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  1. #201
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    I'm 150 pounds, and ride a hardtail. 35-40 psi is perfect, things roll faster, and pinch flats almost never happen. If your skills are up to the decrease in traction, than its wll worth the extra pressure for low rolling resistance, and running less risk of fixing a flat tire (nothing slows you down more) Even with a tubless set up, ride at least 30 or more to avoid the bead rolling and breaking the seal.
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  2. #202
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    For those running tubeless this is Stan's recommended starting point: divide your weight by 7, then subtract one for front pressure, add 2 for rear. For me at 200 lbs that works out to 28 front and 31 rear.

    Note that this the recommended starting point and not a firm rule. I am running 23 front and 26 rear on Maxxis Ikon 2.2.

  3. #203
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    I just checked my pressure. Did a ride today with the dogs so it was pretty slow paced. Pressures are read from Specialized floor pump with gauge.
    16psi front- felt a little low, bottomed the tire once but no flat.
    20 psi rear.
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  4. #204
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    Quote Originally Posted by mobius911 View Post
    For those running tubeless this is Stan's recommended starting point: divide your weight by 7, then subtract one for front pressure, add 2 for rear. For me at 200 lbs that works out to 28 front and 31 rear.

    Note that this the recommended starting point and not a firm rule. I am running 23 front and 26 rear on Maxxis Ikon 2.2.
    That formula does not take into account tire width, which is a big factor. When I run the formula for me, I get very close pressures to what I use on 26"/2.4" tires. But on my XC bike that uses 1.9 tires, I use 10-15 PSI more.

  5. #205
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    215 lbs male

    I run 35 in front with 2.3's and 40 in back with 2.1

  6. #206
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    I usually run 20-25 PSI in my rear 2.0 tire. Tubeless 29er. Yesterday I bent the hell out of my Stan's Crest wheel going through an armored creek crossing at average speed. I was pretty shocked. At a 140 lb body weight I rarely have issues with wheels. I guess I'm going to start running 30 psi.

  7. #207
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    190lbs with all my gear. 28 psi in the front, 32 psi in the rear on 2.24's

  8. #208
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    175lbs and I run (pending trail and conditions) anywhere between 38 to 42. For the most part on faster trails the higher pressure and slower trail the lesser pressure.

    Mud I let a little out, sticky trails higher and dry usually I use the feel factor (if the tire is not sticking I let a touch out till it feels good)

    Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/

  9. #209
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    Quote Originally Posted by spartacus View Post
    175lbs and I run (pending trail and conditions) anywhere between 38 to 42. For the most part on faster trails the higher pressure and slower trail the lesser pressure.

    Mud I let a little out, sticky trails higher and dry usually I use the feel factor (if the tire is not sticking I let a touch out till it feels good)

    Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/
    Basically, on a rough surface higher pressures bounce more. the tire/wheel moves up more than forward.

    Lower pressure lets the tire conform to the terrain and maintain forward momentum.

    Same reason suspension is faster than rigid on rough terrain.
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  10. #210
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    Thank You. This makes sense
    I keep hearing this from some of the people out by me and it perplexed me because there was no explanation. I think they Just conveyed info they herd with out understanding why.

  11. #211
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    Quote Originally Posted by shiggy View Post
    Basically, on a rough surface higher pressures bounce more. the tire/wheel moves up more than forward.

    Lower pressure lets the tire conform to the terrain and maintain forward momentum.

    Same reason suspension is faster than rigid on rough terrain.
    No, that is not the theory. The theory is that a wider tyre is faster than a narrower tyre for MTB use because the longer, thinner contact patch requires the tyre to "lift" more than a fat narrow one. Schwalbe did a study looking at this and concluded as above. Some of the benefit is small (around 10watts IIRC) but some was surprisingly large. Depending upon the type of terrain. Note that on hard surfaces, (i.e. road bike) the opposite is true.

    WRT tyre pressure - as the decrease in pressure allows the above effect to occur, it will be faster, but at some point the extra drag of the bigger contact patch will have the opposite effect.

    Remember that simple physics means that the actual size of the tyre has no effect on the contact patch size - it is only the air pressure in the tyre. In other words a 26x1 tyre running 30psi will have the same contact patch size as a 29x2.3 tyre @30psi. The shape will change (long and thin vs short and fat), but the size won't. Generally speaking the long thin contact patch (narrower tyre) will have advantages in traction and braking, whilst the short and fat contact patch (wider tyre) will have advantages in cornering.

    This is why decreasing tyre pressure increases contact patch size which will improve traction due to the greater tyre surface area interaction with the terrain.

  12. #212
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    I am Mr 30 psi on both my Tubeless Ready Tire sets on both UST rimsets. Accidentally rode 25 psi tonight! I am now Mr 25 psi

  13. #213
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    I would add that pressures required depend on terrain. I did a 11 mile climb the other day on my steel rigid 8 speed, was great uphill with 40 rear 35 front. But then the washboard on the way down was crazy! I prob let out almost 20lbs on both wheels. Only way I could maintain control at speeds of 25-30mph. Had I had suspension with tubeless, I would have maintained the same pressures.

