Viewing 14 posts - 1 through 14 (of 14 total)
  • What Psi for Hopton Woods
  • Premier Icon shinsplints
    Free Member

    I’m riding there tomorrow on a 29er. I usually like to run around 30 in the back & 25psi in the front, but I don’t want to have any accidents as 29ers ridden at the wrong Psi can be a right handful.
    What does any one else do ? I don’t want to ruin my day.

    Premier Icon thisisnotaspoon
    Full Member

    Depends on the phase of the moon and state of the tide, if there’s a full moon you need to account for the additional solar heating especialy with no cloud cover. And shortly after slack water the extra gravitational pull of 29er wheels can cause issues if run too high that they cant slip to account fo this.

    Premier Icon shinsplints
    Free Member

    You see this is what I am worried about.
    Good thing is Hopton is not far from my house so I can always go home & re-fettle the bike again, before heading back out.
    Thanks thisisnotaspoon.

    Premier Icon ssboggy
    Full Member

    Doesn’t really matter as the wheels will probably explode before and psi induced accidents 😉

    Premier Icon grum
    Full Member

    I find 25 PSI on the front totally unusable. If you lower it to 24.6 you get infinitely more grip. That’s on 26″ wheels though so it could be totally different on a 29er.

    Premier Icon shinsplints
    Free Member

    Is there a sheldon brown type calculator for 26″ wheel psi / 29″ wheel psi ?
    Grum, no way. I rode my 29er at Dyfi Forest once at 24.8 psi & went over the bars into a lot of rocks.

    Premier Icon xcentric
    Free Member

    18.3 if atmospheric pressure <1018mb, otherwise 19.2

    Premier Icon shinsplints
    Free Member

    thanks xcentric, think we may even be getting a bit of sleet in the Shire tomorrow. Oh god, what to do.

    Premier Icon njee20
    Full Member

    Is there a sheldon brown type calculator for 26″ wheel psi / 29″ wheel psi ?

    It’s like gears – the equivalent pressure is 10% harder on a 29er, more air innit, so 24.6 on 26″ wheels is like 22.1 psi, which is probably too soft frankly.

    Premier Icon shinsplints
    Free Member

    I don’t think I’m going now, I can’t handle all these calculations. What if I fall off or get overtaken by someone on a small wheeled bike.

    Premier Icon chives
    Free Member

    Have you taken in to account the need for seasonally-adjusted values for the friction coefficient of loam – I mean, we all know what the figure is for wet roots, but that leaf litter can be a tricky.

    Premier Icon higthepig
    Free Member

    I had a perfect ride there a while ago, but as my bike came from Germany and the tyre pressures are measured in Bar, I am unable to help.

    Premier Icon patriotpro
    Free Member

    Pump them up til your bicep is hurting then go ride

    Premier Icon thisisnotaspoon
    Full Member

    we all know what the figure is for wet roots

    Little known fact that the coefficient of friction of roots is actualy absolute zero. It’s one of the universal physical constants, like avagadros number, the speed of light in a vaccum, and the sheep:human ratio in Wales.

Viewing 14 posts - 1 through 14 (of 14 total)

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