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  1. #1
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    Tire pressure for all around XC riding?

    I was curious to know what tire pressure is the best for all around xc use?
    I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
    I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
    Any suggestions would be great. Thanks

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    i run 40psi on 2.00 tires on my rigid
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    As low as possible. I'd start at the lowest recommended pressure (as printed on the tire) and see if you get a pinch flat (small holes on both sides of tube where it contacts the rim). If so, put in a few more psi and run that. If you don't get a pinch flat, run a few psi lower until you do pinch flat.

    Tire pressure is an individual thing. You may also play with the pressure to see how it effects handling, traction, and rolling-resistence.

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    How much do you weigh? A 140 lb. rider can get away with much lower psi than a 210 lb. rider .

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    Quote Originally Posted by Lugi
    I was curious to know what tire pressure is the best for all around xc use?
    I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
    I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
    Any suggestions would be great. Thanks
    You have to experiment. Keep dropping the pressure until you start getting pinch flats or the tires feel squirmy in the corners, then add 2-3 psi. This will be where most tires will preform the best, though a few models may have a sweet spot that is a little higher depending on riding style and terrain.
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    I'm a big fan of lower pressures. I generally run about 22-23 on my 2.3-2.4 tires, 24-25 on 2.1's. I weigh 160 and ride rocky and rooty trails, but the rocks around here tend to not have sharp edges. I will add a couple psi if I expect to be riding somewhere with sharper rocks. My trails also tend to be a lot of slow technical riding, so the low pressure really pays off. If I expect to ride somewhere with higher speed turns, I will up the pressure a little to avoid that squirmy feeling Shiggy mentioned (it can be real unnerving). I am running tubes (not tubeless).

    Also be aware that I have yet to find 2 tire pressure gauges that give the same reading, so my psi listings are relative to my main tire gauge.
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    Quote Originally Posted by trailville
    I'm a big fan of lower pressures. I generally run about 22-23 on my 2.3-2.4 tires, 24-25 on 2.1's. I weigh 160 and ride rocky and rooty trails, but the rocks around here tend to not have sharp edges. I will add a couple psi if I expect to be riding somewhere with sharper rocks. My trails also tend to be a lot of slow technical riding, so the low pressure really pays off. If I expect to ride somewhere with higher speed turns, I will up the pressure a little to avoid that squirmy feeling Shiggy mentioned (it can be real unnerving). I am running tubes (not tubeless).

    Also be aware that I have yet to find 2 tire pressure gauges that give the same reading, so my psi listings are relative to my main tire gauge.
    22psi? isnt that kinda low? whats your tire look like while riding.
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    Quote Originally Posted by Spawne32
    22psi? isnt that kinda low? whats your tire look like while riding.
    Evidently, not for him. I rarely have more than 30psi (usually less) in any of my tires and I outweigh trailville by at least 20 pounds.

    I do not look at my tires while riding.
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    Quote Originally Posted by shiggy
    Evidently, not for him. I rarely have more than 30psi (usually less) in any of my tires and I outweigh trailville by at least 20 pounds.

    I do not look at my tires while riding.
    i mean like when weight is on it, i would figure 20psi on that size tire would be almost flat
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  10. #10
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    Drop psi until you get pinch flats. Every one and every ride is different. If you ride slow and/or easy, you can get away with very low pressures. However, I'm only 140lbs, but can't drop the rear below 35 psi or I will pinch flat when pounding over rough trails.

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    i am always somewhat confused about what pressures to run for trail riding, but what seems to "feel" best to me (i weight about 170lbs with gear) is 28 psi front, and 36 psi rear on maxxis high roller 2.35 single ply's, give or take a very few psi. any more on the front and it feels sketchy, less and i feel the rim getting tagged on bigger rocks. on the rear, less than 36 and it feels like the bike won't roll fast enough (and rim gets tagged), more and i can feel the back skipping over too much stuff, braking is bad, and too much boot-boot. i tend to try to run as much pressure as i can get away with though, because i have more fun riding when the bike rolls faster - this is for general trail riding. but for bike parks i run 2.5 maxxis 2-ply dh tires with 27 psi front, and 35 rear, exactly. for dirt jumps i run 40 psi front, and 50 psi rear for railing berms at high g's - although this can vary more since you don't have to deal with terrain on flow trails.

    why more in back than front? because i DO look at my tires while i ride! one of the things i do when testing a different tire pressure is do a "tire sag" check - i sit on the bike and look at the tire to see how much it bulges at a certain psi. i can't explain here how to judge this, but keep in mind that a tire works best on a certain size of contact patch that will vary with psi, tread design, rider weight, casing design, tire size, rider weight distribution, riding style, dynamic forces while riding, and other factors. as part of my riding style, i try to keep the front end light as often as i can by keeping my weight on the pedals (not on my hands), and when riding faster and more aggressive (which i do as often as possible) the weight distribution shifts more rearward. add to this that the weight distribution on my bike is already 40/60 front-to-rear. so, the weight distribution calls for more pressure in the rear and less in the front to keep things balanced-out.
    Last edited by mr.niles; 10-06-2009 at 11:58 PM.

