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  1. #1
    ............ deerhoof's Avatar
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    tire feels unbalanced

    I installed a pair of crossraods on my bike yesterday. When I spin the the rear wheel and hold the bike by the back of the saddle I feel a kind of up and down motion coming from the tire. Not sure if this will go away as the tire gets broken in or not. Did I mess something up when i changed tires?

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    Senior Member DannoXYZ's Avatar
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    Do you feel it or see it? Tyres are usually fairly uniform and any wobbling is due to misalignments during install and getting the bead seated evenly all the way around. If you feel it, then it's an imbalance due to the extra metal at the pinned seam on the rim which isn't always offset by the weight of the valve-stem on the opposite side. Or if you've squeezed Slime into the tube, there's a lump of it in one spot that needs some speed and riding to smear itself around the insides more evenly... There's actually a product called BalancePlus for motorcycles that somehow balances a wheel with use, not sure how it works though...

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    ............ deerhoof's Avatar
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    i think i just didn't seat it right. It definately feels out of balance though.

  4. #4
    Curmudgeon Wil Davis's Avatar
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    Quote Originally Posted by deerhoof
    I installed a pair of crossraods on my bike yesterday. When I spin the the rear wheel and hold the bike by the back of the saddle I feel a kind of up and down motion coming from the tire. Not sure if this will go away as the tire gets broken in or not. Did I mess something up when i changed tires?
    I notice the same effect with wheels especially the ones with the deep-vee cross-section rims fitted with tubes with long-stem (60mm) valves, even when the tyres and tubes are seated correctly. I try to balance it somewhat by fitting the sensor magnet for the computer at 180 to the position of the valve.

    - Wil
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    sch
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    I have never built a wheel or mounted a tire on a wheel that did NOT do that. Bike wheels are not balanced and mirabile, it makes no difference!
    Steve

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    Quote Originally Posted by deerhoof
    i think i just didn't seat it right. It definately feels out of balance though.

    Take it off and put it back on again. Sometimes very occasionally the tyre does not go on correctly and then is not round. Happened me the other night on my road bike.

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    Quote Originally Posted by deerhoof
    I installed a pair of crossraods on my bike yesterday. When I spin the the rear wheel and hold the bike by the back of the saddle I feel a kind of up and down motion coming from the tire. Not sure if this will go away as the tire gets broken in or not. Did I mess something up when i changed tires?
    Spin the wheel and look at the line at the edge of the tire near the rim. If this is not parallel with the rim all the way round and on both sides, or if the tire is obviously going up and down, deflate the tire to about 20 psi, remove it from the bike and bounce it gently on the ground all the way round. Make sure the valve is properly seated by pushing it in so that the tire seats into the rim at that point. Spin the wheel again and observe as before. If OK, inflate to recommended pressure. Do not over-inflate or you may cause the tire to be pushed off the wheel and end up with a worse bounce!!

  8. #8
    use your best eye kenhill3's Avatar
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    Probably not as possible with road tyres, but I have come across some MTB tyres that were grossly out of balance because of the molding/manufacturing. The rubber was somehow misshapen and no amount of reseating or manhandling would cure the problem. Defective product!

  9. #9
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    Quote Originally Posted by sch
    I have never built a wheel or mounted a tire on a wheel that did NOT do that. Bike wheels are not balanced and mirabile, it makes no difference!
    Steve
    All you need to do if you have that problem is to move the tire on the rim 45 degrees (of course you could lose that "pro" look of the tire label being in line with the Presta valve); retest the tire if it still wobbles move 45 degrees again etc until the wobble is reduced. Most of the time I can get any wobble to be all but eliminated. Also as another poster mentioned the position of the computer magnet will have a major effect and should be opposite the valve. Cheap tires and tubes will also cause a problem with wobble due to imperfect manufacturing; I've actually seen tires with bulges where the rubber was thicker then in other areas! but that doesn't effect a kids bike that will never go above 15mph.