  14. #214
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    Quote Originally Posted by spartacus View Post
    Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/

    Studies show you're faster when you can stay connected to the trail. Larger contact patch=more traction=faster
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  15. #215
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    Quote Originally Posted by ZXFT View Post
    Studies show you're faster when you can stay connected to the trail. Larger contact patch=more traction=faster
    Also I would imagine some tire deflection over smaller bumps uses less energy than a harder tire transmitting that energy through the frame, suspension and even rider...
    just my two cents.....

    Plus more traction as stated above...

    My two cents .....

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  16. #216
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    Quote Originally Posted by Rum Runner View Post
    Also I would imagine some tire deflection over smaller bumps uses less energy than a harder tire transmitting that energy through the frame, suspension and even rider...
    just my two cents.....

    Plus more traction as stated above...

    My two cents .....

    Cheers,
    Paul
    Makes sense. When suspension moves most of the energy is lost in damping.

  17. #217
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    Its kinda like the 29er argument: If it rolls smoother, it will be faster.
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  18. #218
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    36 psi.. sounds pretty reasonable to me...

  19. #219
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    Quote Originally Posted by snowgage View Post
    36 psi.. sounds pretty reasonable to me...
    Reasonable to who? Riding what?
    It depends on tire width, terrain, rider weight, rim width, tube/tubeless among other things. Just for myself I run 22-40 PSI in different bikes (used on the same trails).

  20. #220
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    I weigh about 83kg and have been running 25 front/ 28 rear, Racing Ralph 2.25 tyres on loose/ rocky conditions. Managed to put a dent in my carbon Roval front rim on the weekend from hitting a rock so i'll be adding a few psi of pressure from now on. Bit less grip but better than destroying carbon rims.

  21. #221
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    Great post with lots of input. I read all the posts and did as some suggested and took my bike and floor pump with gauge down to my little single track loop with one steep and rocky descent with a narrow bridge at the end. I started with pressure in the upper 30psi range in both tires and played around. I ended up with 25 for the front and 28 for the back and the increased handling was great and very noticeable in overall control and less "bouncing" when compared to the higher tire pressures.

  22. #222
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    Prefer 25 psi on the front, 30 psi on the back.

  23. #223
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    im 170 lbs

    On a previous bike with 2.4 Maxxis advantages, I preferred 28 psi front, 30 rear

    I recently bought a Cannondale RZ 120 and went with 2.1 Kenda Nevegals. I prefer to be at 35 psi otherwise it feels way too squirmy in the corners. Although I find starting at 40 psi its noticeable too hard over roots.

    all tubed tires

  24. #224
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    3,5bar in Specialized Storm Control 26x2.0

  25. #225
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    3 bar in racing ralph 26x2,25

    But i might be way off.

  26. #226
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    Quote Originally Posted by Bech View Post
    3 bar in racing ralph 26x2,25

    But i might be way off.
    Does 1 bar = 15psi?

  27. #227
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    Quote Originally Posted by fsrxc View Post
    Does 1 bar = 15psi?
    1 bar = 14.5037738 pounds per square inch (no, i didnt know that off the top of my head. I used google)

  28. #228
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    14.5psi equals 1 bar

  29. #229
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    Some high pressures being run. I usually shoot for 28psi but I'll run 25psi if that's what it's leaked down too.

  30. #230
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    It really depends on the tires, trail conditions, and riding style, I can run from 18 to 30 front and 20 to 40 rear

  31. #231
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    run 50 psi

  32. #232
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    I'm 59 yrs old, 165 lbs, medium fast on the descents in Park City Utah. Primarily interested in climbing speed. I had been running 28 PSI in front (on a Yeti 575 with a 150 mm front fork) on a WeirWolf LT 2.55 and 30 PSI on a 2.30 Tioga Psycho Genius on the back (on Stan's Crest rims, tubeless). More than a 2 PSI decrease causes the tires to begin to fold under while cornering. I have now placed Conti X-King, 2.4 RS front and back, tubeless, and find I still need to run 30 rear and 28 front to get the same resistance to the fold under while cornering. I'd run lower pressure were it not for the cornering issue because it makes climbing a dream.

  33. #233
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    Cool-blue Rhythm

    155lbs - I am running ADventage tubeless and I ran 40psi back and front this week.
    I encountered some front wheel control issues on soft over hard, OK my lack of skills is probably the number one factor but my tire pressure may have been too high. I never had the same feelings when running 20-30 psi.

  34. #234
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    I'm not racing (yet), but been riding since the 90's. I started out running tubes and 50 psi back then and now I run tubeless and in the range of 23-26. I'm 160 pounds and have ridden Continentals pretty much all of the time with my preference now with Trail Kings with a 2.2 in the back and a 2.4 in the front. I've been experimenting with the tubeless version vs. the non-tubeless version and it seems even in the rocky and rooty areas that I ride that the lighter, non tubeless versions holds up just fine.

