Results 1 to 16 of 16
  1. #1
    mtbr member
    Reputation: RebelPro's Avatar
    Join Date
    Mar 2015
    Posts
    3

    Question about tires air pressure and trails...

    Hey everyone. Although I've been riding bicycle since I was a little kid, it wasn't until this past Sunday I rode a mountain bike went for a ride on an off-road trail for the first time. I must say I loved it and found it pretty challenging at times, but survived from falling (although I brought back home some bruises and scratches).

    Anyway, here's my question. When I bought my bike, the guy at the store suggested if I was to hit the trails, to lower the tires air pressure to avoid slipping and falling. I didn't really asked him how much, so I did as he suggested but I think I probably went a little beyond the appropriate (based on how I'm used to see on regular bikes).

    Anyway, is there a standard or reference I should follow? One, I don't want to make it easier to fall if the tires have too much air, and two I don't want to damage the tires if they don't have enough air.

    While I live in Miami and we don't have mountains here, the people who have worked on the trails have done an awesome job with obstacles and I think they could be rough, at least for me that I'm new to this.

    This is the bike, a 26" Specialized Hardrock
    Question about tires air pressure and trails...-img_1647.jpg

  2. #2
    R.I.P. DogFriend
    Reputation: jeffj's Avatar
    Join Date
    Jan 2004
    Posts
    5,999
    Lots of variables. Your weight, tire width, and rim width are among the most important.

    Easy answer: Start with 40psi. Lower it 2 psi per week until you get a pinch flat or the rear tire feels squirmy. Raise in 2 psi increments until you no longer get pinch flats or the rear tire no longer feels squirmy :~)

  3. #3
    since 4/10/2009
    Reputation: Harold's Avatar
    Join Date
    Dec 2003
    Posts
    13,789
    No standard. jeffj pretty much nailed the "easy" answer.

    On my skinny mtb (26x2.2-2.4), I tend to use about 22-23psi, tubeless, with tubeless ready tires that have stiff sidewalls.

    On my fatbike (26x4.0), I will run 2-9psi depending on conditions (2 psi, for example, in deep snow with higher pressure the faster I'm riding and the firmer the trails).

    On my commuter (700x38), I run about 60-65psi for pavement, and maybe go as low as 35-40 if I'm riding rough gravel, or postholed ice on the rail trail.

  4. #4
    mtbr member
    Reputation: RebelPro's Avatar
    Join Date
    Mar 2015
    Posts
    3
    Thank you @jeffj

    I think that's kind of the sensation I got from the rear tire, like if it was squirmy. I'll follow your instructions and see how that goes.

  5. #5
    mtbr member
    Reputation: Shakester's Avatar
    Join Date
    Jun 2012
    Posts
    1,229
    There is the talc or baby powder trick as well if you'll be running tubes. You can let the air out and and throw some baby powder in there. Seal it back up, give it a good spin to distribute and inflate. This will allow you to run lower air pressure while reducing your chances at getting pinch flats.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jan 2011
    Posts
    18
    ^^ never heard of that trick.

    Every ride I run a different tire pressure. Depending on the trail, trail conditions, tires, what I have in my pack, etc. I'm running Hans Dampfs this year on my chameleon. 26" tubeless.


    Sent from my iPhone using Tapatalk

  7. #7
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    110
    Quote Originally Posted by snowmobiler View Post
    ^^ never heard of that trick.
    Because it doesn't work. It'll make it a little easier to get tires out, but a little harder to patch if you flat. Urban legends die hard.
    I remember when I was a teenager...quiet hubs made me super nervous because I had a phobia of homosexual bikes.
    -AndrwSwitch

