Damned Snapped Spokes

Discussion in 'Cycling Equipment' started by sapper3491, Sep 30, 2006.

  1. sapper3491

    sapper3491 New Member

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    I bought my first road bike in ealry summer 2006. Its a Bianchi Via Nirone. I paid about £650 for it so its a basic model. I've done a few miles on it but never abused it. For the first 2 months everything was fine until on one occasion i was pedaling very hard uphill and i heard a snap and noticed one of my spokes had snapped. I took it to my local shop and they replaced the spoke and trued the wheel. One week later while pedaling hard another spoke snapped. So i had it fixed again. Then it happened once more and since then the bike has been i my shed for the past month while i sulked. Can anyone advise on why this might be happening? And what i can do to rectify the situation.

    Any help would be much appreciated!
     
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  2. bigkev

    bigkev New Member

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    the spokes must have been over stretch or just cheap and nasty spokes



     
  3. Xsmoker

    Xsmoker New Member

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    Perhaps some more information would help. What is your weight? I believe the wheel set is Joytech/Ambrosio. I can't seem to find any info on them. What is the spoke count and lacing pattern of the rear wheel?
     
  4. terry prowse

    terry prowse New Member

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    could be any number of things.1/ poor quality spokes.2/over tight spokes.3/ your weight.4/ the way the wheel is laced. and some more. I suggest that you check to see what the lacing patten is on your wheel ( I assume rear) if it's 4 cross drive side and either 2or3 cross on the other side, then your spokes are to tight. also check to see if the chain has jumped off the cluster and into the spokes at some time. if so replace all drive side spokes. there's other possibilites but go with these as a start. Regards terry [email protected]
     
  5. IEatRice4Dinner

    IEatRice4Dinner New Member

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    there was a problem with bad batches of spokes on stock bikes... i know fuji was affectes there was a few others... ask the bike shop to relace the wheel with dt swiss or wheelsmith or somethin
     
  6. sogood

    sogood New Member

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    OP really need to tell us what brand and model of wheel was included on his bike.
     
  7. dhk2

    dhk2 Active Member

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    Assuming you don't weigh 300 lbs, and aren't abusing the wheels by jumping curbs and slamming over every pothole you can find, would conclude that your Bianchi came with a junk wheelset. You can drive yourself crazy chasing broken spokes when what you need is a better set of wheels.

    Ask the LBS to replace or rebuild them for you under warranty, or at least get you some break on a more suitable replacement set.
     
  8. Bro Deal

    Bro Deal New Member

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    When you break one spoke on a badly built wheel, more will follow. Just replacing the broken spokes is like putting a BandAid on a gunshot wound.

    You have two choices. One is find a competent LBS that can rebuild the wheel with properly tensioned and stress relieved spokes. The second choice is to buy a new wheelset--or maybe just a new rear wheel. A set built with Shimano 105/Veloce hubs and Velocity Aerohead rims should not cost too much.
     
  9. Retro Grouch

    Retro Grouch New Member

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    I'm betting that the broken spokes are on the non-drive side of the rear wheel. Often times those spokes have inadequate tension and, as a result, break due to stress cycle differences during each revolution of the wheel. Replacing the broken spokes and retrueing the wheel doesn't solve the problem because the underlying cause (inadequate tension) hasn't been corrected.

    If that's the case, the solution is to have the wheel rebuilt with all new spokes. It is vitally important that the spokes be adequately tensioned and seated during the building process.
     
  10. ScienceIsCool

    ScienceIsCool New Member

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    I'm sorry you're having such awful luck with your wheels. This does give something interesting for the rest of us to think about though.

    Why would a relatively new spoke break?

    One reason would be if the spoke was put under enough tension that it exceeded its yield and snapped! Kind of like pulling a rubber band until it breaks. This is highly unlikely/impossible for several reasons. Spokes are placed under tension when the wheel is built and the failure would have happened then. During normal use, a wheel's spokes go through cycles where the tension is reduced (not increased). And lastly, a normal aluminum rim will deform and break (i.e., spoke rips through eyelet) before the spoke will yield.

