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  1. #401
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    Tire pressure for all around XC riding?

    Quote Originally Posted by XTERRAGreg View Post
    Guess i have been on road/TT bikes too long... I still have a "mental" issue going below 30psi on my tubeless setup.. All I can think about is rolling resistance.
    Doesn't increasing the pressure increase the rolling resistance? Since when you hit an imperfect part in the road it forces the tire to push up into the bike instead of the tire conforming to the road.

    Am I wrong?

  2. #402
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    Quote Originally Posted by Givmedew View Post
    Doesn't increasing the pressure increase the rolling resistance? Since when you hit an imperfect part in the road it forces the tire to push up into the bike instead of the tire conforming to the road.

    Am I wrong?
    you are correct.

    I run TT on road and there is one 10 miler upstate NY which is fresh paved and almost zero road imperfections (occasional cow pies that is it) I run >180psi on that road and get my best TT times. if I run these boneshakers anywhere else where there are cracks it not only annoys me but does seem to slow me down, so I use 120psi everywhere else

    there is always sweet spot between: too low pressure and obvious wasted effort, a conforming and optimal pressure for the road/trail conditions, and high pressure where bouncing and deflection robs you of forward watts

  3. #403
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    and of course in mountain biking correct tire pressure can often be the difference between riding and walking. too high or too low can cause this to happen but especially in technical singletrack lower pressure can be a huge benefit

  4. #404
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    Tire pressure for all around XC riding?

    Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40

    I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.

    So I just let him do it.

    Anyways

    Was he right since maybe he knew more about the track than me?

    It was mostly dry and very packed dirt/clay. Smooth and hard with a few nasty mud pudals in the low areas. There where some tree roots that you hit hard and some come at the tire from the side.

    What if anything did I gain from increasing the tire pressure that high and what did I loose?

  5. #405
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    Quote Originally Posted by Givmedew View Post
    Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40

    I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.

    So I just let him do it.

    Anyways

    Was he right since maybe he knew more about the track than me?

    It was mostly dry and very packed dirt/clay. Smooth and hard with a few nasty mud pudals in the low areas. There where some tree roots that you hit hard and some come at the tire from the side.

    What if anything did I gain from increasing the tire pressure that high and what did I loose?
    First, 30 front and 25 rear is the opposite of what you should have, rear takes more pressure normally.

    What you get with higher pressure is pinch flat resistance, better rim protection and stability in turns.

    What you loose is traction mostly. Especially over sideways impacts, the tire will bounce to the side instead of deflecting around the side impact.

  6. #406
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    Tire pressure for all around XC riding?

    Quote Originally Posted by CrozCountry View Post
    First, 30 front and 25 rear is the opposite of what you should have, rear takes more pressure normally.

    What you get with higher pressure is pinch flat resistance, better rim protection and stability in turns.

    What you loose is traction mostly. Especially over sideways impacts, the tire will bounce to the side instead of deflecting around the side impact.
    I just assumed that having front suspension meant it was ok to have a higher front pressure. The bike is a hard tail.

    I am running tubeless and pinch flat is tubes right?

    Also I do weigh 210LBs if that matter and tend to keep my but on the seat most of time.

    Is 25LBs too low? Should I actually be running a higher pressure in the rear than the front?

  7. #407
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    Quote Originally Posted by Givmedew View Post
    Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40

    I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.

    So I just let him do it.

    Anyways

    Was he right since maybe he knew more about the track than me?

    It was mostly dry and very packed dirt/clay. Smooth and hard with a few nasty mud pudals in the low areas. There where some tree roots that you hit hard and some come at the tire from the side.

    What if anything did I gain from increasing the tire pressure that high and what did I loose?
    He was wrong.

    By having less pressure in the tyre, you increase the contact patch which means more traction & braking (longitudinal force) and cornering (sideways force). This is ALWAYS true (simple physics).

    However, once you get tyre pressure too low you suffer 2 consequences - one that everyone talks about, and the 2nd one that most don't. The first one is pinch-flats - these CAN be an issue but not if you run tubeless - then you might get a "burp" when the sidewall loses sealing. The 2nd consequence is loss of cornering precision, particularly if the front is too low. A squirmy front end doesn't help XC speed.

    I weight 90kgs and run front and rear between 25 to 30 psi depending on the conditions. Looser, then I go lower, harder then higher.

