Mountain bike tire pressure ranges from 25Psi to 40Psi. Depending on wheel and tire size, mtb recommended tire pressure should be varied by 5Psi for larger diameter.
All race tuning, from Formula One to Downhill, begins with an accurate tire pressure assessment, but it is important to remember that even causal riders will benefit from finding the ideal tire pressure to use.All race tuning, from Formula One to Downhill, begins with an accurate tire pressure assessment, but it is important to remember that even causal riders will benefit from finding the ideal tire pressure to use.
Every rider and tire combination has an air-pressure sweet spot, so use Pinkbike's inflation tips to find your perfect pressure and improve your shred.
Some tire-pressure must-knows...• Tire pressure is measured in PSI, which stands for
Pounds per
Square
Inch. It is a measurement of the pressure produced by one pound of force applied to an area of one square inch. Not that you need to know that to find your ideal tire pressure, but now you do!
• Invest in a hand-held digital or dial pressure gauge to check your tires and keep it in your gear bag. Pressure values vary significantly between floor pumps and you won't always be using yours.
• Use a series of taps on the air valve to release pressure in a controlled manner (
a small Allen wrench works well for Schrader valves).
• Write it down: Pro racers keep a written log of tire pressure, bike-fit and suspension settings, but you don't have to go that far. Write your starting pressures on the rim beside the valve with a Sharpie.
• Tire manufacturers emboss their sidewalls with minimum and maximum pressures that you may or may nor agree with--so consider yourself warned.
• Higher tire pressures do not always result in easier and faster rolling speeds. This is because a harder tire will want to deflect off of obstacles instead of letting the tire conform to the ground, absorb the impact, and roll over it without losing as much speed. Don't believe me? Picture yourself on a skateboard, rolling down a smooth road - you'll have no troubles. Now do the same thing on a rough road, or one with a bit of gravel on it, and you'll have much more trouble. This is because the skateboard's wheels are very hard and want to stop when they pass over even the slightest rough patch. This is why too much air can actually create more rolling resistance.
• Tire pressure is not only dependent on the type of tire you are using, but also the terrain that you're riding. Smooth and faster trails can be ridden with slightly more air pressure than a rougher trail. Taking the time to figure out what works best on the trails that you ride most often will only make your rides even better.
• Different tires, even of the same width, often work better at different air pressures. If you've switched to another brand or model of tire it will pay dividends to experiment with tire pressure, even if it is only a few PSI more or less than what you were running previously.
What's needed: tire pump, pressure gauge
Tire pressure is without a doubt one of the most important aspects of a proper setup. Watch the video to learn why:
Are you a Tire pressure King? Want to add a tip or hint of your own? Put it down below!
Past Tech Tuesdays:
Technical Tuesday #1 - How to change a tube. Technical Tuesday #2 - How to set up your SRAM rear derailleur Technical Tuesday #3 - How to remove and install pedals Technical Tuesday #4 - How To Bleed Your Avid Elixir Brakes Technical Tuesday #5 - How To Check And Adjust Your Headset Technical Tuesday #6 - How To Fix A Broken Chain Technical Tuesday #7 - Tubeless Conversion Technical Tuesday #8 - Chain Wear Technical Tuesday #9 - SRAM Shift Cable Replacement Technical Tuesday #10 - Removing And Installing a HeadsetTechnical Tuesday #11 - Chain Lube ExplainedTechnical Tuesday #12 - RockShox Totem and Lyric Mission Control Damper ModTechnical Tuesday #13 - Shimano XT Crank and Bottom Bracket Installation Technical Tuesday #14 - Straightening Your Derailleur HangerTechnical Tuesday #15 - Setting Up Your Front DerailleurTechnical Tuesday #16 - Setting Up Your CockpitTechnical Tuesday #17 - Suspension BasicsTechnical Tuesday #18 - Adjusting The Fox DHX 5.0Technical Tuesday #19 - Adjusting The RockShox BoXXer World CupTechnical Tuesday #20 - Servicing Your Fox Float ShockTechnical Tuesday #21 - Wheel Truing BasicsTechnical Tuesday #22 - Shimano Brake Pad ReplacementTechnical Tuesday #23 - Shimano brake bleedTechnical Tuesday #24 - Fox Lower Leg Removal And ServiceTechnical Tuesday #25 - RockShox Motion Control ServiceTechnical Tuesday #26 - Avid BB7 Cable Disk Brake SetupTechnical Tuesday #27 - Manitou Dorado Fork RebuildTechnical Tuesday #28 - Manitou Circus Fork RebuildTechnical Tuesday #29 - MRP G2 SL Chain Guide InstallTechnical Tuesday #30 - Cane Creek Angleset InstallationTechnical Tuesday #31 - RockShox Maxle Lite DHVisit
Parktool.com to see their entire lineup of tools and lubes.
But I must take issue with the claim about how a tire will lose pressure due to air leaking out the tube. I have 2 problems with this:
The explanation about how the air molecules will leak through the tube is wide of the mark. If you've ever seen helium party balloon you'll notice that they are always made of a metal foil (mylar) rather than the rubber/plastic of air balloons. In this case it's because a helium atom is extremely small/light and will actually diffuse through the material in the way you described. But air is mostly nitrogen and oxygen, both of which are relatively heavy diatomics, meaning that they won't diffuse through a thicker piece of rubber like an inner tube.
Secondly you can forget the chemistry and consider it empirically. You're trying to tell me that a ~40psi tire will initially lose 5psi a day? Then why is my 90psi BMX tire still happy after a month? Certainly you should always check pressure before a ride but if you're tire is losing that much pressure then you either have a slow puncture or a jammed valve.
