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  1. #1
    torontonian and proud. GSmith's Avatar
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    First wheel trueing, defying physics and logic

    Hey,

    So I picked up a 2003 Peugeot Success today for a city commuter. Absolutely love it.

    The only comment the seller had was that the back wheel would definitely need trueing, which it absolutely does. Now I've never trued a wheel before and I don't have a trueing stand, but since I don't need this to be accurate to the millimeter, I'd like to try it myself.

    I've started - I did start with the tire on, but I've since deflated & removed it and put the rim back on the frame. The wheel is worse than when I started - probably a solid 6-7mm of warp going on right now.

    But the situation has me lost. I understand the physics of trueing - the right side spokes (looking from the bottom, bike upside down) pull the tim towards that side when tightened, and if you loosen them a little and tighten the other side, the reverse happens. Makes sense. The problem isn't that I'm just plain turning things the wrong way. Right now the wheel is way off to the right in one area, probably 5 spokes long, but the left side spokes are tight as can be and the right very loose (wouldn't ride on it this way). So I'm lost. I can't tighten the left spokes any further, I already stripped the nipple on one (on the inside edge of the rim, I switched to using a flat head on the inside heads afterwards).

    So is the rim just shot? Is there something I'm missing? Any tips would be greatly appreciated, I want to be able to ride this thing some more tomorrow!

    Thanks in advance!
    >2500k and not a single flat. I don't think it's fair to knock on wood anymore. (update feb 7 2011: whoops)
    2009 Cannondale CAAD5 (white), stock Shimano 105 pretty much everything. Slowly Ultegra-izing, so far: the chain.
    early 90's Peugeot Success, the city commuter (wanna help finding a date on this one?)

  2. #2
    DRF aka Thrifty Bill wrk101's Avatar
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    When you run out of spoke to do any further tightening, you need to loosen the adjacent spokes instead. But since you mention those are loose already, sounds like your rim is bent. I would head to a shop next.

    When you run out of thread on the spoke, its time to stop tightening.

  3. #3
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    Anytime spokes are radically different in tension effective truing is not possible. Loose spokes and a true rim are a recipe for failure.

    Truing depends on an unstressed rim, which you do not have. The wheel was in an accident which physically bent the rim toward one side. The side it's bent toward would have loose spoke, the other side tight ones. Impossible to fix without physically bending the rim back, and unlikely to be fixed event then. This is particularly true if it's not a symetrical bend (U shaped) but more S shaped. The wheel is most likely totaled. Even if a skilled person could make it rideable it will either have poor strength or poor trueness.

    The inflated tire was probably helping at least a small amount to hold the wheel a bit straighter, thus the wheel being worse now.

  4. #4
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by wrk101 View Post
    When you run out of spoke to do any further tightening, you need to loosen the adjacent spokes instead. But since you mention those are loose already, sounds like your rim is bent.
    Bent is bad. You might be able to pull the rim straight by fooling with the spokes but you will never make a good wheel with a bent rim. If it was my bike, I'd replace it.

  5. #5
    torontonian and proud. GSmith's Avatar
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    Thank you, guys, it does sound like the rim's totalled.

    I did post a little video of the situation: http://www.flickr.com/photos/gavinsmith/4604976424/

    The seller is replacing it for me tomorrow though, a friend of mine. Has a spare.
    >2500k and not a single flat. I don't think it's fair to knock on wood anymore. (update feb 7 2011: whoops)
    2009 Cannondale CAAD5 (white), stock Shimano 105 pretty much everything. Slowly Ultegra-izing, so far: the chain.
    early 90's Peugeot Success, the city commuter (wanna help finding a date on this one?)

  6. #6
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    Quote Originally Posted by GSmith View Post
    Thank you, guys, it does sound like the rim's totalled.

    I did post a little video of the situation: http://www.flickr.com/photos/gavinsmith/4604976424/

    The seller is replacing it for me tomorrow though, a friend of mine. Has a spare.
    If its getting replaced, I'm not sure I would worry now, but here are my two cents worth anyway. Looking at your video, I have trued worse warps on-the-bike before. Since i didn't see it specifically mentioned (though I miss stuff all the time), and since you said the wheel is worse than when you started, you do know that when you are looking down a spoke tword the hub you turn counter-clockwise to tighten, right? Its not like a screw that you turn clockwise to tighten. You probably already knew this, just want to make sure something so simple and small wasn't overlooked!