    The second reason is a fatigue failure. This can occur because of the continuous loading and unloading of the spoke tension while you are riding. These stress cycles cause normal (microscopic) voids and nucleation sites inside the spoke to grow until a crack works its way through the spoke and it breaks. Fatigue failures are greatly accelerated if the spoke becomes totally slack under load or is too close to yield. Again, too close to yield would mean a busted rim, so it's more likely that the spokes don't have enough tension. This should be easy to check.

    The last reason I can think of is that the spokes themselves are of a poor quality. That is, they have residual stresses due to the manufacturing. Or there are material defects, impurities and inclusions. All these things could also lead to accelerated fatigue.

    Your spokes are breaking regularly which means that they are all near the end of their fatigue life whether it's poor tension or crappy spokes. I'd say rebuild the wheel with new spokes and all should be well... :)

    John Swanson
    www.bikephysics.com
     
  11. Bro Deal

    Bro Deal New Member

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    Machine built wheels, which cheap wheels are likely to be, are notorious for under tensioned spokes. The machines also do a poor job at stress relieving.

    There are a lot of wheels on the market that would be a lot more durable if they were touched up by hand before being used.
     
  12. FREDBLACK

    FREDBLACK New Member

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    What is stress relieving? sorry for the ignorance.


     
  13. ScienceIsCool

    ScienceIsCool New Member

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    Fun as it sounds, stress relieving isn't a weekend away... :) Good question, though. What is stress relieving. When a spoke is made from a coil of wire it is straightened, threads are rolled onto one end, and bent at the other to give it an "elbow". These processes can leave "residual" stresses in the material.

    If left unchecked, those residual stresses can lead to premature fatigue failures. This is why your spokes will typically fail at the elbow, but never in the middle. It would be great to get rid of those residual stresses, which is called stress relieving.

    How do you do it? Once the wheel is laced, but before the spokes are tensioned, you grab pairs of spokes and give them an almighty squeeze. This will bend (yield) the spoke a bit at the elbow. By taking the material past yield you actually remove the stresses. Now the spoke will last much longer.

    John Swanson
     
  14. FriendlyFred

    FriendlyFred New Member

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    I had the spokes breaking problem like crazy on a Specialized Sequioa with stock wheels (my first road bilke)b. Every freakin' time I went to climb or descend a good hill, bang, a spoke would go. I'm 5'10"/ 160 and not a pounder on the pedals....these spokes would just go. After a complete re-build, and spokes going yet again, Specialized replaced the wheels with an upgraded set. No more problems. At the time, I was told there were known issues with a number of stock wheelsets (this was two years ago). There's just nothing qite as fun as having a spoke blow when you're doing a hill (up or down) 15 miles from home.
     
  15. sapper3491

    sapper3491 New Member

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    Hi Thanks everyone for you help and suggestions. I have cut and paiste the information for the bike below for those who wanted a wheel spec. My weight is around 200lbs which is about 90kgs, so i guess i'm carrying a bit, but thats why i bought the bike. All of the spokes have broken on the rear wheel on the cassette side. Went to my local bike shop today and he reccommended i purchace a new "Mavic" wheelset - MAVIC AKSIUM ROAD WHEEL SET £120 all in for front a rear wheel. They said they could use my existing cassette. What do you all think?? Thanks again for all your posts!
    Andrew
    Bianchi Via Nirone 7 Aluminium Xenon Compact Drive 2006 Road Bike

    Frame: Bianchi Via Nirone 7 Aluminium Double Butted
    Forks: Bianchi FLN carbon/ Aluminium
    Gears: Campagnolo Xenon mechs
    Shifters: Campagnolo Xenon
    Chainset: FSA CFJ-215 Compact with 50/34 tooth chainrings
    Brakes: Bianchi AG-452
    Wheels: Bianchi Componenti racing wheel set
    Tyres: Continental Ultra Sport
    Handle Bars: ITM 330 Super Over bars
    Stem: Bianchi Forged Super Over
    Saddle: Selle Italia Initiale
    Seatpost: Bianchi SP-151
     
  16. sogood

    sogood New Member

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    I would,
    1) Get them to explain the real reason for spoke breakage. If they all broke, then it's perfectly possible there's a manufacturing batch issue. In which case you'll be able to claim under warranty.
    2) If it's truely your weight, then a set of custom wheel might be the better bet in terms of durability and repairability. I am no expert, but you can choose one that has more spokes to improve the durability.
     
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