Something not mentioned in the video is how pressure is dependent on temperature. You might have your perfect pressure set up in a nice warm workshop, but get your bike out in the snow and sub zero temperatures and the pressure will drop. Or if it's a sweltering day and you set up in air conditioning then be prepared for your tires to get harder as the air inside heats and expands. I couldn't say by how much but I'd bet it's measurable.
Believe it or not I hate to nitpick!
I weigh 60kg and I run 16psi on my Schwalbe Muddy Mary 2.5 (zero flats in 1.5months in the alpes 100% DH) and 12-14psi on the rear of my 24x3.0 contra. I run XC tubes by the way. I really dunno why anyone who doesn't weigh 100kg runs 30-40psi in their DH tires! though my french friends did flat using minions and DH tubes...
I remember reading about the tire pressure Nico Vouilloz used to run back in the day 22psi on Michelin 2.2 and he weighs 70kg. Wonder what the current World cup Pros are running...
2. I ran the Muddy Mary 2.5 DH casing with sticky compound at 16psi in the ALPES (Les Deux Alpes) for 1.5 months and NO flats (with a €2.5 26x2.1 XC tube)
4. Front rim was a 32mm (I'm now changing to a 42mm Trials rim so I can run 14-15psi)
5. for an examples of my riding check my photos OR www.youtube.com/watch?v=lJFVN75KwrQ
Matti's CRC Scalp running 24psi front tubeless and 27psi rear with Muddy Marys. Believe it or not! And he is running 28mm rims...
But I only run 12-14psi with a identiti contra (aka Duro 3.0 which is actually 2.
and hey guys, which is more pinch flat resistant? 2ply tire + regular tube or 1ply tire + dh tube?
2ply tire and XC tube is more pinch flat resistant even if it might not be lighter. I've tried both in the hope of shedding weight off the bike and forget DH tubes, totally unnecessary unless maybe you weigh 100kg.
Thanks,
Wes
Airwave tubes www.chainreactioncycles.com/Models.aspx?ModelID=41990
Schwalbe tubes www.chainreactioncycles.com/Models.aspx?ModelID=26726
I thought for years something mystic was going on with my notorious flatting. Then I learned that in my mountains if you ride "fast" you need a double ply tyre. For light tyres you need to go UST.
I agree, I want to know this too, there can't be that much of a difference can there.
Thanks for the reply,
I'm definitely not running too low pressure, still flatting with 50psi (yes I know that's crazily high but I haven't really mountain biked for a while). My last puncture was a thorn, not sure where the hole is though as its not leaking fast enough to find out
I'm running Mavic ex721's with 2.1 Nevegal ust tires (with tubes though)
My front wheel has an old inner tube between the tire and the tube (kenda) and the back wheel is running a Giant thornproof tube (which hasn't flatted at all, I've even cracked a rim with it on and its still been up)
And I'm about 55kg
Is the schwalbe worth the extra money or is it better to get the el'cheapos?
I would suggest fatter tyres too, latest research shows that 2,25 and fatter tyre rolls drives and grips better in than 2,1. Even roadies have to swallow the fact that even on smooth roads 25cm tyre is faster than super thin one. It was also shown that when road gets really rough, even CX category 32cm tyre provides better performance. It will take some time though for the old-school roadie "science" to die. They have also polluted XC a lot with their quest for holy performance and trying to limit variables which in fact are many even on their own backyard.
What about home made tubeless with 2ply tires? Do you recommend this combination or not.
I'm running a 2.5 maxxis 2ply on mtx33 with home made tubeless, do you think i"m doing a mistake,do you thing it will crash one day ,I got it over a year now and until now everything is fine.
thanks
Im 86kg and ride a XL Fury A spec.
In the past i have completly gone for 2ply sidewalls and light tubes! after testing all combinations.
Dh tubes only slow the bike down and make the tyres more bouncy, reduce control and rolling speed over bumps.
Now im testing Shwalbe big Betty´s (kevlar) with stan´s tubeless strip on a Mavic 729rim and it´s ligth and fast for a smooth track.
Im riding with a little more pressure than normal - 28psi up front but normally 25 - 27 on my Maxxis 2.5 high roller, swamp thing and wet scream´s also with cut knobs.
Last season i wrote only Maxxis Tubeless and love them but i find that on some tracks (little wet or very loose) the Continental Der Caiser´s can out perform the high roller´s, but for me the difference is minimal about 0,05-0,1sek...
But it is nessesary for me (possible for other´s) to go with even lower psi on the Der Caiser´s due to the thick sidewall´s.
Finding the rigth tyre pressure can even vary from season to season as rider´s get better and faster...
Im riding probably 2-3Psi less than last season due to my 9kg weigth loss this winter and that feel´s nessesary.
There is no clear line here tyre/tube/rim/style combinations vary allot.
Best thing is to go out and test what suites you personally and feels most planted to the ground without the tyre folding to the side in hard corners.
Cheers guy´s and good luck getting faster!
Anyway I keep a log of the date I ride and the tire pressure used that day, once I feel confortable in a ride, I mark the setting and try to keep it.
en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure
I personally run about 35 psi, but never really paid much attention to it. After watching this I'm going to keep a closer eye on it.
Quote: Im going to call BS on 15 psi. Normal air pressure levels are 14.5-14.7 or so, so theres no way you would get any inflation at all at 15.
That is partially correct. Atmospheric pressure (one bar) is around 14.7 psi at sea level, as you stated, but tire pressure is measured as if ambient pressure is zero. So running 15psi in your tire (or air shock) at sea level would actually be 29.7psi. Your gauge, however, will still read zero at whatever pressure altitude you begin pumping. Up at 8,000 feet above sea level, atmospheric pressure is only 10.88 pounds per square inch, but inflating your tires to 15 psi will feel the same as 15 psi does at sea level because the pressure differential is 15psi above ambient atmospheric pressure