    After running tubes and high pressures and then no tubes and low pressure, I confidently feel there is no comparison between the two in terms of speed and confidence. I've also discovered that I can convert just about any rim to run tubeless with just stan's tape and a valve. One rim I had was stubborn and I had to add a layer of gorilla tape over the rim tape to get it to seal, but I think just about any crappy rim can be converted with the help of an air compressor.

  35. #235
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    Quote Originally Posted by vttix View Post
    155lbs - I am running ADventage tubeless and I ran 40psi back and front this week.
    I encountered some front wheel control issues on soft over hard, OK my lack of skills is probably the number one factor but my tire pressure may have been too high. I never had the same feelings when running 20-30 psi.
    Yes, 40psi in the front tire could be reducing traction and control.

  36. #236
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    25ish. I weigh 140.

  37. #237
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    Around 35 with 190 pounds on the bike. Much less and the tires squirm and squeal over obstacles.

  38. #238
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    I'm running 20psi front and 24psi rear with Specialized LK Control 2bliss tires in 2.0 width with Stans rim strips and a home brew sealant. I'm 160 pounds with an average riding style, no huge jumps or anything like that. I mainly ride on loose gravel/decomposed granite over concrete like hardpack.

  39. #239
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    Apparently, it also depends greatly on your pressure gauge. I finally got a good quality gauge. It's about 5 PSI lower than my floor pump and 4 PSI...in the other direction...from another tire gauge I have.

  40. #240
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    why are you guys running such high pressures? What kind of terrain are you running?

    I run 20ish up front and 25ish in the back. I ride sandy hard pack with roots and lots of pine straw and leaves. If I raise the pressure to 25 in the front it slides all over the place, the front washes out like crazy. If I leave it at 18 to 20 it rides great. I hit roots and large curb sized roots with no problem at all. I could not imagine running 30 or 40.

    I have a 2.2 ikon exo up front (or 2.4 ardent) depending on the weather and a crossmark 2.1 out back.
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  41. #241
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    The tires that are "high pressure" tires, such as the Maxxis Ikon, what are you guys running in them. I'm about 230# and riding in hardpack/rocky/loose over hp, with 29 x 2.2 Ikons. Should I just run them at the normal (for me) 35ish psi? Or should they be run with higher pressure. What is the advantage of having a high pressure tire?

  42. #242
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    Quote Originally Posted by smokehouse4444 View Post
    The tires that are "high pressure" tires, such as the Maxxis Ikon, what are you guys running in them. I'm about 230# and riding in hardpack/rocky/loose over hp, with 29 x 2.2 Ikons. Should I just run them at the normal (for me) 35ish psi? Or should they be run with higher pressure. What is the advantage of having a high pressure tire?
    I would definitly do some testing, start at 35psi and work your way down to where you'll get the most amount of grip without dinging the rims and or rolling the tires under, during hard cornering. I own Ikons also and weigh 150lbs with a 25lbs bike full riding gear is 175lbs total, I run 25-28 psi in mine front, and alittle more in the rear like 30-35 to help decrease rolling resistance , ran tubeless. On the road rides on my mountain bike I jack em up to 40psi

  43. #243
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    I'm 185lbs, running 35psi F 38psi R on Maxxis crossmark 2.0 with Dt Swiss X1600 rims for a few weeks since converting to tubeless, so far so good......climb better and no more flats........will try to lower a couple psi this weekend....see how it handles.....

  44. #244
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    We the people ...

    Are you all racing or something. I use too race and neve:crazy paid that close attention to PSI ever. All I have ever done was put in about 40 in remembering how hard or easy it was to sqeeze and go ride. Not that you can't notice a difference in a 3-4 psi change, but you would have to be tuned into your bike pretty well to notice it. Besides that if I were to run anything less than 30 psi I would get snakebit every time out.

  45. #245
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    Quote Originally Posted by redd4573 View Post
    Not that you can't notice a difference in a 3-4 psi change, but you would have to be tuned into your bike pretty well to notice it.
    IMO +/- 3-4 psi is a huge difference that doesnt require a 6th sense to detect.

    Quote Originally Posted by redd4573 View Post
    Besides that if I were to run anything less than 30 psi I would get snakebit every time out.
    Tubeless man... Its the way of the future.
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  46. #246
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    Recommendations on pressure. Just got a '12 Dawes Haymaker 1200 17" with this setup

    Rims WTB Speed Disc Double Wall Aluminum
    Tires WTB Velociraptor Blackwall 26 x 2.10

    Sidewall says 40-60 so I put them at 50. I am 135# and a total noob. I ride mostly well packed gravel trail with a few pretty clear dirt trails with minimal roots and rocks. 50 felt good, but my hands were numb after a 15 minute ride on these dirt trails. I know there could a lot of other factors to that but hoping for a bit more cush if I lower the tire pressure.