  8. #408
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    Givmedew, just use what feels right. There is no magic numbers to chase. Each tire response is different and each riders riding stye is different. I do ride with the front tire inflated about 5 lbs more somtimes because it just works for me. If your buddy is a good rider and has been riding for twenty years then as a beginner that a great place to start. I hope your liking the dirt side on two wheels.

  9. #409
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    Tire pressure for all around XC riding?

    Quote Originally Posted by redd4573 View Post
    Givmedew, just use what feels right. There is no magic numbers to chase. Each tire response is different and each riders riding stye is different. I do ride with the front tire inflated about 5 lbs more somtimes because it just works for me. If your buddy is a good rider and has been riding for twenty years then as a beginner that a great place to start. I hope your liking the dirt side on two wheels.
    There is no way I am going to be able to judge what feels right the first time on the bike. The tires recommendation is very broad.

    To my friend riding for 20 years...

    He doesn't pretend to be a pro. But I know people who have done things their whole lives the wrong way. I am a very technically minded person and am always mindful of every little thing.

    The tire recommends up to 65 pounds. I reading people running as low as 20LBs. When I went on a demo ride of a RIP 9 NINER a few months back someone on the ride with a tubeless had exactly what someone was describing where suddenly the tire went completely flat.

    Just trying to wrap my head around an entirely new world for me.

    Going off my butt dyno isn't going to work the first ride or even the first year of riding.

  10. #410
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    Cool-blue Rhythm

    After reading all this I dropped from 30 psi front and rear to
    28 rear
    26 front

    No pinches, less root skipping and a bit more side bite in the smooth stuff.
    Running Rocket Ron's 27.5 and full suspension.
    I'm 185 with 100 oz's of water and gear in my Camelbak volt and ride gear, bike Is at 30 pounds :P

  11. #411
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    Quote Originally Posted by Osco View Post
    After reading all this I dropped from 30 psi front and rear to
    28 rear
    26 front

    No pinches, less root skipping and a bit more side bite in the smooth stuff.
    Running Rocket Ron's 27.5 and full suspension.
    I'm 185 with 100 oz's of water and gear in my Camelbak volt and ride gear, bike Is at 30 pounds :P
    I run that pressure and I'm 210 and on a 29er HT. High volume tires though, 2.3"+and tubeless

  12. #412
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    Tire pressure for all around XC riding?

    I run my tires so that they bulge a little bit when I look straight down at them, while on my seat. Seems to work so far

  13. #413
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    Re: Tire pressure for all around XC riding?

    Quote Originally Posted by nauc View Post
    I run my tires so that they bulge a little bit when I look straight down at them, while on my seat. Seems to work so far
    I run my stomach that way too...

  14. #414
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    just to add ....... since I perfectly dialed it all in.

    I ride a TREK EX7, I weigh 155 w/ all my gear

    Tubeless Setup - 29er

    Hans dampf Front - 18 psi (2.35)
    Nobby Nic Rear - 20 psi (2.25)

    Works flawless and I ride a lot of XC and do some fairly steep climbs and FAST downhill trail runs (no boulders).

  15. #415
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    tire pressures mean nothing unless you post complete tire size

    a 26 inch 1.9 35psi feels the same as a 27.5 2.4 at 25 psi as far as firmness and
    bounce on trail (to me anyway)


    so, all these pressures in this thread, if there is not the fatness of tire listed it is not that informative.

    vredestein black panther extreme TLR 27.5 2.2 inch 25psi feels about right for XC chunder

  16. #416
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    Re: Tire pressure for all around XC riding?

    Quote Originally Posted by 127.0.0.1 View Post
    so, all these pressures in this thread, if there is not the fatness of tire listed it is not that informative.
    Also the width of the rim and whether tubed or tubeless...

  17. #417
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    Tire pressure for all around XC riding?

    17-20psi in my NobbyNic 2.35s on Derby 29er rims. Tubeless. Hardtail in the Alps. I weigh 185lb.
    M

  18. #418
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    I run tubeless 27.5 with 2.3 High Roller II tires on ENVE AM rims...For long climbs or flat xc riding I usually air up to about 35psi rear and 32psi front.

    For long descents I air down to about 28-25psi in the front and about 30psi in the rear. Anything less and the tires start to get squirmy in turns.

    I have gotten snake bites in the actual sidewall of tubeless tires when running to low of air pressure and start banging rims on rocks. Don't know how people running 20 psi in the rear tire don't thrash their tires and rims, maybe on buff single track thats ok.

