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Thread: What is True?

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    "3' A'HOLE" Schrup's Avatar
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    What is True?

    What do you guys consider true? I bought a truing stand last Friday & straightened 4 wheels out that were slightly ovaled & wobbly. The stand has already paid for itself. I'm wondering what you guys consider acceptable tolerances. I try to get them inside of 1mm. I had to laterally true the set with Bontrager hardcase tires after I remounted them because they were so difficult to get on. I'm wondering if I need to buy a tension meter, I would like to take a stab at building my own wheelset this fall. I bought a new wheelset & crashed a week later, that's when I figured that I needed to learn to do my own truing. Is anyone able to get them perfectly straight once they've been knocked out of true?

    I haven't seen anything in the DIY wheel truing instructions that indicate what is acceptable as far as tolerances. I wish I would have checked out how true my new wheelset was before I crashed them. How critical is dishing when truing? I noticed that I had to adjust my Vbrakes over a few MM when switching between wheelsets, is this something I should be concerned about? I put a small hole in the rim tape at one of the spoke holes when I was trying to get one of the hardcase tires off & didn't replace it before remounting the tire. Is this no biggie or should I go through the PITA of replacing it ASAP? Thanks for any advise.

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    * vpiuva's Avatar
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    New wheels often claim tolerances of 0.2mm lateral and out-of-round, but that's probably laughable. 1mm is as good as most of us probably need. I've seen shops use 0.5mm as their standard, but I have no idea if this is universal.

    Once crashed, the tension is not going to be as equal as on a new rim, so go with trueness.

    All the wheels should be dished alike so no brake adjustments.

    Do you want to fix your flat & rim tape while on a ride? Or while it's in your basement

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    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by Schrup View Post
    What do you guys consider true?
    To me, it's true if:
    (a) I can adjust the brakes as tight as I want them, and it never rubs, and
    (b) It doesn't get worse over time

    In practice, I usually try to true my wheels to within 1mm.
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    I think .5 mm is pretty good, lateral true, radial true, and dish. Brake pads and calipers are worthless when it comes to wheel dish. Brake calipers are not necessarily centered on the frame.
    If you want to check dish flip the wheel over in the stand and see if the rim stays the same distance from the truing caliper or indicator.

    Al

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    My bike's better than me! neil0502's Avatar
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    Quote Originally Posted by moxfyre View Post
    To me, it's true if:
    (a) I can adjust the brakes as tight as I want them, and it never rubs, and
    Without putting a number on it, this sounds as good, to me, as anything else....

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    rebmeM roineS JanMM's Avatar
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    Gosh. I thought this thread was gonna be about ethics or philosophy.

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    rebmeM roineS JanMM's Avatar
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    Gosh. I thought this thread was gonna be about ethics or philosophy. "An Essay on the Nature of Truth; What is True?"

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    Quote Originally Posted by JanMM View Post
    Gosh. I thought this thread was gonna be about ethics or philosophy. "An Essay on the Nature of Truth; What is True?"

    Well, it is.

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    Non Tribuo Anus Rodentum and off to the next adventure (RIP) Stacey's Avatar
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    Is truth unchanging law?

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    Quote Originally Posted by Stacey View Post
    Is truth unchanging law?
    I sure hope not, would hate to get the lawyers involved.

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    Quote Originally Posted by vpiuva View Post

    Once crashed, the tension is not going to be as equal as on a new rim, so go with trueness.
    Actually the goal is to carefully bend back the rim when possible, get the best possible tension and then accept slighly out of true as a trade-off for better stability. If you only focus on true then it won't stay straight very long. What good is 1 mm more true if it comes out of whack the first time you hit a pothole or swerver hard?

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    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by cny-bikeman View Post
    Actually the goal is to carefully bend back the rim when possible, get the best possible tension and then accept slighly out of true as a trade-off for better stability. If you only focus on true then it won't stay straight very long. What good is 1 mm more true if it comes out of whack the first time you hit a pothole or swerver hard?
    +1

    If a rim is bent, you can't have BOTH even tension and a perfectly true rim. You'll have to compromise. To prolong the wheel, I try to make the tension as even as possible without making the wobble excessive.
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    "3' A'HOLE" Schrup's Avatar
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    Quote Originally Posted by vpiuva View Post
    Do you want to fix your flat & rim tape while on a ride? Or while it's in your basement
    I guess I'll pull my tire off the rim after I get my new aluminum tire levers that I ordered from the LBS. The plastic levers didn't work on the hardcase tires. Is being 3mm off center cause for concern?

