Preventing spokes unwinding

[fatboy]

On my Audax bike the rear wheel is a pain in that some spokes unwind (NDS). It's 32 spokes with double butted on the NDS and plain gauge on the drive side. The rims are Magic Open Pros and I built it. I've done other wheels before and never had this happen. The wheel has lots of tension (I tried adding some more and it pringled).

Any suggestions? Loctite?

[Brucey]

yes Loctite will work. If the threads are not greased you can add a fluid grade of threadlock at the square end of each nipple, spin the wheel, and it will penetrate where it needs to go. It is also possible to add an adhesive to the slotted end of the nipple and if the spoke is both clean and protruding, this adds some locking action too.

Lightweight/flexy rims are prone to this kind of trouble because the rim moves around more. Anything you can do to reduce the wheel dish and/or improve the spoke angle will help too.

cheers

[Freddie]

Wouldn't double butted spokes all round be better (re unwinding) for a lightweight rim and better still, thin gauge DT Revolution spokes? Revolution spokes are rather expensive though.

[fatboy]

I'll get some loctite.

I tried Open Pros to avoid Chrinras and the hell that is getting tyres on and off. Don't think there's anything to be done about dish as the frame is spaced for road hubs.

[Brucey]

ah but there's 'road hubs' and 'road hubs'....

cheers

[fatboy]

ah but there's 'road hubs' and 'road hubs'....

cheers

?????

[Samuel D]

What hub is it? Shimano ones have wide bracing angles but that tends to result in the left spokes having a low tension.

More to the point, 8/9/10-speed hubs have better geometry than 11-speed ones. Unless you’re using an 11-speed cassette you’d be wise to seek out an older hub.

[Gattonero]

ah but there's 'road hubs' and 'road hubs'....

cheers

?????

Not all the hubs have the same measurements.
Broadly speaking, the closest is the Rh flange to the middle of the hub and the farthest is the Lh flange, the more difference you will get in spoke tension between the two sides.

You cannot put more than 110-115kgf on Open Pro's unless you want to crack the eyelets.
I'd say you better loosen up all the spokes and start from scratch, do the Rh ones to 80% of the max tension, then do the Lh ones with low-strength Loctite (grade 222 or 223) and true up the wheel QUICK before the threadlock will set.

You may consider asymetric rims in future, they give some help in reducing the difference in spoke tension.

[mercalia]

strange none of my wheels suffer from spooks unwinding. what causes it in the first place? The ones I build dont have super high tensions on the spooks some where between the original and the SPA one I have. Even the original wheel spokes didnt unwind

[Gattonero]

strange none of my wheels suffer from spooks unwinding. what causes it in the first place? The ones I build dont have super high tensions on the spooks some where between the original and the SPA one I have. Even the original wheel spokes didnt unwind

There's so many variables that a generic description cannot give any answer.

There's people who needs to true their wheels every few months and break spokes every so often even on symmetric wheels (i.e. front wheels or track wheels), and there's people who never break spokes or need to true their wheels. There's wheels which are prone to flex more and/or are not built with even spoke tension, or incorrect lacing, or wrong spoke length.
The list goes on....

[fatboy]

Sounds like my choice of rim! This is the only wheel that I've had spoke unwinding issues, but to be fair it's the first rear road wheel that I've built, I've done road front wheels and tourer rears.

Last night I took it back to square one and it's true, round and with fairly even spoke tension (by feel and pitch as I don't have a tension gauge).

[andrew_s]

then do the Lh ones with low-strength Loctite (grade 222 or 223) and true up the wheel QUICK before the threadlock will set.

There does exist a grade of thin loctite that will wick into the threads after the wheel is built.

The stuff I use says "Anti-Shake, prepared exclusively for X-Lite by Loctite", but I got it quite a long time ago. It actually makes the spokes easier to take off when the rim wears out, as it keeps the road crud out of the threads.

[Gattonero]

Yes I know that stuff, but it doesn't work that well and is usually more expensive. The reason why the spokes are easier to remove is because it cannot penetrate that much, if you look at the spoke thread there isn't much coverage done by the threadlock compound.
To apply the threadlock onto the spokes thread prior lacing is still the best option; alternatively it can be applied after lacing, on the portion of spoke thread sticking out of the nipple (as you lace the wheel with only a couple of turns of the nipple onto the spoke thread) and on the opposite end by the nipple head, letting one drop flowing inside the female thread.

[Brucey]

there is a small 'well' between the nipple and the spoke, (which will hold a small amount of threadlock provided it isn't already full of something else); spinning the wheel vigorously will force the threadlock into the (dry) threads.

IIRC the force (in 'G's) is given by
(v^2)/(9.81 x r)

with r in m and v in m/s.

So at a rim speed of 10m/s ( roughly 20mph) on a 700C wheel rim the load is about 30G. At double this speed ( easily acheived by spinning the wheel up in top gear whilst the bike is suspended e.g. in a workstand) it is ~120G. Needless to say this is 'highly effective' in causing any liquid threadlock to penetrate dry spoke threads.

cheers

[Gattonero]

That is very optimistic, in reality doesn't work that well and the threadlock will spill all around outside the nipple before going inside it.
Capillary action will work better than G-force, and wetting the threads beforehand will work even better.
The threads on a 14g spoke are 56tpi so they're rather fine indeed, hardly any room for a compound to move in. Those "nipple freeze" compounds are low-viscosity threadlocks, so they're prone to drip everywhere, and one can see how easy is for this compound to flow away rather than waiting the "g-force" to push them into the threads.
In fact, those compounds are often best applied by the inside of the rim, where they can get the thread and hopefully something will get inside.