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Tubeless tyre pressure

defridedefride Posts: 277
edited July 2012 in MTB general
I've lurked a while here as I get back into riding after a couple of years out and just purchased a pair of wheels from the classified.

Its my first experience of Tubeless wheels and its started well. Tyres on and inflated without much bother. Will finally get a chance to ride them tomorrow. I'm planning on starting at 30psi and going down over the next few rides. Tyres are Spec Fasttrack LK 2.0. The riding? Cross country trails in the Chilterns so nothing extreme. Any comments on whether this sort of tyre pressure is a good start point welcome.

Cheers all
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Posts

  • Chunkers1980Chunkers1980 Posts: 8,035
    Depends how heavy you, your machine and equiptment are. 30 sounds like a good place to start though.
  • defridedefride Posts: 277
    Chunkers, thanks for the reply. I guess the following would be helpful in that case... I'm about 175lbs, hardtail Cube 25lbs-ish at a guess, XTR wheelset
  • Chunkers1980Chunkers1980 Posts: 8,035
    Yes 30 is a good place to start but depends on the terrain you are rinding on that ride, just like suspention it's a case of tuning it, 20 would be too soft for most, 40 is about that max, I'd say you'll end up between 25-30 psi for most things.
  • mrmonkfingermrmonkfinger Posts: 1,452
    I'd say you'll end up between 25-30 psi for most things.

    +potato
  • davewalshdavewalsh Posts: 587
    For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.
  • bennett_346bennett_346 Posts: 5,092
    davewalsh wrote:
    For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.
    :?

    Sounds like nonsense/witchcraft.

    Just set it to 25 and adjust as needed.
  • cooldadcooldad Posts: 32,601
    davewalsh wrote:
    For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.
    :?

    Sounds like nonsense/witchcraft.

    Just set it to 25 and adjust as needed.
    Especially if you are big enough to measure your weight in boulders.
    WTF is a stone anyway? Kg's I understand, even archaic things like lb's, but measuring in rocks?
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    davewalsh wrote:
    For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.
    I was about to call "nonsense", then I did the math, and, er... it may have some logic behind it after all. Witchcraft indeed :lol:
    Where did you learn this?
  • bennett_346bennett_346 Posts: 5,092
    By that calculation i should be running 15psi lol
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    By that calculation i should be running 15psi lol
    You must be pretty light then. Taking a 2.5" tyre (pretty damned wide) and using his formula, that would make you around 9+1/3 stone.

    And if you were that light, with a tyre that wide, then 15PSI might be fine.

    It's not as crazy as it sounds (although I'm not saying it isn't just a little bit crazy either :lol: )
  • YacobyYacoby Posts: 211
    9.5 * 4 / 2.2 = 18

    Waaay too low
  • bennett_346bennett_346 Posts: 5,092
    By that calculation i should be running 15psi lol
    You must be pretty light then. Taking a 2.5" tyre (pretty damned wide) and using his formula, that would make you around 9+1/3 stone.

    And if you were that light, with a tyre that wide, then 15PSI might be fine.

    It's not as crazy as it sounds (although I'm not saying it isn't just a little bit crazy either :lol: )
    It was a rough calc in my head, 10 stone * 4 = 40, / 2.3 = ~15 (17 with a calc).

