A gummy [spoke] nipple freeze that doesn't really set?

[Valbrona]

Any ideas?

Thanks.

[Brucey]

some folk use linseed oil.

cheers

[pwa]

Isn't this one for the "Health and fitness" section?

[Gattonero]

Loctite 572 is a "gasketing" compound that works well on spoke nipples, bear in mind it's a bit thick (meant for coarse threads) so needs the spoke threads to be dipped in because it won't really move. Leaves good time to go around tensioning and truing the wheel.

[Mick F]

Do some spokes have a tendency to unwind?
If so, why?

[Brucey]

Do some spokes have a tendency to unwind?
If so, why?

usually because they go momentarily slack (sometimes completely slack) when the wheel is in use.

cheers

[Mick F]

Next question.
Why on earth do they sometimes go slack?

[Cavemud]

Take a look at DT Swiss Pro Lock Nipples.

I've been using these for years now and they're great once the wheel is built, but it makes the tightening and truing process much slower.

[NickJP]

I've been building wheels for 40+ years, I never use anything but oil on the nipples, and no-one has ever come back to me and complained that the spokes came loose. If I'm using DT Squorx nipples, which have the pro lock compound on the threads, I dump them in oil as well before using them.

[Mick F]

Nowhere near the experience of you, but I too use a little oil.
I cannot for the life of me envisage a scenario where spokes would become slack.

[Carlton green]

... I too use a little oil.
I cannot for the life of me envisage a scenario where spokes would become slack.

Another here who uses a little oil, though I now wonder whether it should be vegetable rather than mineral based.

As I understand things the spokes in an unloaded wheel are all in tension and slightly stretched, but when a wheel is used to support weight the supporting spokes (at and towards the top of the wheel) stretch more under the additional load and that allows the opposite non weight supporting spokes to contract and become less or even unloaded. When spokes are tensioned by twisting the nipple the thread friction in that action also puts a twist into the spoke, the spoke is acting as a spring both in tension and in torsion. When tension is reduced the torsion spring element tries to un-wind the nipple and to some greater or lesser extent succeeds (if the nipple is free-ish to rotate on the spoke). The way around those two problems is to have spokes so tight that they are always under tension when the wheel is load supporting (but not so tight that they break in use) and to allow the spokes to de-twist in a controlled way.

I hope that the above helps and that my understanding isn’t too far adrift from what the better informed believe.

[Brucey]

Next question.
Why on earth do they sometimes go slack?

Because you push hard on the pedals and move your weight around on the bike.

Nowhere near the experience of you, but I too use a little oil.
I cannot for the life of me envisage a scenario where spokes would become slack.

If you do nothing but sit in the saddle and don't push hard on the pedals you can get away with all kinds of things. Otherwise it happens all the time. If you respect the maximum tension limit on a lot of rims on the DS of a derailleur rear wheel the tension in the NDS spokes is only ~60% of this (and might be ~60kg) and is easily overcome if you are a strong rider.

A lot of supposedly experienced wheelbuilders just overtighten the spokes until there is sufficient tension in the NDS. The rims then often crack and are declared 'rubbish' by all concerned.

Fortunately thin oil in the spoke threads doesn't persist that long and nipples tend to seize up over time. However if you use a really good lubricant (eg a heavily loaded MoS2 grease) then the nipples can still back out even years later if the wheels are subjected to hard use.

All 'factory' wheelsets with low spoke counts come with threadlock on the nipples, and this is absolutely necessary if the wheels are to be subjected to any hard use. Note that you will still get some locking action rather than none even if the spoke thread is contaminated with oil.

A reasonable compromise is to build using lubricant on DS nipples, nipples in undished wheels and left side nipples on front disc brake wheels, and leave NDS nipples, and RH nipples in disc brake front wheels dry when the wheel is built. A wicking threadlock can then be used on the dry nipples after the build; this helps locking, helps prevent water from getting into the nipple threads and yet doesn't prevent disassembly/adjustment later on. Also, it isn't a bad idea to lubricate the rim drillings (where the nipples seat) with grease when building; this allows an easier build and helps to delay the onset of corrosion and cracking in the rim itself.