  47. #247
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    At 135lbs I'd say you should be in the mid 20's psi wise. 50 is just crazy

  48. #248
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    180lbs... run 24psi front & 27psi rear in just about all my tubeless set ups no matter the tire (mostly schwalbe's)

  49. #249
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    Tubeless. 33 psi rear and only 16 psi front in a 2.25" tire - I have a rigid fork so it's my only suspension. Never burped... yet

  50. #250
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    Great at this rate we will be talking nito and beadlocks soon Now lets use our heads a little better than we have been . Tire makers have invested alot of $$$ in R&D, I personally run Panaracer Dart and Smoke Tube combo .I find they work for me. I run roughly 35-40 psi, I say roughly because I really only get as close as I need to be because most tire guages are very inaccurate anyways get any three different ones and try it. That being said the side walls on my tires read recomended psi between 30-50 psi. Now I'm not cracking on anyone's veiw on this topic but I believe the tire makers are spot on. I have had little issues with traction outside of poor judgement in placement of said tires. If you look at a correctly inflated tire from the approching angle it revels a crown, if one were to lay the wheel and tire at say 15 - 20 degrees to the left or right the contact area remains the same. And with weight on the bike say all of my 200lbs I could find the tires rolling a bit and increasing this area.Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison but it's not to far off point. But the most important thing is we all have fun riding even if it seems goofy how others do things

  51. #251
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    ah yes but if you were running tubeless with UST tires the bead sits tighter, then throw in no suspension and a nice fat tire and all you need is low pressure for less stress on the wrists.
    OK so I wouldnt do it in my car but then I dont go 100 mph on my bike...

  52. #252
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    Quote Originally Posted by redd4573 View Post
    Great at this rate we will be talking nito and beadlocks soon Now lets use our heads a little better than we have been . Tire makers have invested alot of $$$ in R&D, I personally run Panaracer Dart and Smoke Tube combo .I find they work for me. I run roughly 35-40 psi, I say roughly because I really only get as close as I need to be because most tire guages are very inaccurate anyways get any three different ones and try it. That being said the side walls on my tires read recomended psi between 30-50 psi. Now I'm not cracking on anyone's veiw on this topic but I believe the tire makers are spot on. I have had little issues with traction outside of poor judgement in placement of said tires. If you look at a correctly inflated tire from the approching angle it revels a crown, if one were to lay the wheel and tire at say 15 - 20 degrees to the left or right the contact area remains the same. And with weight on the bike say all of my 200lbs I could find the tires rolling a bit and increasing this area.Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison but it's not to far off point. But the most important thing is we all have fun riding even if it seems goofy how others do things
    You're also running tires developed like 20+ years ago and they're standard clinchers. Try running tubeless and you'll change your views. PS my tires have a MAX of 40 psi

  53. #253
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    My front tire is around 2,2bar, rear is 2,5bar. Good traction, I don't like high pressures at all.
    Ride to live, live to ride!!!

  54. #254
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    I have no need to ride tubless . Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up

  55. #255
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    No mounting issues, don't carry a spare, low tire pressure, takes 10 min to mount tubeless, no flats in over 2 years since going tubeless, and forgot what a tube even looks like. Loving the tubeless kool-aid.

  56. #256
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    No good

    Quote Originally Posted by redd4573 View Post
    I have no need to ride tubless . Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up
    While I dont ride tubeless, im educated enough on the subject to realize youre completely out of touch with reality. Engaging in attempts to correct you, as another has already realized, is fruitless.

    With a recent registration date and 13 posts, id suggest lurking and reading more and posting a tad less.

  57. #257
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    Gonna go lurk and read how to install tubes and up my tire pressure in order to make my riding more enjoyable, thanks for the recommendation!

    #FeelingsHurt

  58. #258
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    Quote Originally Posted by jacksonj51 View Post
    No mounting issues, don't carry a spare, low tire pressure, takes 10 min to mount tubeless, no flats in over 2 years since going tubeless, and forgot what a tube even looks like. Loving the tubeless kool-aid.
    LOL this exactly. I run tubeless compatible rims and tires and it's super easy to use and has been dead nuts reliable.

  59. #259
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    redd,
    I fully understand not wanting to get caught up on all the equipment hype, but as someone that spent many years exclusively with the Dart/Smoke combo (I ran them for over a decade) I strongly encourage you to try some new tires. There are much better tires available today.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  60. #260
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    Wow you guys are easy. I've been riding for close to 20 yrs I have seen things come and go some great some not so much. I have tried many diferent types of tires and I do run a couple semi slicks later in the summer if trails stay dry more and soft spots firm up. Like I have stated before this is just my opion I supose we are all allowed to have one. For me mtbing is a way to relax and injoy life. See inside these last 20 yrs I've raced and trained my way into as I called it cycling slavery. Not to say that all that doesn't or can't make others happy but it's not for me and after slowing down I saw this sport as I did when I first started riding, SIMPLE. Just passing some zen like info on to others open to those who like a sound debate. If I upset anyone..... well sorry I was to busy riding and not lurking on a forum learning proper etiquette Hope to meet you all on the trail someday. Oh and I will not be hard to find I will be the slow guy you are passing with the retro tires on a hardtail with a smile on his face.

  61. #261
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    Smile

    Quote Originally Posted by redd4573 View Post
    I have no need to ride tubless . Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up
    Tubeless is about physics. You run lower pressures. Benefits in traction and braking (=speed). And way less flats. I have had 1 flat in the last 4 years of running tubeless.