    I'd never run it that low! It depends on what you ride and how rigid your tyres are etc.. But granted it isnt that far off ;)
  • supersonicsupersonic Posts: 82,708 Lives Here
    I have a better formula: 20 to 40psi. Or press with thumb, if firm, that'll do.
  • supersonicsupersonic Posts: 82,708 Lives Here
    And I have to say FastTrak tyres are the worst I have ever used. Ever!
  • cooldadcooldad Posts: 32,601
    I still don't know wtf a stone is in real terms.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Chunkers1980Chunkers1980 Posts: 8,035
    14 quid.
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    cooldad wrote:
    I still don't know wtf a stone is in real terms.
    Aren't you from that era, though?
  • cooldadcooldad Posts: 32,601
    cooldad wrote:
    I still don't know wtf a stone is in real terms.
    Aren't you from that era, though?
    Even in prehistoric times, in the colonies we used sensible measures divisible by 10.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • bennett_346bennett_346 Posts: 5,092
    cooldad wrote:
    cooldad wrote:
    I still don't know wtf a stone is in real terms.
    Aren't you from that era, though?
    Even in prehistoric times, in the colonies we used sensible measures divisible by 10.
    So stones then. 10 stone /10 = 1 stone.
  • cooldadcooldad Posts: 32,601
    cooldad wrote:
    cooldad wrote:
    I still don't know wtf a stone is in real terms.
    Aren't you from that era, though?
    Even in prehistoric times, in the colonies we used sensible measures divisible by 10.
    So stones then. 10 stone /10 = 1 stone.
    I was going to make a sarcastic remark, then saw Gateshead, and instead was overwhelmed by compassion.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • bennett_346bennett_346 Posts: 5,092
    cooldad wrote:
    cooldad wrote:
    cooldad wrote:
    I still don't know wtf a stone is in real terms.
    Aren't you from that era, though?
    Even in prehistoric times, in the colonies we used sensible measures divisible by 10.
    So stones then. 10 stone /10 = 1 stone.
    I was going to make a sarcastic remark, then saw Gateshead, and instead was overwhelmed by compassion.
    I'm flattered. Really, i am. It may surprise you to know that we have mathematics up here as well. Well, around 50% of us do. IIRC a lot of your family live in Sunderland which would make them Mackems, 90% of which haven't even got past primary school.
  • davewalshdavewalsh Posts: 587
    Where did you learn this?
    Stans website actually recommends dividing your weight in pounds by 7 then subtracting 1psi for the front and adding 2 for the rear, however this doesn't take into account the tyre width so I expanded it slightly.
    By that calculation i should be running 15psi lol
    Try it, you may be surprised :)
  • bennett_346bennett_346 Posts: 5,092
    I have tried it. Its virtually useless on thin sidewalled xc tyres on 30 mile rides. So i imagine it would be even worse if i was running tubeless.

    Maybe i run it a bit closer when im on the downhill trails, probably around 20 but i have thicker tyres for that so its irrelevant.
  • nicklousenicklouse Posts: 81,520 Lives Here
    anyway to answer the question a bit less than you would have used with tubes.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • davewalshdavewalsh Posts: 587
    edited June 2012
    I have tried it. Its virtually useless on thin sidewalled xc tyres on 30 mile rides. So i imagine it would be even worse if i was running tubeless.
    So you haven't tried it tubeless then.
    davewalsh wrote:
    For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.
    :?

    Sounds like nonsense/witchcraft.

    Just set it to 25 and adjust as needed.
    So, you dismiss my calculation as 'nonsense/witchcraft' then recommend exactly the same pressure as the calculation gives but without any logic or reason behind it :?
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    Well, come on. It IS witchcraft.
    If this was the dark ages, you'd have been burnt at the stake, or at least had a ride in the dunking stool by now :lol:
  • defridedefride Posts: 277
    Went out on 30psi today riding wheels that are much lighter than previously, the bike feels a great deal more skittish descending though not uncontrolably so. Climbs like a demon, I'm going up hills a couple of gears lower and took 20mins off my reg 1.40hr loop. Like the wheels, not sure on the tyres. Will try 28psi next time out.
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    defride wrote:
    Climbs like a demon, I'm going up hills a couple of gears lower
    :?
    huh?
  • bennett_346bennett_346 Posts: 5,092
    A lot of people seem to think "lower gear" refers to how low down the chain is on the cassette. Well, one person i know does.
  • YeehaaMcgeeYeehaaMcgee Posts: 5,740
    I bet they make terrible drivers :lol:
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