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Tyre Pressure

gareth.cantrillgareth.cantrill Posts: 33
edited February 2010 in MTB general
I'm riding about on a new Trek 8000. Happy as Larry with it but wondering what tyre pressure I need for pottering about my local trails. Obviously I'm new to riding.

The tyres fitted are Bontrager XDX, 2.2 on Bontrager SSR rims.

Posts

  • robertpbrobertpb Posts: 1,866
    How heavy are you?
    Now where's that "Get Out of Crash Free Card"
  • nicklousenicklouse Posts: 81,520 Lives Here
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The Big CheeseThe Big Cheese Posts: 10,309 Forum Tart 2010
    personal preference, I use quite high pressures on the hardtail, lower on the Fsuser...

    Experiment and find out what you feel comfortable with.
  • gezzzagezzza Posts: 324
    As low as you can get it with out hitting the rim or getting snake bit punchers if your still in the 19th century :wink:

    More grip and less rolling resistance win win
  • P-JayP-Jay Posts: 1,478
    gezzza wrote:
    More grip and less rolling resistance win win

    They're mutually exclusive when it comes to tyre pressures.

    Rolling Resistance increases as pressure drops.

    As for the OP, it's, as it's been mentioned, down to personal choice. I'd start with 35psi, if you find it's 'twitcy' drop it a bit, if it feels OK, try raising it a bit. That'll make it easier to pedal/roll.

    Then of course you can get proper censored like me and run different pressures front and back. As most of the weight is on the back (especially when climbing whilst seated) I run the rear quite hard. If I'm racing and there's a straight section I can shift my weight back and it was roll faster. I run the front softer, when cornering I've got my weight forward over the bars so need more front end grip. Also you can 'lose' the back easy and carry on, lose the front and 9 time out of 10 the first you know about it is you're on the floor looking up.
  • gezzzagezzza Posts: 324
    edited February 2010
    P-Jay wrote:
    gezzza wrote:
    More grip and less rolling resistance win win

    They're mutually exclusive when it comes to tyre pressures.

    Rolling Resistance increases as pressure drops.

    .

    I agree when your on road. off road how ever its not.

    Lower pressure lowers rolling resistance fact i run 22/25psi on RK 2.2's

    if you don't believe me how about Schwable? http://www.schwalbetires.com/wider_faster_page

    more indepth http://www.bicicletta.co.za/Downloadabl ... trated.pdf

    Try it out for yourself its quite a revelation
  • bomberesquebomberesque Posts: 1,701
    Basically what Gezza said but, while I'm not sure you can call the Schwalbe research that I read "proof" (therefore I don't really accept that it's FACT) it's certainly evidence that, counter to common sense, lower pressures can result in lower rolling resistance.

    All that said, I run 35 psi on basically all my MTB tyres. I'm not familiar with your tyres but some experimentation around that pressure will probably yield a favourite for you.

    watch out for squirming in corners and bottoming out on the rim (leading to pinch flats). These are signs that you need to up the pressure some more although pinchflats can be had at just about any pressure and path selection plays a part.
    Everything in moderation ... except beer
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    then riding a rigid singlespeed is like licking it
    ... or being punched by it, depending on the day
  • NorthwindNorthwind Posts: 15,475
    Basically what Gezza said but, while I'm not sure you can call the Schwalbe research that I read "proof" (therefore I don't really accept that it's FACT) it's certainly evidence that, counter to common sense, lower pressures can result in lower rolling resistance.

    Yup, well put, it's evidence but not proof.

    Now, pushing a wheelbarrow with a hard tyre, THAT's proof :lol:
    Uncompromising extremist
  • I used to race with 35F 40R, but now i'm 22F 26R, it allows you to ride so much faster.

    I know race times arn't back to back comparable, but i'll defo be sticking to the lower pressures, the bike rolls so much better over the ground.
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