Rusty Nipples (ok corroded, but where's the drama in that?!)

[lpretro1]

This is the one
http://www.chainreactioncycles.com/...gclid=CNC5iIbOh8wCFTUW0wod7GAL2g&gclsrc=aw.ds

 

[Yellow Saddle]

Now that you've bottomed out the OP's solution/options, please can you share your insights into 'evil'.

Why would wheel builders do that? Is there any risk spokes will spontaneously loosen? The challenge the OP has had, given his spokes are straight pull, makes it seem particularly unwise in such spoke design.

There is no need for threadlock on properly-tensioned wheels because the friction in the nipple/spoke thread interface is high enough to prevent nipples unscrewing spontaneously. Threadlock complicates repairs and minor tuning down the line, sometimes to the point of having to cut the spokes in order to turn a nipple a few quarter turns.

Wheelbuilders to it because their wheels are built my machines that cannot attain high spoke tension. Once a spoke has attained reasonable tension, the spoke starts to twist (because of the aforementioned friction) and machines can't detect that twist and compensate for it. Wheelbuilders either mark the spoke and watch for the mark to move or, intuitively after building hundreds of wheels, compensate for the twist without even looking. They do this by advancing the nipple say 3/4 turn and then backing off by 1/4 before moving on to the next spoke. Machines start to "hunt" for the right position at very low tension.

I have described nipples unscrew on low-tension wheels as spontaneous, but that is just a figure of speech. It is not spontaneous but happens from a predictable action. To understand this you have to understand that a wheel in use has lower spoke tension in the contact patch area, called the load affected zone than anywhere else. The load affected zone moves along the wheel at the contact patch and reduces spoke tension in that spot by pressing between rim and hub. The spoke tension everywhere else in the wheel remains the same. Most people don't get this, hence my abandonment of a previous thread here where a gang of non-understanders mobbed me. Anyway, if the load affected zone is say, three spoke intervals long and the load on that wheel is say 60kgs, then those three spokes will lose the collective tension of 60kg (600N). If each spoke had a tension of 1000N to start off with, you'll agree that the new tension in "the zone" reduces by 600/3 for each spoke or 200N each, leaving the spoke with 1000-200=800N of tension. This is more than enough to keep the nipples tight during that cycle of unloading. However, if you start off with say only 250N in that spoke to begin with, you can see what happens when the spoke unloads. There will be only 50N margin in there that is easily exceeds when you hit a bump or hop a pavement. Once the spoke has low enough tension, the nipple can unscrew against the now-reduced friction. It will never go tighter, only looser, according to the Le Chateleur principle. I've hinted to that previously when I said one only tighten, never loosen a spoke in a wheel that was true but has developed a wobble.

There is another issue here as well. If a spoke is in torsion, when its tension reduces during riding, the torsion will also self-reduce. This happens by the spoke twisting in the nipple, obviously unscrewing it in the process.

Threadlock is evil because:
1) It complicates things down the line.
2) It is a cop-out for poorly built wheels.
3) It is an indicator of under-tensioned machine-built wheels.


Edit: Sorry, I had to fix a small error. The example above had 50kg load on the wheel instead of 60kg. All fixed up now. Thanks to the math fairy who pointed it out.

 

[fossyant]

Hand built wheels never use threadlock as the wheel is tensioned properly and this takes time. I've built a few wheels and it's time consuming, but get it right and you have wheels that run true.

Mass produced wheels are usually tensioned by a machine.

Do you have any white powdery deposits on the nipples. I've never had an issue with the threadlock on Aksium or Ksyrium wheels. If you've got powdery deposits, think about how often you've been cleaning the wheels, especially through winter.

 

[alvintc]

Just to update this.. Tightened & trued without any real issue.

I used a park 3 way tool to get the internal nut & pliers to hold the spoke while I tightened. No problem at all however there has to be a better way than holding the spokes with pliers!

How are you meant to hold straight pull spokes while tighening them?!

 

[fossyant]

I use an adjustable spanner to hold the bladed spokes (not that I've needed to true the wheels often). There are plastic tools, but I've not got one.

 

[alvintc]

Problem there is that mine are round!