Linseed oil works as a thread lubricant during the build and (over weeks or months) dries to a kind of varnish, which works as a threadlock. I've dismantled wheels that were decades old which (accidentally or deliberately, I'm not sure which, it may have been hub lube overspill) have had dried vegetable oil on the spoke threads. All the nipples have unscrewed in such wheels (with reasonable breakaway torque) and you could still smell the (linseed?) oil still even though it had dried to a brownish resin.

If you want to see how easily (or not) you can make spokes go slack just hold the rim to one side and pluck the spokes. Note that whatever lateral load causes the spokes to go slack (and they don't need to go fully slack for the nipples to back out if they are well lubricated) this can diminish to about half that value when the wheel is under the highest torque loading and seeing a vertical load too. Normally the lateral load in the static test is ~10 or 20kgf or so; you don't need to be a very strong rider to exceed this value in an uphill sprint.

Thus the spokes which are most likely to go slack are the NDS 'pushing' spokes. A further complication is that the spoke tension in some rims drops appreciably when the tyre is inflated; this is quite a lot to do with how the rim changes shape when the beads are pushed sideways rather than the global stiffness of the rim; some rims lose about 10kgf (even with DB spokes) so it is always worth checking for this when building unfamiliar rims.

With quite a lot of lightweight rims, with a low tension limit (that is respected), to be ridden by an aggressive rider, I would regard it as 'almost impossible' to build reliable wheels with well-lubricated nipples.

cheers

[Mick F]

Define "slack".
It must be me considering that slack means slack.
Low tension, is a different thing.

[Brucey]

slack in this context means 'slack enough' and that varies; not all nipples spin as easily as others.

Arguably the better you build your wheels, the more likely the nipples are to back out at any given tension/lubrication state. The reason for this is that properly stress-relieved wheels have spokes that are set correctly so that they are seeing no bending stress and the nipples will be in a straight line with the spokes too. Badly built wheels (from a spoke fatigue perspective) have nipples that bind because the spoke is going into them at an angle and a nipple that is not free to turn in the rim. The spokes are also not set to the right shape, so even when they go slack in tension, they want to spring sideways; this may hinder the nipple backing out as well.

Service conditions are a big factor too.

Years ago I built two near-identical wheelsets; one for me (with SS DB spokes) and one for a chum (with SS PG spokes). They were the same otherwise, and had brass nipples lubricated with a persistent grease loaded with solid lubricants. After many years of foul-weather riding, the rims on my chum's set wore out and were replaced. 'How the hell did you build those wheels like that?' he asked me. 'They stayed perfectly true and when I came to re-rim them the nipples came undone very easily' he went on. 'All the other wheels I've tried to re-rim have had really badly seized nipples and these didn't'. I explained that I'd used a special grease on the spokes before building.

What I didn't tell him was that my similar set of wheels had lasted exactly one ride; admittedly it was a hard ~120 mile ride, but it was still only one ride. The NDS spokes had started to back out in the rear wheel. This was despite the fact that DB spokes ought to have been stretchier and less prone to going slack. To stop the backing out, I had to clean the grease off the NDS spoke threads, use new nipples and slightly exceed the recommended tension on the DS. I just about got away without using threadlock on the NDS nipples, and that was probably because I'd used less dish in the wheel than you would normally have with that type of hub.

The conclusion was that the difference came from the service conditions; I just gave the wheels much, much more stick than he did.

cheers

[Gattonero]

I've been building wheels for 40+ years, I never use anything but oil on the nipples, and no-one has ever come back to me and complained that the spokes came loose. If I'm using DT Squorx nipples, which have the pro lock compound on the threads, I dump them in oil as well before using them.

You got your anwer there