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Thread: Tyre pressure for custom bikes

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    Member 98kellrs's Avatar
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    Tyre pressure for custom bikes

    So, I have a pretty custom cafe racer from the 70's which I've modified with modern paralever suspension, a gsxr front end (slightly more unsprung weight at the front) and slightly wider and better performing tyres.

    I typically ride a few times a week, and that's mostly hills runs.

    The question is, how do I work out what my optimal tyre pressure is? Is there a method for calculating it, or is it just done off what the tyre manufacturer recommends? I've been running around the mid-low 30's cold front and rear, which seems OK.
    Ryan

    Quote Originally Posted by Aufitt View Post
    Try Para045, he definitely sounds all gooey in the fork for ya

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    Member valvolux's Avatar
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    I would use your mothers age divided by the square root of the diameter of your scrotum
    Nah. tyre manufacturers recommendation......
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    Member 98kellrs's Avatar
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    Quote Originally Posted by valvolux View Post
    I would use your mothers age divided by the square root of the diameter of your scrotum
    Nah. tyre manufacturers recommendation......
    Ironically, that comes out at almost exactly what I'm using...
    Ryan

    Quote Originally Posted by Aufitt View Post
    Try Para045, he definitely sounds all gooey in the fork for ya
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    Member vegie's Avatar
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    Quote Originally Posted by 98kellrs View Post
    Ironically, that comes out at almost exactly what I'm using...

    Ok, who got out the tape measure and did some calcs??

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    Member agrid's Avatar
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    I used to run expensive sports bike tires on my KTM supermoto, I ran much less than recommended pressure because the bike was much lighter than a sports bike.
    -

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    Member SomeBloke's Avatar
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    Contact the tyre OEM if you are serious about it, let them know the static tyre loads and they can give a decent pressure. Realistically though, you probably wont be talking to the engineering department and they will tell you to stick to the range 'on their website'.

    Try a normal pressure between say 25 and 40 and keep changing it up until it feels good (ie not very elastic response to a steering input) lower pressure is usually better for grip, higher pressures for profile, so it is a bit of back and forth. I doubt you will run in to heating issues on the road (or at least shouldn't).
    "Life begins at the end of your comfort zone."


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    Member filbert's Avatar
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    As a rule of thumb for a track ridden bike you can use hot pressure variation to work out optimum temperature rise...

    Cold pressure ridden until hot then should be +10% front and +20% rear.

    You can apply this by checking your cold pressure then going for a ride on your preferred route then stop and check the pressures, if your 30 turns into 33 you're in a pretty safe operating range.
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    Member 98kellrs's Avatar
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    Quote Originally Posted by filbert View Post
    As a rule of thumb for a track ridden bike you can use hot pressure variation to work out optimum temperature rise...

    Cold pressure ridden until hot then should be +10% front and +20% rear.

    You can apply this by checking your cold pressure then going for a ride on your preferred route then stop and check the pressures, if your 30 turns into 33 you're in a pretty safe operating range.
    Thanks Filbert, I'll do some reading up about that as it's along the lines of what I was thinking.

    The horse was in the same field as the pond, it just needed nudging in the right direction for a drink
    Ryan

    Quote Originally Posted by Aufitt View Post
    Try Para045, he definitely sounds all gooey in the fork for ya

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