    I've found that like anything else, the truth is best used in moderation, for example, "Honey, does this make me look fat?"

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    Grumbly Goat Bushman's Avatar
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    ^ oooooh thats the worst question you can answer...never go there...it'll bite you hard...
    You ride a bike, we GET IT, no need to rant about it or look down on others....its JUST A BIKE...get over yourselves.

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    Quote Originally Posted by Schrup View Post
    I guess I'll pull my tire off the rim after I get my new aluminum tire levers that I ordered from the LBS. The plastic levers didn't work on the hardcase tires. Is being 3mm off center cause for concern?

    I've found that like anything else, the truth is best used in moderation, for example, "Honey, does this make me look fat?"

    The truth is if honey asks you if being 3 mm off-center makes her look fat your answer is much cause for concern.

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    Pwnerer Wordbiker's Avatar
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    The measure of "true" for a bicycle wheel is the limitation of your eyesight or your patience, whichever comes first. This may be modified by the level of impatience of the customer, often making the measure of true, "good enough for who it's for".
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

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    cab horn
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    1mm is definitley not good enough for shop. A true wheel will have zero visible wobble to it. Radial or lateral.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

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    Pwnerer Wordbiker's Avatar
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    Quote Originally Posted by operator View Post
    1mm is definitley not good enough for shop. A true wheel will have zero visible wobble to it. Radial or lateral.
    You mean, barring that it's a:

    *Rim which may not meet that tolerance even when new and unbuilt, such as a steel rim with a pronounced seam.

    *BMX or Downhill rim that has worse discrepancies in the tires alone, flat spots, gouges, etc. and the owner just wants it to turn in the frame.

    *Heavily used, defective or damaged rim that the owner refuses to replace, hence my "good enough" comment.

    *Bike with a disc, drum, roller or coaster brake.

    *Toy/Department store bike.

    It is an imperfect world we live in. Sure, a quality rim for rim or disc brake application that is not damaged not only should be completely round within .5mm tolerance, but should be capable of true to that tolerance or less when built up. At a guess I'd say that constitutes 25% or less of all wheels brought to a shop for truing.
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

  19. #19
    cab horn
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    Quote Originally Posted by Wordbiker View Post
    You mean, barring that it's a:

    *Rim which may not meet that tolerance even when new and unbuilt, such as a steel rim with a pronounced seam.

    *BMX or Downhill rim that has worse discrepancies in the tires alone, flat spots, gouges, etc. and the owner just wants it to turn in the frame.

    *Heavily used, defective or damaged rim that the owner refuses to replace, hence my "good enough" comment.

    *Bike with a disc, drum, roller or coaster brake.

    *Toy/Department store bike.

    It is an imperfect world we live in. Sure, a quality rim for rim or disc brake application that is not damaged not only should be completely round within .5mm tolerance, but should be capable of true to that tolerance or less when built up. At a guess I'd say that constitutes 25% or less of all wheels brought to a shop for truing.
    Sorry, my disclaimer was we are working with new wheels only.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

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    I have a Bontrager Racelite manual that says 0.4 mm laterally and radially is the standard. I need dial indicator to get that close, and sometimes an old rim will never get that true. The Park website says 1/16 inch laterally and 1/32 inch radially. The Park numbers are about the best I can do without a dial indicator, and better than I can do using the brake pads as an indicator. Once you get down to those numbers, it's better to concentrate on more equal tension.

    em

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    Quote Originally Posted by operator View Post
    Sorry, my disclaimer was we are working with new wheels only.
    My wife's Bontrager Race Lite wheels were out more than .5 mm when brand new in the box. The front was out about 1 mm.

  22. #22
    Small Member maddmaxx's Avatar
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    Quote Originally Posted by JanMM View Post
    Gosh. I thought this thread was gonna be about ethics or philosophy. "An Essay on the Nature of Truth; What is True?"
    That which is true is not false. But in bicycling (as proved by the tour) false is hard to define, it wobbles a bit. So it follows that those things that are true do not wobble.

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