    Does in inbalance tire have an effect on your riding...depends on how fast your going to go. The kind of balance is called harmonic, and this harmonic vibration is similar to a car tire which is why a car tire will only vibrate between a narrow range of speed like 45 to 55, but I've seen car tires start ot vibrate as low as 35 but will only last in about a 10mph window. So on a bike unless the wobble is very severe (like the one I had when I absentmindly once placed the computer mag near the valve) your not going to feel much if anything until you exceed about 30mph. When I did the computer mag gaff I thought something was wrong with my bike it vibrated so badly, but this didn't get noticed until about 25 to 30mph.

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    Quote Originally Posted by froze
    Also as another poster mentioned the position of the computer magnet will have a major effect and should be opposite the valve.
    That's not what dannoXYZ said. Actually the rim seam is usually the heavey side of the wheel and the seam is opposite the valve. Except for very long valves like the 60mm valves that Wil Davis mentioned the weight of the valve may not enough to offset the weight of the seam.

    From my experience I'd say that rim seams, valves, and magnets do not have a big effect on wheel balance.
    I think radial wobble is more often caused by tires not properly seated, wheels out of true radially, and defective tires.

    Al

  11. #11
    Senior Member kf5nd's Avatar
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    get rid of the wheel reflector! it's useless anyhow...

  12. #12
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    When I built up the Cross-Check last year I had an annoying out of balance feel to both front and back wheels. Turns out the doubling up of the rim tape as it completed its circuit and overlapped itself was enough to cause the tire to sit slightly different in that spot.
    This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.

  13. #13
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    Most of todays modern rims are machined thus the weight of the seam is eliminated; therefore if you have a magnet attached to a spoke very near to the rim-not near the hub since the close the mag gets to the hub the less likely of any imbalance, then a mag can cause a problem, I've experience and others I've know personally as well on people forums such as this one. In fact todays rims are so well made in the balance area that if you let a rim roll freely (by holding the bike off the ground) the wheels will naturally settle with the valve stem ending up on the bottom AND NOT the seam; don't believe me? try it.

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    Quote Originally Posted by froze
    the balance area that if you let a rim roll freely (by holding the bike off the ground) the wheels will naturally settle with the valve stem ending up on the bottom AND NOT the seam; don't believe me? try it.
    Done that many times, all of mine (MAVIC Open Pros and DT RR 1.1) are heaviest at the seam except the Cosmic Carbones with 60mm stems are heaviest at the stem.

  15. #15
    Senior Member DannoXYZ's Avatar
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    Quote Originally Posted by froze
    Most of todays modern rims are machined thus the weight of the seam is eliminated; therefore if you have a magnet attached to a spoke very near to the rim-not near the hub since the close the mag gets to the hub the less likely of any imbalance, then a mag can cause a problem, I've experience and others I've know personally as well on people forums such as this one. In fact todays rims are so well made in the balance area that if you let a rim roll freely (by holding the bike off the ground) the wheels will naturally settle with the valve stem ending up on the bottom AND NOT the seam; don't believe me? try it.
    Yeah, it depends upon the rim. Most rims have an extra piece of metal that's about 3" long that's pinned to each end of the rim on the inside.

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    Quote Originally Posted by DannoXYZ
    Yeah, it depends upon the rim. Most rims have an extra piece of metal that's about 3" long that's pinned to each end of the rim on the inside.
    Most rims today are welded together not pinned, thats why they can be machined so you cannot see a seam. My Torelli Master Series rims are pinned they have a visible seam, but not too many manufactures are pinning them anymore because it takes longer to make.

  17. #17
    put our Heads Together cerewa's Avatar
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    i think i just didn't seat it right. It definately feels out of balance though.
    For many tires, the hardest place to get them properly seated is at the valve stem, because of the extra rubber in the tube near the valve stem. Check that part of the tire first.
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