Wheels - Bladed Spokes

Andy140
Andy140 Posts: 130
edited February 2008 in Workshop
I have wheels that use DT aerolite bladed spokes. Wheels have only covered about 250 miles. While out on Sunday I heard loud twang from front wheel. Checked it at the time and thought all OK. Checked later and found one of the bladed spokes had twisted about 3/4 turn and wheel slightly out of true.

What would have caused this to happen - and what should I do with the spoke?

Thanks

Comments

  • synchronicity
    synchronicity Posts: 1,415
    Get it re-trued, pronto. If you leave it, the wheel will be more prone to spoke breakage.
    vertebr.ae | precision braking & shifting
  • robbarker
    robbarker Posts: 1,367
    When you build a wheel, you normally wind each nipple a quarter of a turn too tight and then back it off - it takes out the twist in the spoke that is wound-in when applying tension.

    It sounds like your wheel builder didn't do this properly, although in fairness, bladed spokes make this harder, which is why I always use round, although I'd like to try bladed one day to develop my skills.

    It may also be that the wheel needs a bit more stress-relieving as well - something that is tricky to do with bladed spokes.

    Increasing and then backing off each nipple 1/4 turn will probably make the wheel more reliable. Personally, I'd loosen all the spokes and start again, but to do that you will need a good truing stand, a spoke key, a dishing guage and (preferably) a tensiometer. And Roger Musson's book from ww.wheelpro.co.uk.

    Or take it to a good LBS who know what they are doing.
  • LangerDan
    LangerDan Posts: 6,132
    For the DT aero spokes you'll also need a holder to stop the spoke twisting. The DTs are made from putty and are quite prone to putting a kink in the spoke where the bladed section changes to circular above the nipple. The "proper" holders support the bladed section for a couple of inches.
    'This week I 'ave been mostly been climbing like Basso - Shirley Basso.'
  • mercsport
    mercsport Posts: 664
    Although not a wheel builder myself , I've been witness often enough to a great local builder finishing off his wheels by placing the wheel on the floor and pressing with all his might down upon the rim sequentially around the circumference to take out that 'wound in' spring within the spoke . Then back onto the jig for a check . And so on .
    "Lick My Decals Off, Baby"
  • robbarker
    robbarker Posts: 1,367
    I've read about people using a 6" bit of wood with a groove sawn into it as a way of holdng the blades of the bladed spokes in the right place while the nipple is turned.
  • SteveR_100Milers
    SteveR_100Milers Posts: 5,987
    I've read a few reviews of Fucrum 3's where the spokes have rotated so badly they are 90 degrees out of alignment! I guess its a trip to an LBS to fix? My wheel truing skills are pants at best...
    http://www.pontypoolrcc.co.uk/
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  • fenlandplodder
    fenlandplodder Posts: 230
    My attempts at building with Aerolite spokes suffered badly for this problem despite trying to unwind the spokes as I built the wheelt. I think neither attempt lasted 400 miles before I decided a rebuild was needed. I'll probably stick to round spokes in future.

    Interesting info about the special DT spoke holding tool .
  • aracer
    aracer Posts: 1,649
    LangerDan wrote:
    For the DT aero spokes you'll also need a holder to stop the spoke twisting. The DTs are made from putty and are quite prone to putting a kink in the spoke where the bladed section changes to circular above the nipple. The "proper" holders support the bladed section for a couple of inches.
    The trouble is, such a holder won't support the part where the blade changes to circular, so I don't see how it can do anything to help with that problem. I have such a holder (Sapim version), but didn't use it when I built as I realised it wouldn't actually do any good.

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