• 03-18-2020
    ToiletSiphon
    Max air pressure on hybrid wheel
    So I want to mount my old Giant Escape hybrid to my wheel-on tacx trainer, which recommends the tacx tire to be inflated to 110 psi. Can this be somehow bad for the rim, which was made with 60-70 max psi in mind?

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  • 03-19-2020
    changingleaf
    Does the rim have a tire pressure guideline? I would follow the tire guideline, unless the rim has one. 70psi should be fine for a 30+mm hybrid tire.
  • 03-19-2020
    Lombard
    I have to wonder about the trainer's 110 PSI recommendation. That's probably for a road tire.

    I agree with Changingleaf's recommendation. No reason to inflate a hybrid size tire any higher than 70 PSI unless you are 250+ lbs.
  • 03-19-2020
    Kerry Irons
    Quote:

    Originally Posted by ToiletSiphon View Post
    So I want to mount my old Giant Escape hybrid to my wheel-on tacx trainer, which recommends the tacx tire to be inflated to 110 psi. Can this be somehow bad for the rim, which was made with 60-70 max psi in mind?

    How do you know the rim was designed for a 70 psi max? The forces on the rim are a combination of tire size and tire pressure. All of the force on the tire casing is resolved at the point where the tire contacts the rim, so at the same pressure, a larger tire puts more force on the rim. A 40% increase in tire size doubles the force on the rim.

    And as noted by Lombard, the 110 psi number is probably for a 23-25mm road tire. The pressure recommendation is about tire slippage and required pedaling force, so just experiment with tire pressure to see what works.
  • 03-19-2020
    Jay Strongbow
    I'd be willing to take the risk of crashing on the trainer if I really cared to find out.

    But I don't nor have I found any reason to care about tire pressure on that style trainer.
    If you're into statistics you'd want to keep PSI and pressure the same, but otherwise it doesn't matter.
  • 03-19-2020
    Lombard
    Quote:

    Originally Posted by Kerry Irons View Post
    And as noted by Lombard, the 110 psi number is probably for a 23-25mm road tire. The pressure recommendation is about tire slippage and required pedaling force, so just experiment with tire pressure to see what works.

    And as noted here, keep in mind the word "recommendation". That is different from phrases inside triangles with exclamation points.
  • 03-19-2020
    No Time Toulouse
    I'd try pumping it up to 150 psi, and see what happens......
  • 03-19-2020
    Lombard
    Quote:

    Originally Posted by No Time Toulouse View Post
    I'd try pumping it up to 150 psi, and see what happens......

    Wear ear protection.
  • 03-20-2020
    ToiletSiphon
    It is for the 23mm Tacx tire,not for the hybrid tire (which was a 32mm rated for 60psi max,that I replaced with 28mm slicks for a muuuuch faster commute!). I try to keep it consistently at the same pressure so that the trainer stats stay meaningful.

    I guess the 23mm will fit okay on the 18mm inner width rim?

    I'm not afraid of crashing the trainer, I just don't want to weaken the rim and have it fail on me when I eventually take the bike outside with its usual tires at its usual pressure.

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  • 03-20-2020
    cxwrench
    Quote:

    Originally Posted by ToiletSiphon View Post
    It is for the 23mm Tacx tire,not for the hybrid tire (which was a 32mm rated for 60psi max,that I replaced with 28mm slicks for a muuuuch faster commute!). I try to keep it consistently at the same pressure so that the trainer stats stay meaningful.

    I guess the 23mm will fit okay on the 18mm inner width rim?

    I'm not afraid of crashing the trainer, I just don't want to weaken the rim and have it fail on me when I eventually take the bike outside with its usual tires at its usual pressure.

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    Just wondering what pressure you inflated the 28mm tires to?
  • 03-21-2020
    ToiletSiphon
    Quote:

    Originally Posted by cxwrench View Post
    Just wondering what pressure you inflated the 28mm tires to?

    Probably too much. About 75 front, 85 back. I'm 145 lbs. Comfort is more than okay.

    I don't like the feeling when going lower, the bike feels mushy when standing up.

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  • 03-23-2020
    Kerry Irons
    Quote:

    Originally Posted by ToiletSiphon View Post
    Probably too much. About 75 front, 85 back. I'm 145 lbs. Comfort is more than okay.

    I don't like the feeling when going lower, the bike feels mushy when standing up.

    Probably significantly more pressure than needed at your weight, but it's up to you. Lots of people want to get more "road feel" and so pump their tires too hard.