    When airing down the tires at the top after a long climb I do the squeeze test on the tire and go by feel.

    Pressure depends on your tires, bike setup, riding style, personal preference, and terrain. There is no right or wrong answer. Play around with different pressures and find whats right for you.

  19. #419
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    In praise of higher tire pressure - I ran 40 psi (highest safe pressure on Stan's rims per Stan's) just because I was too lazy to tune the pressure after doing a road ride with my son.

    With the trails dried out -- WOW! Yes, I gave up some traction, and, no, these are not technical trails besides some roots. What I gave up in straight line traction I made up for in fast turning on the tight corners built into these trails. So much fun and so responsive.

    It's not a setting I'd use all the time, but on trails I know with hard conditions, it was fun!

  20. #420
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    I ride a 29er FS Trek Superfly on XC trails that have a few rocks and I run the pressure on front and back at around 22 to 30 psi with tubeless ready tires. 1.95 - 2.2 sized tires. Rarely go above 30 psi unless I plan on riding mainly on the road/paved path.

  21. #421
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    On my Scott Spark 27.5, I am 190 lbs In ride gear and a full pack.
    Rims are 24mm O.D. and I think 20mm I.D.

    I don't have sharp rocks but I got roots of all shapes n sizes.

    Running 2.25 Rocket Ron's tubed, at 28 rear 27 front I don't pinch.
    Any lower and I get squirmy In turns. Above 30 psi front or rear and I skip off things.
    I don't care to go tubeless but with wider rims I may

    I am wanting wider rims, say 30-35mm O.D.,, 25-30mm I.D.
    My Motocross background tells me wider rims are a smart mod.

    Just saying...

  22. #422
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    Re: Tire pressure for all around XC riding?

    26x2.3 X-Kings on 18mm id rims (rigid single speed).
    20r/16f is good for the bumps, but as I found today, it's easier to (almost) roll a tyre at 16psi.
    21r/18f may be safer...

  23. #423
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    Tire pressure for all around XC riding?

    while sitting on my bile, looking straight down at my tires, i let out enough air, so the tires bulge a little bit. no idea what psi it is, dont care

  24. #424
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    Quote Originally Posted by nauc View Post
    while sitting on my bile, looking straight down at my tires, i let out enough air, so the tires bulge a little bit. no idea what psi it is, dont care
    You sir are hardcore, well played.

  25. #425
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    When I got my MTB, the bike shop set the pressure at the recommended 50 psi (according to Continental's website) which was fine at the time given the local MTB trail was closed and I was limited to pavement the first few rides. However, I did notice once the trail opened up the back end felt a bit loose when I'd accelerate so I'll be dialing the pressure down. Don't want to get to the point where I pinch flat though, I ride my bike to the trails since I live so close and bringing a floor pump to play with tire pressure really isn't an option for me. Maybe start at 35/40 psi and go from there? I am running tubes, just starting MTB coming from road so I want to see how much I like this (so far so good) before I start laying out money for better wheels and going tubeless.

  26. #426
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    MIT Formula

    An MIT professor assigned this issue to his class and they came up with the following formula, where x=rider weight, y=wheel size and z=tire width.

    x times y divided by z times .01 (1 percent)

    This assumes tubeless.

    So a rider weighing 185 riding 29er on 2.2 tires would run 24 psi.

    A rider weighing 210 riding a 27.5 bike on 2.35 tires would run 25 psi.

    A lightweight rider at 165 on a 26er and 2.1 tires could get by with around 20 psi.

    Note that this applies to overall riding, not strictly XC. It is a general rule of thumb as well, since the MIT team could not factor in such unquantifiable variables as riding style, surface type and rider intelligence, although they did suggest that the higher the IQ, the less applicable the formula is...
    All bike, all the time

  27. #427
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    Re: Tire pressure for all around XC riding?

    Quote Originally Posted by BikeIntelligencer View Post
    An MIT professor assigned this issue to his class and they came up with the following formula
    Finally! I don't know how mountain bikers have gotten by all these years without a bunch of MIT students using a math model to tell them what tire pressures to run.
    Quote Originally Posted by BikeIntelligencer View Post
    x times y divided by z times .01 (1 percent)
    All those brains and they ended up with a simple linear relationship? Boooo. If you're going to overcomplicate something you might as well do it right.

