    SyT
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    Quote Originally Posted by fritZman
    I'm about 200 lbs with gear.

    I run 19-20 psi front & rear on Racing Ralphs 2.4 with Flow rims on Niner EMD HT. In 4 seasons I've had only 1 flat and it was because the sealant dried up. I added sealant and kept using the same tire for another 6 months.

    Not only does low pressures improve comfort/control/traction, I feel tires become more resistant to tears & punctures because it folds around sharp objects rather than resist.
    I can't imagine the type of riding or the (off road) terrain in which you're able to do this. I 'm about the same weight, maybe a few pounds less depending on what day it is, not only would I not be able keep the rims in their intended shape, that tire would fold over in any near aggressive cornering scenario. I had that tire on Gordo and anything under 25psi was asking for problems.
    Having said all that, I don't get 6 months (or more) out of a tire either, so clearly we have very different situations going on.

  22. #22
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    Quote Originally Posted by SyT
    I don't buy into this at all because it leaves out the fact that you can run a tire just high enough to avoid pinching and the thing may wallow like crazy in the corners because the tire isn't stiff enough to avoid folding over.
    I agree, and I'm running a tubeless set-up with Flows. I hate when I'm throwing the bike around and can feel a tire wallow (especially the front tire). What is the point of building up a stiff frame/fork/wheel, and then running tires so low that they're wallowing?

    Also, since I run single speed, I don't want the rear too low, or it makes sudden accelerations (especially when standing) feel less responsive than they it could be.

  23. #23
    trail rat
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    Some of us ride 'lighter" than others (not a value judgment, just an observation). I started on rigid MTBs back in 1979; pinch flatted a gazillion times, and bent many rims. You learn to lift and pre-jump, subtlely, if that makes sense. Those habits followed me into suspension bikes, and since I still ride a rigid SS, I keep them honed.

    On low pressures in tires, I feel the lower rolling resistance, and the tire tread compliance to the ground. Hard tires to me feel like steel tires with no tread on slick rock. To each his own, viva la difference. Works for you, works for me.
    "The physician heals, Nature makes well" - real fortune cookie

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  24. #24
    SyT
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    Quote Originally Posted by slocaus
    Some of us ride 'lighter" than others (not a value judgment, just an observation). I started on rigid MTBs back in 1979; pinch flatted a gazillion times, and bent many rims. You learn to lift and pre-jump, subtlely, if that makes sense. Those habits followed me into suspension bikes, and since I still ride a rigid SS, I keep them honed.

    On low pressures in tires, I feel the lower rolling resistance, and the tire tread compliance to the ground. Hard tires to me feel like steel tires with no tread on slick rock. To each his own, viva la difference. Works for you, works for me.

    If this is in reference to my post, it should be noted that, aside from a Giant STP, every bike I own is rigid (and single speed)

  25. #25
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    Rampage 2.35" front and rear tubeless on Flow rims
    32 rear 30 front
    I ride as much roots / rocks / gnar as I can, mellower stuff too. Like to go fast.
    Unseated a front tire at speed on a root at night running around 28psi, superman over the handlebars. So that's too low.

    Morgan

  26. #26
    trail rat
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    Quote Originally Posted by SyT
    If this is in reference to my post, it should be noted that, aside from a Giant STP, every bike I own is rigid (and single speed)
    Not aimed at anyone, just noting the differences of opinion of what we like in tire pressures.
    "The physician heals, Nature makes well" - real fortune cookie

    CCCMB trail work for trail access - SLO, CA

  27. #27
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    Quote Originally Posted by SyT
    I can't imagine the type of riding or the (off road) terrain in which you're able to do this.
    I am about 190lbs too and run a set of Kenda Nevegals with 20psi front and rear tubeless on WTB trail discs with not problems. In the past with tubes I had to be at least at 30psi to avoid pinch flats.

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