  7. #7
    torontonian and proud. GSmith's Avatar
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    Quote Originally Posted by bluedragon0 View Post
    If its getting replaced, I'm not sure I would worry now, but here are my two cents worth anyway. Looking at your video, I have trued worse warps on-the-bike before. Since i didn't see it specifically mentioned (though I miss stuff all the time), and since you said the wheel is worse than when you started, you do know that when you are looking down a spoke tword the hub you turn counter-clockwise to tighten, right? Its not like a screw that you turn clockwise to tighten. You probably already knew this, just want to make sure something so simple and small wasn't overlooked!
    Appreciated! I definitely ensured I was doing that right, though. I actually adjusted using the flat head ends of the nipples that are on the outside edge of the rim, below the inner tube, because I managed to 'strip' one of the nipples using the tool (I think the one I have is ever so slightly too big, or the spokes are just way too tight).

    In the video, I show two arrows on the rim - that's there the warp starts and stops, it's approximately 1/5 of the rim. To me that suggests it is in fact damaged.. it's a 7-10mm warp over the span of about 15cm. If you've fixed worse, though, anything in particular you did?
    >2500k and not a single flat. I don't think it's fair to knock on wood anymore. (update feb 7 2011: whoops)
    2009 Cannondale CAAD5 (white), stock Shimano 105 pretty much everything. Slowly Ultegra-izing, so far: the chain.
    early 90's Peugeot Success, the city commuter (wanna help finding a date on this one?)

  8. #8
    Senior Member peripatetic's Avatar
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    Quote Originally Posted by GSmith View Post
    But the situation has me lost. I understand the physics of trueing - the right side spokes (looking from the bottom, bike upside down) pull the tim towards that side when tightened, and if you loosen them a little and tighten the other side, the reverse happens. Makes sense. The problem isn't that I'm just plain turning things the wrong way. Right now the wheel is way off to the right in one area, probably 5 spokes long, but the left side spokes are tight as can be and the right very loose (wouldn't ride on it this way). So I'm lost. I can't tighten the left spokes any further, I already stripped the nipple on one (on the inside edge of the rim, I switched to using a flat head on the inside heads afterwards).
    Wheel truing can be easier than it seems to a complete neophyte, but while the basic principles are fairly easy to follow, there are a number of complications it's important to keep in mind in order to get your desired result. Failure to do so can actually lead to a lot of head-scratching and confusion.

    I'll refer you to the late SB for a thorough read, but also for anyone else, I'll highlight the situation you seem to be describing:

    CHECK THE RIMS
    In most out-of-true wheels, the problem is the result of the rim being bent. Remove the tire, tube and rim tape if you haven't already...

    Spin the wheel and look to see where the worst bend is-the place where the rim is farthest from its average position. Which side is it bent toward? Let's assume that it is bent to the right in one area, and that this is the most severe bend on the rim. Move the right-hand brake shoe (i.e. a 'feeler') in toward the spinning rim until it just rubs at one point in the wheel's rotation., Feel the tension on the spokes in the immediate area of the bend.

    If the spokes that go to the right flange of the hub are loose and the ones that go to the left are tight, that is the result of the rim being deformed. Since the rim has been pushed over to the right, it eases the tension on the right spokes while increasing the tension on the left spokes. If you just tighten the left spokes in the area of the bend, it will pull the rim back toward the middle, but it also will create a flat spot. Even if you are able to get the wheel true this way it will be seriously weakened because the spoke tension will be uneven.

    The proper repair in this situation is first to bend the rim back to its normal shape, and then fine true it with the spokes.
    Lightweight wheels can be bent fairly easily by placing your knee or foot right on the peak of the bend, and pulling with your hands on either side of the bend. This or a similar technique should be used whenever a rim is bent more than 1 centimeter to the side and there are no broken spokes. Even wheels that have collapsed into the shape of a potato chip usually can be made rideable again with this technique This is a very useful on-the-road repair-it even can be done without removing the wheel from the bike. If you are not sure of your skill, you are less likely to do further damage bending wheels over your knee, spectacular as it may look, than with a spoke wrench used carelessly.

    If the rim is bent to the right, and the right side spokes are tighter than the left side in the area of the bend, or if the tensions are about equal, the spokes are the cause (and cure) of the trouble. Working only in the immediate area of the bend, tighten the left spokes and loosen the right spokes, keeping the overall tension the same. For instance, if the bend involves four spokes, you might tighten each of the left spokes one-fourth turn and loosen each of the right spokes one-forth turn. If only three spokes are involved, say two on the left and one on the right, you might tighten each of the left ones one-eighth turn and loosen the one on the right one-fourth turn. By maintaining this balance you can true the wheel from side to side without making it go out of round. Until you have acquired a lot of experience truing wheels, don't turn any spoke more than one-fourth turn at a time for side-to-side truing.


    * * *
    Others here already mentioned the problem might be that the rim's actually deformed, but I thought Sheldon's description would help make sense of why.