    Btw, what does this formula attempt to optimize? Rolling resistance? Traction? Feel?
    Quote Originally Posted by BikeIntelligencer View Post
    although they did suggest that the higher the IQ, the less applicable the formula is...
    Because if you have a brain you know to ignore such a silly formula?

  28. #428
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    I would expect MIT guys to know a simple fact that the pressure on the front and rear is different, so there should be two separate formulas for front and rear (just by another simple fact that there is more weight on the rear). Other formulas already account for that, so that's not exactly rocket science.

    How many students passed this class? Actually what class was it?

  29. #429
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    Cool-blue Rhythm

    Quote Originally Posted by Scottwax View Post
    When I got my MTB, the bike shop set the pressure at the recommended 50 psi (according to Continental's website) which was fine at the time given the local MTB trail was closed and I was limited to pavement the first few rides. However, I did notice once the trail opened up the back end felt a bit loose when I'd accelerate so I'll be dialing the pressure down. Don't want to get to the point where I pinch flat though, I ride my bike to the trails since I live so close and bringing a floor pump to play with tire pressure really isn't an option for me. Maybe start at 35/40 psi and go from there? I am running tubes, just starting MTB coming from road so I want to see how much I like this (so far so good) before I start laying out money for better wheels and going tubeless.
    This happens to many new riders I bet, bike shop going for lots of psi.

    I'd say a baseline starting point for a 200 pound rider including full gear on any 2.2" or up tire in 26, 27.5, 29er tubed and not riding really big hits in rock gardens should be 30 psi front and rear. Ride that for a whole day, carry TWO tubes, pump and tools.

    Next ride drop two psi at each end and see what you feel, ride that for two full rides, go by feel, handling.
    Too much air makes my bike feel disconnected, jittery, The back end skips off roots kicking the rear about some this way or that.
    I actually feel the front tire difference the most when dropping/leaning into a corner.

    I'm down to 26 psi front and rear now. No pinches, feels better.

    Now at this psi, the change in feel by dropping just one more pound of air was so profound I am ready to go tubeless...

    Still gonna carry a tube.
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  30. #430
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    About your tire pressure

    The pressure depends on some reason:
    1.your weight;2.the temperature 3.Stiffness and structure of your bike rims

    suggest no more than 40 PSI if everything is in normal.

  31. #431
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    Quote Originally Posted by Osco View Post
    This happens to many new riders I bet, bike shop going for lots of psi.

    I'd say a baseline starting point for a 200 pound rider including full gear on any 2.2" or up tire in 26, 27.5, 29er tubed and not riding really big hits in rock gardens should be 30 psi front and rear. Ride that for a whole day, carry TWO tubes, pump and tools.

    Next ride drop two psi at each end and see what you feel, ride that for two full rides, go by feel, handling.
    Too much air makes my bike feel disconnected, jittery, The back end skips off roots kicking the rear about some this way or that.
    I actually feel the front tire difference the most when dropping/leaning into a corner.

    I'm down to 26 psi front and rear now. No pinches, feels better.

    Now at this psi, the change in feel by dropping just one more pound of air was so profound I am ready to go tubeless...

    Still gonna carry a tube.
    Yeh carry a tube even if your running tubeless. Or at least bring it with or make sure someone has a tube. I make sure someone in our group has a tube and co2 inflator or pump.

    I don't carry 2 unless I'm going far. If your going 10-20 miles from your car then sure 2 tubes for a group of 2-4 riders but if your only going to be 1-3 miles I would just make sure 1 tube is available. It doesn't matter what size it is either. If someone has a 26 w/ them that's enough.

    I've never had a tubeless fail but it does happen. If I did a century id cary 2 with and my own pump or atleast an adaptor for my shock pump.




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  32. #432
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    Funnily enough, I've been riding tubeless recently and it's scary to me just how low I've had to go to stop feeling like I'm being bounced around all over the place.

    Right now I'm running 20 up front and 24 on the rear.

  33. #433
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    My Hutchy Python's had a sweet spot around 24f/26r whereas the Mich Wild Rac'r Advanced Ultimates needed to be around 20f/22r for the same feel.
    The Hutchy's have great pedaling traction and a nice ride, the Miche's only downfall is cornering, braking and acceleration.