  12. #12
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    I'm 143lbs, riding 24f/28r on 26x2.0" at the moment.

    The rear is a bit skinny for a 2.0; when I get a true 2.0, I'll drop the pressure to 26ish.

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    Quote Originally Posted by mr.niles
    i am always somewhat confused about what pressures to run for trail riding, but what seems to "feel" best to me (i weight about 170lbs with gear) is 28 psi front, and 36 psi rear on maxxis high roller 2.35 single ply's, give or take a very few psi. any more on the front and it feels sketchy, less and i feel the rim getting tagged on bigger rocks. on the rear, less than 36 and it feels like the bike won't roll fast enough (and rim gets tagged), more and i can feel the back skipping over too much stuff, braking is bad, and too much boot-boot. i tend to try to run as much pressure as i can get away with though, because i have more fun riding when the bike rolls faster - this is for general trail riding. but for bike parks i run 2.5 maxxis 2-ply dh tires with 27 psi front, and 35 rear, exactly. for dirt jumps i run 40 psi front, and 50 psi rear for railing berms at high g's.
    Some time you should actually put a clock (or GPS) on your runs and see how different pressures affect your speeds.

    I have done this with a Garmin Edge GPS when testing tires. The runs that felt the fastest were many times the slowest. They where exciting and it seemed I was going into the corners at a higher speed but in reality the tires where just bouncing and sliding more and harder to control. Slower into the turn and slower yet coming out of them. Heck, the higher pressure runs where even slower on the climbs.

    That is not to say the faster, low pressure runs were more fun. There was a lot less drama in covering the lap. Definitely not as thrilling a ride.
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  14. #14
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    Quote Originally Posted by Spawne32
    i mean like when weight is on it, i would figure 20psi on that size tire would be almost flat
    The point is if you are not bottoming out the tire, it does not matter. 22psi in 2.3-2.4" tires is not unusual or "look" low (if you could see it).
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    well im about 165 pounds and 40 psi in the rear is usually where i feel comfortable, adding a bit more flex to the front tire might make it a little easier on my arms but i dont know how much more difficult it would be to accel the bike forward with lower tire pressure. I might play around with it a little more now that i got my CST copperheads mounted today.
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    Quote Originally Posted by shiggy
    Some time you should actually put a clock (or GPS) on your runs and see how different pressures affect your speeds.

    I have done this with a Garmin Edge GPS when testing tires. The runs that felt the fastest were many times the slowest. They where exciting and it seemed I was going into the corners at a higher speed but in reality the tires where just bouncing and sliding more and harder to control. Slower into the turn and slower yet coming out of them. Heck, the higher pressure runs where even slower on the climbs.

    That is not to say the faster, low pressure runs were more fun. There was a lot less drama in covering the lap. Definitely not as thrilling a ride.
    in fact i do have timing device coming in the mail! yeah, it's hard to tell! that's why it's confusing to me. i'm always changing my presuures around to try and figure out what is best. i will try lower pressures, but i'm just not sure where to start. any ideas?

  17. #17
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    Over 190 with water and gear, 30 in the front and 32 in the rear with small 2.4's. These tires are definitively faster at 30-32 than they are at 40 or more whether I am on the road or the trail. I wouldn't have believed it if I had been told beforehand. I tried 28 in the front and 30 in the rear but felt the rim hit on both ends during that ride.

  18. #18
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    Quote Originally Posted by Spawne32
    22psi? isnt that kinda low? whats your tire look like while riding.
    It's fine. Remember, that pressure is in a wider 2.3-2.4 tire. Once you feel how your tires can conform to rocks and roots rather than bouncing off of them, you will appreciate lower pressures. To be honest, I've never had issues with pinch flatting. I think part of it is due to the the mainly rounded rocks we have around here (thanks glaciers), and part is due to the fact that I started mtn biking on rigid bikes and even though I run suspension now (front and full), I still unweight the bike as I go over and through stuff.

    I've played with all kinds of pressures over the years. In the early 90s I started running between 30 and 35 psi because I was new to MTB and the people that knew what they were talking about recommended lower pressures (that seemed low to me at the time). Later on I got sucked into the "higher pressure is faster" thinking and started running 40 - 45. I also remember that some tires during the mid 90s started coming with separate pressure recommendations if you were riding suspension versus rigid (min pressure on suspension was like 5 or 10 psi higher), so since I was running front suspension then (if you can call a 63mm Judy suspension), I went with the recommendations.