    And I checked, the earth is not flat.

  62. #262
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    Quote Originally Posted by redd4573 View Post
    Wow you guys are easy. I've been riding for close to 20 yrs I have seen things come and go some great some not so much.
    I know, tubeless is a fad, just like disc brakes and suspension forks.
    Something wrong with your bike? Blame it on super human strength and sleep well at night knowing you are more than a man.

  63. #263
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    Quote Originally Posted by redd4573 View Post
    I have no need to ride tubless . Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up
    If you live where we do you need to run tubeless otherwise you'd go crazy - at least one puncture every ride. It's the hoarthorn and blackthorn and bloody whoknowswhatthorn but they get in your tubes mate...

    And in any case ghetto tubeless doesn't generate much profit for anyone, and loses the tube makers some.

  64. #264
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    I donít have a gauge, so I donít really know what I run my tires at (and gauges are notoriously inconsistent anyway Ė well, consistent with themselves but not from one gauge to another). I just do it by feel. Generally I use the squirrely cornering rule. If I am feeling that, I inflate what I guess is probably 2-3 psi and see how it feels. Iím running new tires now (2.4 in front and 2.35 in back, up from 2.1s) so Iím still playing with getting the right feel. But generally, I like it as low as it can go before I start to feel that cornering squiggle. Iím riding all rigid (and loving it!) so I value the extra give. Itís a better feeling, too, to be running lower. Like I am more inside the terrain than just on top.

  65. #265
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    Quote Originally Posted by wahday View Post
    I donít have a gauge, so I donít really know what I run my tires at (and gauges are notoriously inconsistent anyway Ė well, consistent with themselves but not from one gauge to another). I just do it by feel. Generally I use the squirrely cornering rule. If I am feeling that, I inflate what I guess is probably 2-3 psi and see how it feels. Iím running new tires now (2.4 in front and 2.35 in back, up from 2.1s) so Iím still playing with getting the right feel. But generally, I like it as low as it can go before I start to feel that cornering squiggle. Iím riding all rigid (and loving it!) so I value the extra give. Itís a better feeling, too, to be running lower. Like I am more inside the terrain than just on top.
    Because if there's anything more accurate than a numerical gauge it's the human touch.......

  66. #266
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    I run my Nobby Nic's 2.1 on 2.3bar with latex tubes. They are very soft compared to Smart Sam and Albert.

  67. #267
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    Quote Originally Posted by Ilikebmx999 View Post
    Because if there's anything more accurate than a numerical gauge it's the human touch.......
    Touche!

    My point was simply that just because Jimmy's gauge reads 25psi, it won't necessarily be the same as 25psi on your gauge. So don't take other peoples' numbers too seriously - make your own adjustments for what feels best. Use your own gauge if you want (and always use the same one), but as far as seeking a "standard" pressure, that's going to be hard to nail down with so much variability (in gauges, tires, riders, etc.)

    The truth is I'm too lazy and cheap to go get a gauge, so I ride and make adjustments for what feels best. And while the ladies say I have a magical touch, you're right, I'm not a human pressure gauge...

  68. #268
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    Got wrapped up in all the hype and bought a decent (expensive) digital pressure guage. Can't believe what I'm reading on it (and riding on)!

    Also riding rigid, so I value a soft fat tire up front, but I measured the pressure last night (after reading these posts) and it was 13 psi

    Can that be right? It feels soft, but I don't get the squiggly corners yet. It feels just right - a bit of suspension and really good grip. It is a Nobby Nic 2.25" snakeskin running tubeless...

    (Rear is different - that's at 33 psi which feels like it's right)

  69. #269
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    I got a new tubeless wheel set in the fall and have now had some rides and a race on them and I can say I am definitely having a positive experience running UST tubeless rims and tires.
    Running Mountain King 2.2's and really liking them.
    I had to add just the smallest amount of Stans to seal around the valve stem and totally seal off the bead. Probably 1/2 oz in each tire. They held air all winter hanging in the garage and so far seem to be holding air well.
    I started out around 25 psi and each ride dropped a little and this past weekend and the first race 2 days ago I ran approx 18-19 psi F/R (GT i-drive FS, 145lbs rider)
    I have been able to clear tough sections better than most so this means I have pretty good traction due to the variety of tires the other guys are riding on. I won't go lower than this and maybe up a pound or 2 for race days as our course is rough rocky and rooty.
    At the local races last year I only finished 3-7 races due to multiple flats. This first race I didn't hold back, other than building up some confidence, over the 3 laps and no flats ! I did look down a few times though.

    Cheers,
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  70. #270
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    Quote Originally Posted by redd4573 View Post
    Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison
    Actually you are not far off, and YES, I WILL GO AND DEFLATE MY VEHICLE TIRES TO GAIN TRACTION!!! Every time I take my Jeep off road or when I need the extra traction here in the great NorthEast in the snowy season, I will deflate my tires just to gain that extra traction.

    That said, I fully understand the low psi and the benifits of it. I myself do not run lower psi on my MTB because I have not had the need to YET. When I find myself riding trails more regularly that require me to do so, I will.