  34. #434
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    Quote Originally Posted by NordieBoy View Post
    My Hutchy Python's had a sweet spot around 24f/26r whereas the Mich Wild Rac'r Advanced Ultimates needed to be around 20f/22r for the same feel.
    The Hutchy's have great pedaling traction and a nice ride, the Miche's only downfall is cornering, braking and acceleration.
    So your review on the wild racer would be

    Title: the tires didn't explode... Yet

    Pros: So these tires went fit onto a rim that they where supposed to fit. They have labels so you don't accidentally mix them up with a better tire. They are made from rubber.

    Cons: When turning the front washes out and the rear slides. When accelerating uphill the tire spins excessively. When braking the front locks up quick and the rear is mostly useless.

    If the purpose of these tires where to protect the rims from scratches while on the show room floor they NAILED IT 5-Stars!


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  35. #435
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    The Wild Rac'r is light. Very light.
    Very good for trail braking into and around corners.

    At the speed I race at, it's actually a pretty good tyre.

  36. #436
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    Quote Originally Posted by NordieBoy View Post
    The Wild Rac'r is light. Very light.
    Very good for trail braking into and around corners.

    At the speed I race at, it's actually a pretty good tyre.
    Lol good one

    Same back handed comment car and driver gave the rali art...
    Car sucks but once you get used to trail braking it then its kind of fun to drive in a pitch and catch kind of way. (Think that was close to their exact words)


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  37. #437
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    Quote Originally Posted by NordieBoy View Post
    the Miche's only downfall is cornering, braking and acceleration.
    I just got a set of 29 er Wild Race'r advanced Gum X 2.25 . Haven't had a chance to try them out but they look fast, wider than 2.25(compared to my Racing Ralph 2.25) and they feel very light.

    The main qualities I look for in a tire are - cornering, braking and acceleration, so your review has me concerned. I mean what else does a tire do if not these 3 important things?

    I guess rim protection is highly rated by some LOL!

  38. #438
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    Mine were the 26" Advanced Ultimate. Ultra light, but a sidewall cut means I have to run tubes which defeats the idea of a nice light, responsive tyre.

  39. #439
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    Cool-blue Rhythm

    Current setup,
    Scott Spark 760

    185 pounds in full ride gear.

    27.5 X 2.25 Rocket Ron out back, tubed 25 psi feels great, no pinches.
    a 500ish gram tire.

    27.5 X 2.35 Bonty XR-3 front, tubed at 23 psi,,, feels great, no snake bites yet
    a 700ish gram tire.

    Lower than this gives me a squirmy ride, lowest tested so far 23 rear, 21 front, tubed.
    “I seek only the Flow”, "27.5+ Hard Tails Rock"
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  40. #440
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    Up until today I had always been old school and ran 2.0 to 2.1 tires. Today my 26x2.4(actual 2.33) maxxis ardents arrived and I have to say. I'm a high volume casing convert. I use them on the front at around 28psi and it was amazing what a difference it makes going over rocks and roots at speed. I have 2.1 Ignitors on the back and once they run out of tread in getting 2.2 or 2.3s. It makes such a difference. Now I see why people like high volume casing. It absorbs so much.

  41. #441
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    65 kg rider, 13 kg bike, 27.5"×2.1" Kenda Kadres with tubes, 19/24 psi, no pinch flats yet, even survived a little drop.

  42. #442
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    I weigh 160 lbs. Specialized Pitch 2015.
    Specialized FastTrack 650b, 2.0" tires front and back.
    Both at about 23 psi. Ride mostly xc trails. So far no flats after several months.

  43. #443
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    How low pressure could I possibly go?
    I weigh 115 pounds and my bike weighs around 30.
    I'm running continental 26x2.2" tires tubeless W/ Stan's on my hardtail that has an 80mm fork.

  44. #444
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    Quote Originally Posted by shiggy View Post
    Well said!
    Indeed! Terrific advice!

  45. #445
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    20/22 front rear on stock tires and tubes. Want to run lower but getting some rollover squirm. Maybe tubeless next?
    2015 Giant Trance 3
    X-Fusion Sweep RL2 160mm fork
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  46. #446
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    Quote Originally Posted by noose View Post
    20/22 front rear on stock tires and tubes. Want to run lower but getting some rollover squirm. Maybe tubeless next?
    Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.

  47. #447
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    Quote Originally Posted by J.B. Weld View Post
    Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.
    Well my HD 2.35 trail star for the front should be here tomorrow. Maybe I'll get something else for the back too. I would love wider rims but may have to wait for a while.