    A lot of people who learn how to true wheels on their own think it's all just a matter of tightening and loosening spokes, but before doing that, it's crucial to check whether the spokes have even tension and the rim itself is bent. The situation you describe in the beginning--rim to the right AND right side spokes are loose--indicates the rim is bent. As Sheldon points out, the spokes are loose because the rim has been bent towards them, relieving the original tension on them. If you go and try and tighten those right side spokes before fixing the rim, you'll actually make things even wonkier.

    The reason why Sheldon's description of truing is very good is b/c he includes explanations of looking for blips, evening tension on all spokes AND bending the rim back into shape before attempting to even out right side and left side tension. The order in which you attempt these things is very important, especially with, as in your case, you have a wheel whose provenance you don't know. If you knew it were your own wheel and it just had a bit of a wobble from riding on underinflated tires over some potholes, then you could safely take the right side/left side spoke adjustments first. But in this case, it's important to figure out if the tension is even first, then check for actual physical deformations to the rim. You might consider loosening all the spokes on this wheel completely and seeing at that point how bent up the rim looks. I'm guessing it may've been hit by a car while parked or something like that.

    Finally, one thing they don't cover in online descriptions of wheel truing (I haven't read it on Sheldon's site, either) that you should be aware of--when you tighten a given spoke, that puts tension on the spoke opposite that one on the same side of the flange--it's pulling the hub away from that other spoke. So realize you're actually increasing tension in both directions when you do that. Thus, if you go around just blindly tightening spokes without checking relative tension, you could end up near the end with a bunch of over-tensioned spokes. For this, I highly recommend learning to tell tension by listening to the relatives pitches of adjacent spokes. This actually works quite well at getting things pretty even.

    Good luck, and be patient!

  9. #9
    Mechanic/Tourist
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    "Don't try this at home."

    As I mentioned earlier anyone attempting to fix a bent rim has to physically bend it back - by loosening spokes in the area and then pressing down carefully on a flat surface or sometimes twisting it back between two parallel surfaces. In most cases you should attempt to do so only in an on-road situation where you just want to get the bike rideable or if you are an experienced mechanic trying to help a person who cannot afford a new wheel. To straighten a rim "AGAP" and then retension, round and dish, also best possible you should expect to pay $30-40.

    You are better off first learning to do the host of easy adjustments that will save you having to take the bike in for tune-ups than to try to learn the one-off skill of saving a wheel.

  10. #10
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    Quote Originally Posted by cny-bikeman View Post
    .. The wheel was in an accident which physically bent the rim toward one side. ..Impossible to fix without physically bending the rim back, and unlikely to be fixed event then. This is particularly true if it's not a symetrical bend (U shaped) but more S shaped. The wheel is most likely totaled. Even if a skilled person could make it rideable it will either have poor strength or poor trueness.
    I don't quite agree with all that. "My" fleet of beater bikes have several wheels with rims that have been bent back and then trued and tensioned.
    As I haven't been able to ride them to destruction I can't vouch for "exactly" how much strength they've lost, but in that setting they're indistinguishable from the untouched rims.

    Mind, from a rationality standpoint I still hold this to be a bad idea. I've never been able to get enough of a return bend w/o unlacing the wheel, at which point it'd be just as fast to lace the wheel up to a new rim, avoiding the bending and any nagging doubts about long-term performance.

    But if you have the time to spare it's a quite satisfying repair to pull off.

    Oh, and it "has" to be rim with a welded seam. Pinned seams don't stand up well to the abuse needed to get the rim back into plane. One would have to be very lucky with the location of the bend if one would be able to rescue a pinned and bent rim back into service.

  11. #11
    velo-orange
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    Well, looks lime you can have a bit of fun, learning how (and NOT how) to true a rim/ build a wheel.

    all you need is a spoke wrench and a bit of time.

  12. #12
    Senior Member DannoXYZ's Avatar
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    In order for the OP to get the wheel trued, I suspect he really needs to exert the opposite bending force to the rim so that it's at least flat; spoke-tension can only make up for so much. While it's possible to loosen spokes and bend the rim, I find it easiest to just unlace the wheel completely and use a glass coffee table as a guide to flatness. Find the high/low spots and mark them. Then place the rim on the edge of a door-frame and PUSH!!! Don't over-bend it, but do it incrementally until the rim lays perfectly flat on the glass. Re-lace rim onto wheel and you'll find truing will be A LOT easier.

    Now the strength of the wheel will still be weaker than a brand-new rim, but definitely much stronger than it is now. I'm still riding on some of these re-bent wheels 10-years after fixing it this way. Then again, Mavic MA-40s are legendary for their toughness; probably more durable than anything they've produced since.

    Oh, and get an electric screwdriver and file a slotted screwdriver bit into the shape of a nipple-driver. You can unlace a wheel in less than 3-minutes and build it back up in 5-10.

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