    As far as to say whats better, tubes or tubeless, it depends on what you need for where you ride.

    So how low is too low? Well thats up to you to decide for yourself. I could ask a few questions on the subject, but seeing as this whole thing is a hotly debated subject to begin with, I will leave my questions out for now. A lot of what I wanted to ask about has already be said, so I will leave it at that.

    As to the arguement about "riding for 20 years," does not make you an expert. I have been riding since I was 5yrs old, that means I have been riding for the last 28 years, am I am expert, absolutly not. Will I pretend to be something I am not, heck no. Anyone who has lived and paid the slightest bit of attention has seen fads come and go.

    That all said, did I say you lied, NO, did I hurt someones feelings by what I said, ehh maybe, it happens, its life.

    Bottom line: It doesnt really matter unless you are happy and enjoying your setup on your bike. There are a ton of variables that go into YOUR setup of YOUR bike. Yes it is good to seek opinion in order to educate ones self, but it is bad when you belittle the opinion becasue it is not like your own.

  71. #271
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    Did the voices come back I never claimed to be a expert. Just trying to have a good discusion and a gain and understand of others opinons. How does stating MY opinon belittle others? But then agin I'm not an expert on THOSE sort of things

  72. #272
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    I rode at the weekend with 40 psi in my Continental Rubber Queens (2.2). The downhill was terrible, I'll be looking to come down to around 30 psi.

  73. #273
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    Quote Originally Posted by redd4573 View Post
    Did the voices come back I never claimed to be a expert. Just trying to have a good discusion and a gain and understand of others opinons. How does stating MY opinon belittle others? But then agin I'm not an expert on THOSE sort of things
    I say it like I see it, I did not say that YOUR particular post/opinion quoted was in question, but after reading a few pages of replies and seeing posts that were negative in nature because one persons opinion differed from theirs, I felt the need to say it.

    I have seen it before where people think that because they have been doing something for XX years that they are gods gift to (fill in the blank). It is typically these people that are almost always wrong and give bad advice. Your post was the last one read by myself, so it was the one used as an example. If I was calling you out directly, I would have typed your screen name in directly. The only thing I said that was in your direction redd4573 was the very first paragraph about airing down just to gain traction.

    Everything else I had to say was a general statement put out there and not directed towards anyone in particular. nothing more, nothing less.

  74. #274
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    I don't think anyone can seriously debate the benefits on traction of deflating a tyre. After all the size of the tyre (width, height, diameter) is irrelevant in determining the size of the contact patch - the only relevant factors are the total weight and the PSI in the tyres. Simple physics. Put another way, a 26er running a 1" wide tyre will have the same contact patch size as a equivalent weight 29er running a 3" wide tyre, provided that they are running the same PSI. Different shape, but same total size.

    SO I can double my contact patch size by running 20psi when I used to run 40psi. Benefits are in better traction, braking and cornering. That is until the negative effects of tyre movement rob the bike of the control necessary to handle comfortably. Or I puncture too often. Or both.

    So, it is better to adopt the approach of achieving the minimum pressure to produce the results you are looking for, than the other way around.

  75. #275
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    Quote Originally Posted by skiwi View Post
    I don't think anyone can seriously debate the benefits on traction of deflating a tyre. After all the size of the tyre (width, height, diameter) is irrelevant in determining the size of the contact patch - the only relevant factors are the total weight and the PSI in the tyres. Simple physics. Put another way, a 26er running a 1" wide tyre will have the same contact patch size as a equivalent weight 29er running a 3" wide tyre, provided that they are running the same PSI. Different shape, but same total size.

    SO I can double my contact patch size by running 20psi when I used to run 40psi. Benefits are in better traction, braking and cornering. That is until the negative effects of tyre movement rob the bike of the control necessary to handle comfortably. Or I puncture too often. Or both.

    So, it is better to adopt the approach of achieving the minimum pressure to produce the results you are looking for, than the other way around.
    ..........uhhhh

  76. #276
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    I use TLAR* ie my thumb.


    *that looks about right.


    I usually adjust the tire pressure to the conditions of the trail.

  77. #277
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    Quote Originally Posted by Ilikebmx999 View Post
    ..........uhhhh
    Like I said - simple physics. And most people into cars & bikes don't get it. Like you I take it....

  78. #278
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    Quote Originally Posted by skiwi View Post
    Like I said - simple physics. And most people into cars & bikes don't get it. Like you I take it....
    So let's say a 200 lb rider sitting on a bike with a 1" wide tire at 20psi and a 200 lb rider sitting on a bike with a 3" wide tire at 20 psi will have the exact same contact patch?

  79. #279
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    Quote Originally Posted by Ilikebmx999 View Post
    So let's say a 200 lb rider sitting on a bike with a 1" wide tire at 20psi and a 200 lb rider sitting on a bike with a 3" wide tire at 20 psi will have the exact same contact patch?
    No, they will have the exact same size contact patch. The shape will be different.

  80. #280
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    Quote Originally Posted by skiwi View Post
    No, they will have the exact same size contact patch. The shape will be different.
    How is contact patch and size of contact patch not the same thing?