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  48. #448
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    Quote Originally Posted by J.B. Weld View Post
    Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.
    So far 18 psi is working fine on the new HD TS on the front. No squirm and much more grip than the NN Performance it replaces. The rear NN Performance really can't keep up now so I ordered an HD TS SG for the back and going tubeless too. Tubeless and thicker sidewalls should help with rollover and pinch flats I am bound to get running around or just under 20 on the back.
    Last edited by noose; 05-15-2016 at 05:26 PM.
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  49. #449
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    I'll just add this
    175lbs with gear
    2015 FUEL EX9
    Bontrager Rhythm Comp tubeless
    Bontrager XR3 experts 2.3 front and rear

    Took my bike in for some work, they trued my wheels and replaced valve stems. Got the bike back, go for a ride, terrible. Felt every root, every bump, spinning the tire trying to climb, and worse yet, wiped out 3 times on slower turns.

    Get back from my ride, check pressure, they had me set at like 35psi. Dropped it to 25psi, went back out, and it was smooth as could be, quiet, tons of traction everywhere.

  50. #450
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    Quote Originally Posted by Tillers_Rule View Post
    Historically:

    50F/50R
    35F/45R

    Now I'm at 35F/40R. I've found anything less in the rear and the tire distorts too much, I can go a bit less in the front but this combo seems ideal for me for now. I'm 215 loaded up. Picking up a new bike here, a 29", so I'll get to play with PSI again!
    Interesting looking back and what I was riding with almost exactly 4 years ago.

    Since then I got the RIP9 and put the 26'r to the side collecting dust. Cleaned it up a couple months ago, threw some wider handlebars on it and dropped two of the front chain rings (would only ever use the middle ring).

    PSI for my Niner is usually ~34R and 31F. Now that I'm back on the 26'r I've been playing with it's PSI, last time I think I was at 41R and 34F.

    My riding has improved and style has changed. I used to just blast through the trails as fast as I could. Now we jump, try out skills at balancing, work on sections, etc.

  51. #451
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    I weigh 235lb's in my birthday suit...

    I also advocate for the tyre determines the required pressure.

    2.4's I've run in the past @ 22-24psi... 2.35's = 23-25psi... 2.3's = 24-27psi... 2.2's = 28-30psi...

    Plus I run tubes... I get a flat once a year, on average. I run protection variety tyres only. Little extra weight for peace of mind.

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    Last edited by targnik; 08-19-2016 at 04:29 PM.
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  52. #452
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    Quote Originally Posted by Osco View Post
    Current setup,
    Scott Spark 760

    185 pounds in full ride gear.

    27.5 X 2.25 Rocket Ron out back, tubed 25 psi feels great, no pinches.
    a 500ish gram tire.

    27.5 X 2.35 Bonty XR-3 front, tubed at 23 psi,,, feels great, no snake bites yet
    a 700ish gram tire.

    Lower than this gives me a squirmy ride, lowest tested so far 23 rear, 21 front, tubed.
    I'm the same weight as you and settled in at the same pressure on tubeless HD trailstar front and same tire but in Supergravity on the back. Pleased with grip and ride quality over the rough stuff.

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  53. #453
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    Quote Originally Posted by Gregon2wheels View Post
    In praise of higher tire pressure - I ran 40 psi (highest safe pressure on Stan's rims per Stan's) just because I was too lazy to tune the pressure after doing a road ride with my son.

    With the trails dried out -- WOW! Yes, I gave up some traction, and, no, these are not technical trails besides some roots. What I gave up in straight line traction I made up for in fast turning on the tight corners built into these trails. So much fun and so responsive.

    It's not a setting I'd use all the time, but on trails I know with hard conditions, it was fun!
    I run pretty much max pressure of whatever tire im on. Currently Ikon 26 x 2.35 @ 60psi and in my experience the skitish behavior of high psi can be overcome by smooth body control and good sense. I do give up some bite on climbs and on some of the hairy corners I take them a bit slower but everywhere else, i'm flying way faster with the increased pressures and not having to pedal so much to maintain speed either. I put down a fair bit of mileage each year and the added bonus of almost never flatting out from tubes and high psi is a double bonus on a 100mile tour. I fly over roots and rocks and hang on tight, set the suspension on the soft side with lots of rebound control to do the job it was made for instead of relying on the tires as springs.

    Different strokes for different folks.

  54. #454
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    Wow.
    I'd consider 24psi as far to high for a front 26x2.35 Ikon.