    Eventually (years later) I got sick of bouncing and glancing sideways off of every rock and root on the trail and started lowering my pressures again. Then in more recent years I discovered wider 2.3 - 2.4 XC tires (I had been running 1.95s to 2.1s up to that point) and even lower pressures, and a whole new world opened up to me. I was more than happy to trade some speed for better traction and control, but then I started reading in these forums that I probably wasn't sacrificing speed by running lower pressures anyway. So all is good . Now I just feel like an idiot for running 40-45psi for all those years.
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  19. #19
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    Quote Originally Posted by mr.niles
    in fact i do have timing device coming in the mail! yeah, it's hard to tell! that's why it's confusing to me. i'm always changing my presuures around to try and figure out what is best. i will try lower pressures, but i'm just not sure where to start. any ideas?
    The reason that most mtb tires are faster on dirt at lower pressures is really rather simple. A tire at lower pressure will flow or comform to bumps, smaller rocks, or square edged obsticals. A tire at higher psi doesn't do this, rather it has to make contact with the obstical and climb over it. This creates a bump that you can feel and in many cases the tire looses contact with the trail surface. It takes more time for the tire to bump over the obstical than it does to have it flow over it. The effects of higher pressure are, slower speed, less traction, less control. The lower pressure tire will have the opposite effect. But as the others have noted there is a limit to how low you can go. Rider weight, riding style, tire volume, tire construction, terrain, etc. all work to determine the "sweet spot" for a given tire. The sweet spot is that golden compormise pressure where the tire provides the best traction and performance without feeling squirmy or being so soft that you ding rims, etc. And I've never had two different tires that had the same sweet spot, and it takes a bit of work to find it. But if you go at it right it can be allot of fun.

    As for where to start, Surly29 had it right. Start with the lowest recommended pressure for the tire and ride it. If you don't get a pinch and the tire doesn't feel squirmy on the first run, drop pressure on the next run by 2 or 3 psi. If you do get a pinch or tire squirm up it by 2 or 3. So drag your pump and your bike to the trail and have fun. Oh and just as a side note, make sure you take a couple of spare tubes and have an inflation device along on the bike. Cause you will most likely pinch flat at least once.

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  20. #20
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    Spanw, believe Shiggy and all the others, they know what they're talking about with lower pressures. At your weight you should easily be able to ride anywhere from about 24PSI up to prob 35PSI for trails. It may not seem right, right now, but trust me When I first started I kept about 40 PSI in my tyres because it prevented pinch flats and helped them roll easier on the road. I've since come to realise that I needed the higher pressures with the tyre/rim combo I was using and my regular trail pressures now are between 24-30 PSI and I weigh 170lbs not geared up.

    Quote Originally Posted by Spawne32
    well im about 165 pounds and 40 psi in the rear is usually where i feel comfortable, adding a bit more flex to the front tire might make it a little easier on my arms but i dont know how much more difficult it would be to accel the bike forward with lower tire pressure. I might play around with it a little more now that i got my CST copperheads mounted today.
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  21. #21
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    Quote Originally Posted by trailville
    It's fine. Remember, that pressure is in a wider 2.3-2.4 tire. Once you feel how your tires can conform to rocks and roots rather than bouncing off of them, you will appreciate lower pressures. To be honest, I've never had issues with pinch flatting. I think part of it is due to the the mainly rounded rocks we have around here (thanks glaciers), and part is due to the fact that I started mtn biking on rigid bikes and even though I run suspension now (front and full), I still unweight the bike as I go over and through stuff.

    I've played with all kinds of pressures over the years. In the early 90s I started running between 30 and 35 psi because I was new to MTB and the people that knew what they were talking about recommended lower pressures (that seemed low to me at the time). Later on I got sucked into the "higher pressure is faster" thinking and started running 40 - 45. I also remember that some tires during the mid 90s started coming with separate pressure recommendations if you were riding suspension versus rigid (min pressure on suspension was like 5 or 10 psi higher), so since I was running front suspension then (if you can call a 63mm Judy suspension), I went with the recommendations.

    Eventually (years later) I got sick of bouncing and glancing sideways off of every rock and root on the trail and started lowering my pressures again. Then in more recent years I discovered wider 2.3 - 2.4 XC tires (I had been running 1.95s to 2.1s up to that point) and even lower pressures, and a whole new world opened up to me. I was more than happy to trade some speed for better traction and control, but then I started reading in these forums that I probably wasn't sacrificing speed by running lower pressures anyway. So all is good . Now I just feel like an idiot for running 40-45psi for all those years.
    Well said!
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  22. #22
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    Good job!

