wheel tuneup?

neeb
neeb Posts: 4,470
edited August 2010 in Workshop
I have a set of lovely Eurus wheels that are three years old with a five-figure mileage on them. I've serviced the hubs a couple of times but the rims are still completely true. What I'm wondering is whether it would be worthwhile tightening up all of the spokes a little and maybe getting the wheels balanced. None of the spokes are loose as such, but a few give quite a low frequency sound when pinged. I'm reluctant to fiddle with the spokes and maybe put the whees out of true/round unnecessarily however. The rear wheel has the G3 spoke pattern, so I guess with that one at least it wouldn't just be a case of tightening each spoke by the same amount, the single non-drive side spokes are presumably at a different tension from the dual drive side ones?

Comments

  • freehub
    freehub Posts: 4,257
    If it ain't broke don't fix it, if the wheel is true, and is not making noises when putting pressure on it, like going up hills or something, then leave it be.
  • John.T
    John.T Posts: 3,698
    The idea of the G3 spoking at the rear is that one non drive side spoke is balanced by 2 drive side ones so the tension is closer. It is a good idea for the rear but rubbish on the front.
  • balthazar
    balthazar Posts: 1,565
    There is no general change in the structure of a wheel over time. The best you can hope is that the wheel stays true, and is otherwise no trouble, until the rim wears out. Thast is the case here so there's nothing for you to do: moreover, fiddling with spokes for no reason would likely cause problems.
  • neeb
    neeb Posts: 4,470
    Ok, I'll leave them alone!

    Makes sense - I guess if any spokes had loosened it would cause the wheel to go out of true. I was just wondering if the wheels could be made a little stiffer by tightening them up, but if it ain't broke...

    Must say I've been amazed at the service I've got out of the Eurus and how they have remained true. Also my brake blocks seem to last for ages, which I guess is a good sign re: rim wear. I put that down to not using this bike for commuting or urban riding.
  • balthazar
    balthazar Posts: 1,565
    edited August 2010
    neeb wrote:
    I was just wondering if the wheels could be made a little stiffer by tightening them up, but if it ain't broke...
    Spoke tension has no link to wheel rigidity: As long as the spokes are tensioned at all, then overall rigidity is a material characteristic which is unchanged, regardless of how highly you tension the spokes.

    Spoke tension does have consequence for wheel strength, however: higher tension=stronger wheel. By stronger, I mean that it is able to endure higher loads without leaving the rim unsupported and vulnerable to bending. Hence, the advocation to use the highest tension that the wheel components (usually, the rim) can bear. In any case, your wheels have done well as they are.
  • rake
    rake Posts: 3,204
    id give them all a tweek, theyre bound to have stretched a little.
  • John.T
    John.T Posts: 3,698
    rake wrote:
    id give them all a tweek, theyre bound to have stretched a little.
    They may have bedded in a bit but are unlikely to have stretched. They are not that tight.
  • neeb
    neeb Posts: 4,470
    Spoke tension has no link to wheel rigidity: As long as the spokes are tensioned at all, then overall rigidity is a material characteristic which is unchanged, regardless of how highly you tension the spokes.

    Spoke tension does have consequence for wheel strength, however: higher tension=stronger wheel. By stronger, I mean that it is able to endure higher loads without leaving the rim unsupported and vulnerable to bending. Hence, the advocation to use the highest tension that the wheel components (usually, the rim) can bear. In any case, your wheels have done well as they are.
    That's quite interesting. So with low tension (low strength) the spokes on the lower part of the wheel could become un-tensioned given a high enough load?

    Can you explain why rigidity is not increased by greater tension? It's sort of counter-intuitive.
  • balthazar
    balthazar Posts: 1,565
    neeb wrote:
    Spoke tension has no link to wheel rigidity: As long as the spokes are tensioned at all, then overall rigidity is a material characteristic which is unchanged, regardless of how highly you tension the spokes.

    Spoke tension does have consequence for wheel strength, however: higher tension=stronger wheel. By stronger, I mean that it is able to endure higher loads without leaving the rim unsupported and vulnerable to bending. Hence, the advocation to use the highest tension that the wheel components (usually, the rim) can bear. In any case, your wheels have done well as they are.
    That's quite interesting. So with low tension (low strength) the spokes on the lower part of the wheel could become un-tensioned given a high enough load?

    Exactly. In that case, the rim is unsupported by spokes, and is extremely vulnerable to bending laterally. The form usually taken is that of a "pringle" or saddle shape, viewed edge on: the top of the rim moves in the same direction as the bottom (loaded region), and the middle moves the other way. There are fine illustrations of the transitional states in Jobst Brandt's book "The Bicycle Wheel". High tension spokes are reduced to a slack state later, hence they result in a stronger wheel.
    Can you explain why rigidity is not increased by greater tension? It's sort of counter-intuitive.
    Wheel deflection is defined in terms of spoke elongation: that is a material characteristic of the steel used to make the spokes. The initial tension of the spoke has no effect on the elongation in response to load, which maintains a constant ratio (practically speaking), at least until the spoke nears its yield (failure) point – something which never happens in ordinary bicycle wheels, because rims "pringle" first. I agree this is counter-intuitive: such is intuition!
  • dennisn
    dennisn Posts: 10,601
    rake wrote:
    id give them all a tweek, theyre bound to have stretched a little.

    -1... That sounds like a line from the "fix it until it's broke manual".
  • Monty Dog
    Monty Dog Posts: 20,614
    Is this where we start a debate about whether the hub 'hangs' from the upper spokes or 'stands' on the lower spokes :wink:
    Make mine an Italian, with Campagnolo on the side..
  • balthazar
    balthazar Posts: 1,565
    Monty Dog wrote:
    Is this where we start a debate about whether the hub 'hangs' from the upper spokes or 'stands' on the lower spokes :wink:
    That's fightin' talk..!
  • neeb
    neeb Posts: 4,470
    Wheel deflection is defined in terms of spoke elongation
    Trying to get my head around that. Intuitively it seems that it should be defined in terms of spoke bending, but I can just about see why it might not be if we are talking deflection in the sense of the top of the rim moving laterally in one direction and the bottom in the other (as opposed to "pringling" where they move in the same direction and the spokes presumably bend).
    Jobst Brandt's book "The Bicycle Wheel".
    I've been meaning to buy that book for years - now might be a good time!

    P.S. I gave the wheels a very thorough clean last night to satisfy my urge to apply some form of TLC. :wink:
  • balthazar
    balthazar Posts: 1,565
    @neeb: the book's hard to find, sadly- I don't think there's a recent print. It's well worth trying to find it though- it'll answer all your questions on the subject. Good luck! And enjoy your clean wheels