  55. #455
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    LOL! That's a bit like the guy over in the Specialized forum that said his 29x2.3 Fastrak (which actually measure out to a shy 2.2 btw) felt 'supple' at 2 bar (29psi) and his 71kg (156lbs)...

    supple he said...

    Anyway, not to discredit urban commando...what happened to the data that said that lower pressures actually attributed to faster times because the tire wasn't being deflected as much?

  56. #456
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    I figured that post would pop some eyes open and invite the hecklers. Theres nothing supple about my set up thats for sure. Its skittish, but its fast and durable. Also worth noting on loose gravel the high psi is BRUTAL for wash outs around corners, thats probably where they are at their worst. On dirt or even mildly wet loose dirt its a handful but manageable and fun too. I also really like the nevagels @ 50psi on loose terrain they corner excellent, climb and roll quite well but only when its loose. Those tires are slugs on hard surfaces imo. Also in the 2.35 btw.

  57. #457
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    I'm not meaning to heckle you urban commando. Your post just reminded me of that other one. Actually the way you commented about it, relayed effectively that you were dialing the suspension to help compensate and that it was still a compromise.

  58. #458
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    i run 35 rear 30 front with 2.3 geax sturdy's on my hardtail

  59. #459
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    Quote Originally Posted by omarlin29 View Post
    i run 35 rear 30 front with 2.3 geax sturdy's on my hardtail
    How much do you weigh? 250?

  60. #460
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    Quote Originally Posted by NordieBoy View Post
    26x2.3 X-Kings on 18mm id rims (rigid single speed).
    20r/16f is good for the bumps, but as I found today, it's easier to (almost) roll a tyre at 16psi.
    21r/18f may be safer...
    I want to run 16f/20r but am worried about rolling the tire right off the rim. I run 20 and 23 right now without squirm at slower speeds but am riding faster trails starting in the spring.
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  61. #461
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    Interesting that he is running very close pressure to me. Much faster though which increases my confidence that I won't lose a tire. https://youtu.be/RnoA05c-_os
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  62. #462
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    Hi, with 220lb ( bicycle + me) and 2.35 tire, i run 21.2f/23.4r for xc, and 24.9f/27.5r for smooth rolling on good roads.
    I use this android app that calculates pressure with 15% or 18% drop. https://goo.gl/0laa5O

  63. #463
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    Quote Originally Posted by tramuntana View Post
    Hi, with 220lb ( bicycle + me) and 2.35 tire, i run 21.2f/23.4r for xc, and 24.9f/27.5r for smooth rolling on good roads.
    I use this android app that calculates pressure with 15% or 18% drop. https://goo.gl/0laa5O
    23.4? That's crazy! No less than 23.6 for me.
    I brake for stinkbugs

  64. #464
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    I haven't read all of the posts in this thread so I apologize if this has already been discussed...

    I've found that comparing tire pressures are problematic, given that tire pressure gauges give such a wide range of pressures. Your gauge may say 24psi and mine could read more or less.

    I had two gauges of the same brand that I purchased at the same time and one read 3-4psi more than the other. Which one was correct? Where either of them correct?
    Never be afraid to try something new.

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    Professionals built the Titanic.

  65. #465
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    most likely neither was correct. You should just use one of them, figure out what pressure works best for the trail on that day and in those conditions, and you will constantly have to adjust for each ride (especially as ambient temperature changes so much). It may seem stupid or not precise enough to grab your tire and squeeze, but because gauges vary so much you should try to memorize how your tire feels at your ideal pressure, so then you can use that as a rule of thumb when using other pumps.

  66. #466
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    I weight 210lb/95kg, ride i27 rims, use 20 psi rear and 19 psi front with Conti RaceKing 2.2 tires in tubeless configuration.
    With the previous i19 rims I had to use much higher pressures to prevent the annoying tire rollover effect

  67. #467
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    Unique formula for me.

    Find some edge block... or sharp rock in that shape .^.

    -Lock out front fork
    -Put front tire on midle of rock
    -Press front brake on max
    -Holding handlebar - squeeze that front tire on peak of rock-block or whatever.
    -Push That tire as max as as u can on that rock.

    And set preasure, on that level, where u are able with all your strenght to squeez front tire not more than half off travel to edge of wheel. This will be preasure for all around.

    For max grip and downhill go on 80% of that travel... if u belive in your wheelset and tires ... and if trail is not sharp rocky and u have tubeless go on 90% or even more of travel. But be ware

    For rear preasure add around 15% more psi/bar than on front.

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