    Very well said trailville, Shiggy, Squash and others! How long will it take to beat it into people that lower PSI is better. I ride with guys that insist on running upwards of 45 PSI and if you are behind them you can see their tires bouncing all over the trail. When I mention lowering pressure mostly I get the response that they don't want to pinch flat and they brush me off . Oh well, their lose.

    BTW I'm 175 and on my Trek TF69er I run 22 PSI in the front Rampage 2.35 and 24 PSI in the rear Fat Albert 2.4, all tubeless with homebrew sealant (you should see my boogers!). And yes you can't just plow through rocks, roots and into logs. MTB riding should also incorporate at least a little finesse where you learn how to weight and un-weight the bike at the appropriate times.

  23. #23
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    Quote Originally Posted by Lugi
    I was curious to know what tire pressure is the best for all around xc use?
    I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
    I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
    Any suggestions would be great. Thanks
    This is like asking what shoe size to wear. It is greatly effected by tire size, the tire sidewall, your weight, and where you ride.

    I would start by lowering your pressure by a few pounds each ride until you either run into pinch flats or it just feels too soft.

    FWIW, I am ~185 with gear, and run ~23 psi front (2.4 Big Betty) ~30 rear (2.25 Ardent). East coast rocks and roots, but not much in the way of sharp edges.

  24. #24
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    i am curious about....

    what terrain and how you guys are riding it? shiggy, squash, trailville, lynx, kmacon, kapusta, le duke - how would you describe your riding style?

    i would have to say i ride like a gravity racer whenever the chance presents itself. when i brake, i cram the bike into the ground, when i corner i cram the tires onto their edge. i weight and unweight as quickly as i can, everywhere i can. i try to hit the best lines i can, but anytime the trail points downhill i am usually pinning it, so sometimes the best line is over the obstacles. of course this is not an absolute - there are pedestrians, horses, blind corners, etc that i always yeild to. but if i have a clear view, i push my limits.

    a little more remembering made me realized why i am running 36 psi in the rear tire: rim damage. long story shortened: several months ago i went out riding at one of my favorite places, riding it the way i like to ride it, and i had about 33-34 psi in my rear tire which seemed fine for the climbing and slower stuff. then i got to the fun part, and while bombing down the hill and really railing the corners something hit my rear tire so hard it bent the rim with a big "smack." i was very bummed because the rims are sun equalizer 29's and they weren't cheap. plus i had to do the whole junk task of changing a tube, not being able to pump it up enough etc, etc, not to mention losing out on finishing the bomb downhill because i had way too low pressure from not being able to pump it up enough. basically ruined the rest of my ride.

    on the other hand, 28 or even a little lower seems just fine in the front.

    another story: 2 weeks ago at northstar, i was having a great time riding all day with 36 psi in the rear tire (2 ply tire). then on my last run i decided to really pinnit down a somewhat rocky trail. i had a great run down, went to my car, loaded-up and went home. next morning had a flat on the rear - yep, big pinch slice. luckily i have big dh rims on that bike, so no rim dings.

    there have been other such incedences, but i will not include them here. overall, i have had the best "general" luck with 36 psi rear on a 2.1-2.35 tire with a single ply casing. maybe i am missing out on the benefits of lower pressure, but maybe i need the higher pressure to keep things together?

    so, does anyone think that i should still try lower pressures, or have i hit my "pinch limit" already? i will say that i HATE GETTING FLATS out on the trail, and i WILL NOT GO TUBELESS.

    i REALLY want to be able to go with lower pressures, because i DO know all about the tire conforming to the irregulaties using less energy to continue forward vs non-conforming, and i have ridden with lower pressures and experienced the way the tires "float" over the ground. but.....i have experienced problems going lower than 35 psi with the tires i like to use, so............

    ?????????????? what next????

  25. #25
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    Well Mr.Niles, first up I'll say this .......... Look into buying a GOOD frame [ump so if you get a flat you can inflate your tyre(s) back to whatever PSI you so desire Seriously if the POS you currently have can't even get you tyres back to 36 PSI, just toss it in the garbage, don't even think about it The pump I carry is a Topeak Mountain Morph and can inflate ROAD tyres back to 100 PSI when the need arises.

    Not sure how much skill I have or how hard I hit stuff, but so far I haven't managed to pinch flat a 29er My terrain down here in general is pretty slowish tech, with 1 or 2 DH's that have some rocks in them. I have one "nice" DH that I haven't ridden in over a year that's just a continous rock garden and last time I rode it was on my brand new Nano's, on my brand new RIP9, got way off line into the really rough stuff, faster than I normally ride the good line and didn't have a problem. However I will state that if I know I'm heading for that trail I prob run close to 30-32 PSI rear.
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