    The amount of tire touching the ground will be exactly the same is what you're saying then?

  81. #281
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    Quote Originally Posted by Ilikebmx999 View Post
    How is contact patch and size of contact patch not the same thing?

    The amount of tire touching the ground will be exactly the same is what you're saying then?
    Contact patch size and shape are different things.

    PSI is pounds per sq inch.That is the only thing holding up the weight of the bike/rider (less some sidewall stiffness).

    So, in your example, 200lbs/20psi = 10sq inches. That is your total contact patch size (5 sq inches per tyre). For both the 3" wide tyre and the 1" wide tyre.

    Contact patch size stays the same, but shape doesn't. As your tyre goes wider (at the same pressure), the contact patch shortens and widens. Hence you are trading off traction & braking for cornering.

  82. #282
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    You brought up shape not me. I'm specifically talking about the amount of tire touching the ground.

  83. #283
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    It will be the same. Same total area. Different shape.

  84. #284
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    I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.

  85. #285
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    Quote Originally Posted by Ilikebmx999 View Post
    I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.
    BTW, this is no "theory". It is simple fact. It applies to Tarmac and Dirt equally (albeit with different trade offs). If you don't believe it works this way, wander down to your local 4wd club and try and convince them about your understanding of the physics ;-)

    Good luck with that.

  86. #286
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    Quote Originally Posted by Ilikebmx999 View Post
    I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.
    Its not "his theory", its basic physics. The contact area will be more or less the same, maybe the wider tire will have a few more knobs on the side touching the ground at lower pressure, making the patch a tad larger, but not significantly larger.
    If we take a completely smooth tire with a thin carcass (like a road bike) then the area will be almost identical for the same pressure.

  87. #287
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    so what your are telling me is that my contact patch will be the same as everyone elses at 20 psi even though I am 300lbs and someone else is 150lbs? I understand that it might not be a significant change in the size or shape of the patch, but I would have to disagree that the contact patch will be exactly the same regardless of bike and rider weight with different size/width tires.

    If you have a 1 inch wide tire and a 3 inch wide tire both at 20 psi, the 3 inch wide tire is gonna have a larger contact patch on the same bike with the same rider.

    I know it is considered apples and oranges here, but I have to make the comparison. This would be like you saying that the contact patch of a vehicle tire but on the same truck is exactly the same regardless of its width. A 12.5 inch wide vehicle tire has a larger patch over the same tire in a skinnier width.

  88. #288
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    At the risk of being flamed, i didn't read the whole thread... no that's not what he is saying. For a 300lb load at the same psi your total contact patch area is the same whether it is a 1" or 3" wide tire.

    300lb/20 psi = 15 Sq. In

    Now, if you only have a 150lb rider at the same pressure, your contact area is reduced...
    150lb/20psi = 7.5 sq. in.

    Having said that, in all honesty, you may not be running the same pressure to generate the same 'feeling' for the rider (after all tire 'squish does act as the 1st bit of suspension)... but that's what they were trying to state.
    Last edited by joqpub4; 06-01-2012 at 12:29 PM.
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    Why am I on the computer and not riding???

  89. #289
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    Quote Originally Posted by bandit1 View Post
    so what your are telling me is that my contact patch will be the same as everyone elses at 20 psi even though I am 300lbs and someone else is 150lbs? I understand that it might not be a significant change in the size or shape of the patch, but I would have to disagree that the contact patch will be exactly the same regardless of bike and rider weight with different size/width tires.

    If you have a 1 inch wide tire and a 3 inch wide tire both at 20 psi, the 3 inch wide tire is gonna have a larger contact patch on the same bike with the same rider.

    I know it is considered apples and oranges here, but I have to make the comparison. This would be like you saying that the contact patch of a vehicle tire but on the same truck is exactly the same regardless of its width. A 12.5 inch wide vehicle tire has a larger patch over the same tire in a skinnier width.
    No, If you are 300ilbs and another person is 150lbs then the different weights would mean different contact patch sizes, if you are running the same PSI. If you have 2 people the same weight, and running the same PSI, then the contact patch size wold be the same - regardless of the size of the tyre.

  90. #290
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    Quote Originally Posted by joqpub4 View Post
    At the risk of being flamed, i didn't read the whole thread... no that's not what he is saying. For a 300lb load at the same psi your total contact patch area is the same whether it is a 1" or 3" wide tire.

    300lb/20 psi = 15 Sq. In

    Now, if you only have a 150lb rider at the same pressure, your contact area is reduced...
    150lb/20psi = 7.5 sq. in.

    Having said that, in all honesty, you may not be running the same pressure to generate the same 'feeling' for the rider (after all tire 'squish does act as the 1st bit of suspension)... but that's what they were trying to state.
    Exactly. It's an important concept to get across in the debate about how to get the best performance out of your bike.

  91. #291
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    After reading an article on the subject, I think I understand the whole concept better... I will share an excert of the article I just read about this subject.

