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  1. #101
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    Quote Originally Posted by NYrr496 View Post
    I had built a bunch of wheels and never had this problem, so I never checked for it.
    Until last year...
    I built up a pair of 35mm Velocity Blunts for my own bike. Mounted up tires (tubeless) and went for a 20 mile ride. In the middle of my ride, my bike started to feel all loose and weird. I checked my tire, figuring it was soft and it was not. Then I noticed all of my spokes were loose on my rear wheel.
    When I got home, I took the tire off and checked the wheel out. tensions were low, but not like with the tire mounted, so I mounted the tire back up and retensioned the spokes with the tire mounted. Wheel has been fine since.
    Then I realized I had just laced a set of Flows for a friend's bike build I was doing, so I mounted his tires and checked tension... Same thing. So I tensioned his with the tires on. He's been on that bike about a year now with no problems.
    This has been with Geax Saguaros on all three of these wheels. I recently built a 26" Flow and mounted up a Specialized rear tire and no change in tension.
    I guess you should always just check.
    I think its probably better to measure things with tube/tire of choice mounted, and then measure again with the combo aired up. I mean what you be more realistic than that. all these rim and tire makers can suck d1ck imo, they have absolutely not goddamn clue whatsoever wtf theyre talking about.

    I'd say max allowable tension measured at your operating tire/tube pressure, obviously with the tires and tubes mounted. but hey wtf do i know?

    I retensioned and retrued my old wheel by pumping them up to 3.0 bar and then do all the tensioning. and now 5 years after that they are still true. gho figure.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.

    Quote Originally Posted by iheartbicycles View Post
    Specialized sucks ass.

  2. #102
    Merendon Junkie
    Reputation: abelfonseca's Avatar
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    I have found an enlightening web page dedicated to the bicycle wheel and wheel building where they touch on this issue. It seems to concur with the theory of rim deformation along the spoke bed.

    "Rim Deformation
    Rims, especially aluminum, are built to be rigid. Loaded with 20 to 32 tensioned spokes, they become an amazingly firm, almost brittle structure. But to look closely, rims elastically deform in dramatic ways.

    When spokes are attached, a huge compressional force is applied to the rim hoop. It can be 600lbs, measured at a rim joint. Due to the small mass and density of the rim, the hoop actually becomes temporarily smaller. Clincher tire pressure pushes rim beads outward. You can use calipers across the brake track to see those surfaces change. With pressure, parallel brake tracks become angled more than one degree.

    Inflation pressure spreads the rim at the brake which affects the rim ďbellyĒ below. For many rims, the change to the belly is enough to increase spoke length and change tension over 20%. Deflate the tire and brake track springs back and spoke tension rises.

    With riding, all these elastic deformations combine to define wheel behavior. Itís not just the tire thatís in constant elastic motion. A structure as light as a standard bicycle wheel is a complex, dynamic structure. No wonder there are so many opinions and observations about the zillion combinations of components, spoke tension, tire pressure, and riding.

    The more I learn about wheels, the more secrets are revealed. I discovered the elastic properties of spokes while studying them at Wheelsmith in the 1980ís. Now itís clear that all wheel components have elastic properties that affect their neighbors and wheel performance. This elasticity is substantial and you should bear its contribution in mind whenever designing, building, or riding these magnificent structures."

    Elasticity - Wheel Fanatyk

    I dont know if the article had been mentioned or cited here before.

    Cheers,
    Abel

  3. #103
    transmitter~receiver
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    Tire Pressure and Spoke Tension

    Quote Originally Posted by abelfonseca View Post
    I have found an enlightening web page dedicated to the bicycle wheel and wheel building where they touch on this issue. It seems to concur with the theory of rim deformation along the spoke bed.
    [...]
    I dont know if the article had been mentioned or cited here before.

    Cheers,
    Abel
    We're lucky to have both Hjertberg brothers' contributions to the cycling community.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

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