Missing Rear Spoke

Discussion in 'Fixed & Singlespeed' started by Ruby, Jul 31, 2009.

  1. Ruby

    Ruby Guest

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    My bike is missing a rear spoke, but I have been told (by a mechanic) that this is less important to fix on fixies than regular bikes, and its not totally necessary to replace. Does anyone know why this is please?
     
  2. Grape Ape

    Grape Ape Younger than Hack Tavern Member

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    Sounds to me like they are being lazy. One spoke being broken as long as it isn't causing your wheel to be to far out of true won't get you hurt. But I would be concerned about the end getting in and flattening my tire or causing other damage. It won't hurt you but it would take them a bit of effort so they figure just wait until other work needs done and get the spoke then.
     

  3. hophead

    hophead New Member Tavern Member

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    That's complete BS! Every spoke needs to be there, especially on a rear wheel. I would not let that guy touch your bike.

    Yeah, you might be able to ride it for many miles without a problem. On the other hand, your wheel could also completely self distruct. Most likely the spoke didn't just fall out. It probably broke and broke for a reason. Have a competant bike wrench check it out so you don't end up with a face full of asphalt.
     
  4. tajcrews

    tajcrews New Member

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    Get it replaced when you can. It wont be the end of the world but it will hurt eventually. If you really didn't need that spoke why would it be there in the first place :D
     
  5. Sean

    Sean New Member

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    What kind of wheels are they, and are you a heavy rider?
     
  6. BigDumbBear

    BigDumbBear New Member

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    Every spoke plays a crucial role in counter-balancing another and strengthening the wheel. At the same time, you can break 1 or 2 out and be okay for a while. I've seen guys running wheels on bmx bikes missing roughly 1/3rd of thier spokes and still doing 20 foot gaps and 10 foot drops. It is not recommended though. You should get it replaced and true up the wheel for the best ride and safest function.
     
  7. Retmuter

    Retmuter Member

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    I think maybe this 'mechanic' was referring to it being less important with a fixie due to there being way less dish in the rear wheel. Don't need to make room for a buncha gears so your can get closer to having the long sides of the triangle closer to the same length. While this does indeed make a stronger wheel, I'd still fix it or have someone competent address this concern.
     
  8. SprocketGirl

    SprocketGirl spin... spin.. spin

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    Absolute utter nonsense. Not any individuals thoughts but the concept that a spoke being missing is not an issue. A spokes primary job is unchanged by gear count. Dish plays into a wheels overall strength but not an individual spokes task. I will explain and if anyone wants the maths for the actual physics I can post that as well... First the basics.

    A spoked wheel is amazing. It transfers at times crazy large forces created by rider, the bicycle itself, and terrain into thin rods, EACH being SYSTEMATICALLY compressed as the wheel spins and the load transfers from one spoke to another and so on and forth spinning and going... A beautiful way to balance weight, cost and efficiency.

    Once a wheel is built, centred, trued and tensioned, spokes under tension, basically brace the rim with the hub being used as a central anchor. When built proper and with equal tension EACH and EVERY spoke will distribute the load (work) evenly, while at the same moment keeping the rim circular. Spokes as a team support the wheel, preventing lateral flex and deformaties to the rim. All the while EACH spoke takes a turn resisting vertical loading from squashing the entire wheel. This is not a small task or minor event. The load is often well beyond what one would expect and most would imagine. A wheel beneath a 100 lb rider under certain riding conditions can have the effective load equal to the weight of a non moving small car being placed on top of the wheel. Yes, bike wheels will easily support the non moving weight of a Prius. Load them up under acceleration or cornering and failure is imminent. All the same under you in a pair, with EACH spoke sharing the task and taking a turn at it, things spin on.

    This is a topic I could write for hours or days on. In essence a missing or broken spoke is the quickest way to break other spokes and wobble a rim. As during rotation at a point the spoke which is not there is supposed to be taking a turn at baring the load. A repair job in which removing the tire and tube is the most time consuming part (installing a new spoke is not difficult or time consuming)... being dismissed as not necessary because the wheel has yet to fail is silliness. Pure silliness. In my mind 10 or 1 or 20 gears is absolutely irrelevant to the convo. The spoke taking it's turn of supporting the load is not dependent on gearing. Not to mentioned a single speed is at times mashed more because of lack of gear options than a geared bike, an event putting more load on spokes.

    Replace broken or missing spokes, keep them tensioned equally. Spokes are less expensive than wheels. They have among the most difficult task on your bicycle and always bare the load.
     
    i12ride likes this.
  9. ironlungs

    ironlungs Senior Member

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    I like what you said, sprocket. I'm not spec savvy, that I could never explain it as eloquently (again you're nature!:) ) but I'm mechanically inclined, and can only say, in my own way, that, even as a chain is as strong as its weakest link, so a wheel would be the same. As strong as the weakest spoke. :D
     
  10. GT-Tempest

    GT-Tempest GT-Tempest

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    Its Members like sprocket girl, that makes me love this forum. :D
     
  11. Merlincustom

    Merlincustom Senior Member

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    I think the OP is about 8 years gone, but my advice would be that he was told that by his ex-mechanic.
     
  12. BlazingPedals

    BlazingPedals Member

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    um... you apparently misunderstand how a wire spoked wheel works. All of the spokes are in tension, never in compression.
     
  13. rushlake

    rushlake Member

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  14. rushlake

    rushlake Member

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    Just so I understand, So if you were to take a spoke and set it on the ground pointed up and put a cinderblock on the end there is no compression force on that spoke
     
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  15. MilesR

    MilesR Mom's Taxi Tavern Member

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    Personally I would believe Sprocketgirl being she is a wheel builder.
     
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  16. rushlake

    rushlake Member

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    The whole reason for spokes is because of compression. If the weight of the bike and rider put no force on the rim then there would be no need for spokes.
    Are spokes under tension..... yes. But her point was that as the wheel turns each spoke, in turn, takes the compression of the weight keeping the rim intact.
     
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  17. i12ride

    i12ride Spin Spin Spin Tavern Member

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    Seems like they are tensioned equally to handle the load of a rider and his antics attempting to compress them while the circular shape of the rim fights to prevent that with constantly moving load points.