    Tire Width. There is a view that a 20 mm width tire is faster than a 23 by virtue of its smaller cross section and lighter weight. Interestingly enough, this is not true. The people making the Torelli tires had noticed that the pro teams that they sponsored asked for 23s because they felt they were faster. When they investigated and did the testing, they found that the riders were correct. Let me explain.

    Let's assume a 200 pound rider and bike unit. Let's also assume that the weight is distributed half over each wheel. That means that each wheel is supporting 100 pounds. Now, with a pressure of 100 pounds per square inch, the contact patch is one square inch. This is true no matter how fat the tire.

    What changes when the tire gets fatter is the shape of the contact patch. With a 20, the contact patch is a long oval. With the fatter tire, the contact patch gets shorter and wider.

    When a rider is using a skinnier tire, the long contact patch means he is flexing a wider arc of the tire casing, flexing more of the tire, causing more wasted energy from the internal friction of the tire and tube. The rider with the fatter tire is flexing fewer cords at a time.

    There is clearly an optimum size, and the fact that racing tubulars are around 22 should keep us from getting super wide tires looking for yet more speed. Other losses probably kick in as the tire gets still fatter. For me, the bike feels like it doesn't have any snap or jump when we stray from the optimum which I believe to be in that 22-23 mm range.

    Some have suggested that the skinnier tires make up for their losses because of their lower aerodynamic drag. This could be true for the solo time-trialist, I'm not sure. For the pack rider, it clearly is not an important consideration.
    Here for the full article

    There is also this one but it refers to motor vehicle tires.

  92. #292
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    Quote Originally Posted by bandit1 View Post
    After reading an article on the subject, I think I understand the whole concept better... I will share an excert of the article I just read about this subject.
    Good summary and entirely correct. Interestingly, there is similar evidence (albeit from Schwalbe) of the same effect in MTB i.e. wider is faster.

  93. #293
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    yea there are some articles that get into it deep talking about what happens at the leading edge of the contact patch with rolling resistance and the rubber fibers bending and what not. Made my head hurt reading it.

  94. #294
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    Quote Originally Posted by bandit1 View Post
    yea there are some articles that get into it deep talking about what happens at the leading edge of the contact patch with rolling resistance and the rubber fibers bending and what not. Made my head hurt reading it.
    I used to care about it as I tried to get my 26er race bike faster. Definitely proved it to my own satisfaction. However since migrating to a 29er, the dynamics are entirely different, and I've forgotten all about it. The 29er is plenty fast without obsessing about contact patch shapes...

  95. #295
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    Tire pressure varies for each tire. Tubed or tubeless? Front or back? You can go lower w/out tubes, and see improved performance. Experiment. I like 2-3 lbs. less up front than in rear. I also like a completely different tire for each (front and rear), since I believe they are responsible for two totally different things. Weight also impacts tire pressure, as does conditions and what you expect from your tires.

    I like tubeless, and I find my sweet spot on my tires tends to be in the mid 20's. Your tires may be entirely different.

  96. #296
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    140lb rider, 23lb FS bike, Norcal XC riding including some technical...

    Front: 20 psi, Nobby Nic 26x2.25 EVO Snakeskin
    Rear: 23 psi, Racing Ralph 26x2.25 EVO Snakeskin

    I run both tires tubed and have not come close to pinching. I can get away with really low psi as I am light and these tires can be run at ridiculously low pressures. Fantastic grip for dry summer conditions and the extra volume provides some nice cush. Front tire just rails and the rear tire tracks nicely, but still kicks out when needed.
    Last edited by Fiendbear; 07-10-2012 at 04:36 PM.

  97. #297
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    255lbs on 2.1s running 30/30. I've run as low as 24/24 after forgetting to check pressure before a ride and felt the rim on a rock or two but no flats.

  98. #298
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    I used to be a 200 lbs XC rider on a hardtail and my pressure was 42 front/45 rear PSI. Now I weigh 170 lbs and I also changed my wheels to XT M785 (UST rim). I run tubeless front (RocketRon 2.25 Evo TLR) and tube-type rear (RocketRon 2.25 Evo TLR). The rear was also mounted tubeless but I cut it ,so I had to use a tube.Since my new wheelset and weight loss I droped the pressure to about 33f/35r. I would like to try really low pressures to see how it feels,but the instructions on the Shimano site says the pressure should be between 29 and 58 PSI.
    I read here about pressures as low as 18 PSI (front) and 22 (back). Would this kind of numbers void my wheel warranty or,at least,increase the risk of rim damage?

    PS: I will soon change the tires (or at least the damaged one) to WTB Bronson 2.1 TCS (mounted tubeless with Stan's) if this makes any difference.

  99. #299
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    Problem i have is my regular ride features about 10 miles of road/paved tracks each way to and from the offroad stuff. Obviously you want higher pressures for the road and lower for offroad. I tend to try and find a happy medium which is about 30 front and 30-35 rear.

    If i'm driving to a trail i'll go 25-30 front and rear.

    Riding a 2.0 front and a 1.9 rear (both tubeless).

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    Aug 2012
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    180 lb rider 23 pound niner 23 psi 2.4 RR front 28psi RR rear tubeless

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