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    2,433
    Yeah, I never found it did anything for me.
    Sinister Bikes
    Wraith Bicycles
    Sunday River Mtn Bike Park
    NEMBA
    Wachusett Brewing Co.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Dec 2013
    Posts
    79
    The trick is to find what suits you, too low and you lose control / get pinch punctures / tyres come off the rims, too high again you can get less grip / more punctures / shaken around a lot. I run mine at about 40psi purely as it suits my riding.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Nov 2014
    Posts
    76
    Tire pressure is a lot of trial and error and varies with rim width, the tire sidewall (esp. tpi), tire width, tire volume, trial, rider weight and personal feel. You can also run lower pressure in the front than the back. Generally, the wider the rim, stiffer the sidewall, wider the tire, the lower the pressure can run. Tubeless allow lower pressures than with tubes. A lot depends too on how the particular tire plays with the rim. With tubes for 26" I'd start with 30 psi. Your Hardrock probably has 2.0 tires with a low tpi sidewall. That makes it sensitive to too low a pressure where it's prone to pinch flats and rolls. Start at 30 psi and ride. Air down the front a few psi and ride again. Repeat the process until you're happy with your set up generally. Your front tire is your control tire. You can run lower pressure in the front because more of your weight is on the back. The lower pressure allows more traction and control. Run about 5 psi less in the front. You can then start messing with it based on the trail conditions, but with tubes on a 26 x 2.0 tire a few psi more or less is not making a noticeable difference. Remember also that this all goes out the window if your tire pressure gauge is analog with +/- 5 psi margin since you'll be giving a good guess as to the pressure rather than spot-on pressure. Also use the squeeze test - if it feels too squishy it probably is. Make sure to ride with a mini-pump and spare tube, whatever pressures you're running. Have fun with the new bike.

  11. #11
    mtbr member
    Reputation: bigfruits's Avatar
    Join Date
    Mar 2011
    Posts
    851
    mtb.ubiqyou.com

    id do as mentioned by jeffj, start around 40 and work it down if you are running tubes.

  12. #12
    Mantis, Paramount, Campy
    Reputation: Shayne's Avatar
    Join Date
    Jan 2004
    Posts
    4,437
    Quote Originally Posted by noapathy View Post
    Urban legends die hard.
    Tires and tubes do get melted together...FACT
    Tubes do move inside tires...FACT
    Mr Brandt must not actually ride any of the wheels he knows how to build
    *** --- *** --- ***

  13. #13
    mtbr member
    Reputation: J.B. Weld's Avatar
    Join Date
    Aug 2012
    Posts
    3,047
    Quote Originally Posted by Shayne View Post
    Tires and tubes do get melted together...FACT
    Very true but mine always get changed long before that happens. I agree that using a little talc is technically optimal but in practical terms I've found it seems to make little difference. It definitely wouldn't allow me to run lower pressure or prevent pinches, talk can't stop a rim strike.

  14. #14
    mtbr member
    Reputation: J.B. Weld's Avatar
    Join Date
    Aug 2012
    Posts
    3,047
    And so far my experience with tubeless has shown me that the ideal air pressure is pretty much exactly the same whether using tubes or running tubeless, a rim strike is a rim strike.

  15. #15
    since 4/10/2009
    Reputation: Harold's Avatar
    Join Date
    Dec 2003
    Posts
    13,789
    Quote Originally Posted by J.B. Weld View Post
    And so far my experience with tubeless has shown me that the ideal air pressure is pretty much exactly the same whether using tubes or running tubeless, a rim strike is a rim strike.
    I've found the tire casing plays a bigger role with pressure than whether there's a tube or not. I'll agree, though, that with the same tire, I run the same pressure no matter if there's a tube. It feels a bit more supple when the casing flexes with a tubeless setup, but to avoid rim strikes, the same pressure does the job.

  16. #16
    mtbr member
    Reputation: Joules's Avatar
    Join Date
    Oct 2005
    Posts
    2,456
    Yes, there are a lot of factors, and yes it's personal... yet 99.9% of people end up in the high 20s to low 30s. Start at 30. You'll probably be fine there for a while.

Similar Threads

  1. How to determine tire pressure for fat bike tires?
    By motorider in forum Fat bikes
    Replies: 77
    Last Post: 2 Weeks Ago, 08:09 AM
  2. What pressure to run in mtb tires for cross?
    By stew325 in forum Cyclocross
    Replies: 5
    Last Post: 09-13-2014, 07:27 PM
  3. High pressure 26 x 1.5 tires on Stans 355?
    By TwigJumper in forum Commuting
    Replies: 1
    Last Post: 05-30-2014, 06:57 AM
  4. Taking pressure on presta tires
    By aan in forum Beginner's Corner
    Replies: 3
    Last Post: 08-14-2011, 01:04 AM
  5. High pressure pump for tires?
    By malariavalley in forum Wheels and Tires
    Replies: 2
    Last Post: 01-01-2011, 07:16 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •