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As above, back wheel, no previous issues with tension. I trued it 6months ago. Under a year old.
Local, short 15km ride.
Half of them borderline 'floppy'.
I'd go over your hub and rim with a fine tooth comb, sounds to me like something may be about to give way.
Was the tension not sufficient and all the nipples loosened or are the nipples pulling through the rim?
Front or rear, left or right?
As above, eliminate reasons for catastrophic failure e.g. cracking around rim holes, otherwise spoke tension not high enough. Have you converted the wheels to tubeless? Tubeless put a big inward radial stress on the rim meaning that spokes need to be increased in tension to compensate. I just built some new wheels, stress balanced etc - mounted and inflated the new tyres to then find that the spokes were now below tension and had to re-tension them.
Tubeless put a big inward radial stress on the rim
I don't see how the stresses on the rim and spokes would be any different between tubed and tubeless.
Bead used to easily sit under hook and it was mostly sideways forces. Now, the bead sits on a shoulder and is a tight fit. That causes in inward forces (and the rim does equal and opposite to the rim).
In a regular wheel with a tube, the tube is forced against the rim by air pressure, causing an inward force. The exact same inward force will also act on the rim in a tubeless tyre because the rim tape is forced against the rim by air pressure. Absolutely no difference in the stresses as far as I can see.
If you care to google you'll see that quite it's quite common for rims at the lighter end of the scale, with tension dropping as much as 10-25% with some tubeless rims - the accepted practise is now to retension the wheel with the tyre installed and inflated
nonsense. The stresses will be exactly the same tubed or tubeless. Basic physics
Tubed.
Nipples loosened.
About 120* of the wheel had all the non drive side loose, one on dive side.
I thought goosed flange (s****) or bust/bent rim, but I've inspected carefully, tightened it all up, back straight and been back out for another 10k..All fine.
The only thing I had domes was fit new tyres, and whacked up pressure initially as they didn't seat evenly, then dropped pressure to ride.
Last user of the bike was eldest_oab, so I'm wondering if he has done some massive jump/sideways landing on it. I didn't do m-check this morning, so they may have been loose. I did do a clean & service on it a week ago...
It has always been the case that high pressures in tyres could reduce spoke tension. I suspect that the move to lighter weight rims happening the same time as the take-up of tubeless has conflated the two and why it's now considered to be an issue at lower pressures too.
Matt,
Happened to me a couple of weeks ago, washing the bike and noticed quite a few spokes on rear wheel, non drive side loose, too bad to ride so spoke key out, tightened up and ride OK, but last ride heard a noise, on closer inspection there is a ding in the wheel and a crack at the spoke eye, so new rim required, whole wheel needs some TLC tbh. Wheel about 2-3 yrs old hope hoop, bike older, so the odd creak is to be expected. Tubeless btw and I don't do jumps, hardtail 29er.
So still not sure, but perhaps had been working loose for a while and not noticed, washing and maintenance is good to keep us on the trails. Having said that I rode High Street with the wheel yesterday and survived;)
As I understand it, aside from rim and spoke hole damage, if a few loosen it can rapidly affect the tension of others. Times I've seen this has been with off the shelf wheels that haven't been bedded in (one myself I own included).
Tubeless put a big inward radial stress on the rim meaning that spokes need to be increased in tension to compensate.
…
the accepted practise is now to retension the wheel with the tyre installed and inflated
First I've heard of this and not one wheel builder I've used or that I'm aware of friends using has ever asked about tube or tubeless or advised retensioning for tubeless.
That said, majority of rims are tubeless ready these days, though that's mainly about the rim bead hook design.
Have used tubeless on cheap non tubeless rims I've ghetto converted, and never an issue, never retensioned, held true for years.
As said, tube is using air pressure in the tube to push the tyre onto the rim. Tubeless is using air pressure alone to push the tyre onto the rim.
p.s. I'm talking mountain bike wheels here of course, this being "Singletrack"world 😉 . High pressures of road tyres, maybe it's all different.
I wouldn't assume it all happened in one ride, more likely it's been happening for a while but it just got to a point where it's noticable- wheels can be surprisingly loose and still work fine. And the looser it gets the faster it loosens because tension is one of the things that keeps it tensioned.
I "suddenly" discovered my rear wheel in the remedy was basically all tuned to low E last time we were in Wales, with some absolutely slack... But I guarantee it'd been like that for a while, it's just that I hadn't noticed. I noticed it in the garage not on that day's uplift.
Plenty of "expertise" from non-wheelbuilders here 😉
Assuming nothing is damaged (rim deformed around spoke holes, cracks, hub damaged etc) then I would assume it has been coming loose, reached a low tension, rapidly loosened and become apparent.
The large drop in spoke tension on tubeless rims/tyres is due to the tyre bead acting on the rim, not the air pressure. You can see this as the tension will remain lower with the tyre deflated, then jump up when the bead is broken.
Some rims loose tension as soon as you inflate a tyre. As previously mentioned, it might have been like this for a while.
i'm not super experienced at wheel building, but built a dozen or so wheels with no issue. A stans arch ex though went completely loose on one side with the tyre inflated. It lost around 20kgf of tension.
What tension do you run your spokes at? Maybe they have always been borderline on the non drive side and a bit of extra pressure or riding over something a bit harder had passed them over the edge?
I don't have a spoke tension guage - just spoke key, pencil taped on chainstay and 'squeeze' spoke pairs to check tension.
I think I will send the wheels up to Martin at Roots Cycles for a tighten...
Plenty of “expertise” from non-wheelbuilders here
plenty of “expertise” from people without a basic grasp of physics too.
I build wheels, and retensioning for tubeless is utter bollocks.
A spoke tension guage isn't a bad thing to have really. It's not so easy to get rear wheels tensioned up properly as the drive side can feel too tight so you back off and make the non drive too loose
Plus it's another tool 🙂
I think I will send the wheels up to Martin at Roots Cycles for a tighten…
Good idea I think. As it's the non drive side it was probably just a little low on tension and worked loose.
I am no expert but I do have Roger Musson's book and on the subject of tyres reducing spoke tension he says spoke tension is likely to drop a little when a tyre is installed and inflated but this is not something that has caused him to add spoke tension. To me that sounds like it could be a problem if you've gone a little light on your spoke tensions in the first place
On road tubeless with a stans rim, spoke tension does decrease when the tyre is fitted.
It's due to the tightness of the bead (which is ridiculously tight) on probably the lightest clincher rim ever made in aluminium .
I've read about it, witnessed it and retensioned my wheel due to it.
I'd say this is basic physics also 😀
Slight digression - I am pretty sure that my back wheel spokes are doing much the same. They feel much looser than they should be, probably owing to me pounding my fat-ass around on them for a year, but they've only started to "feel" wrong recently.
They are aero spokes (3mm / 1mm section), which I've never trued before. The rim says "< 130kgf", so would there be any reason why the spoke type would reduce this at all or should I just aim for a sensible tension as I would on a normal wheel? These are an old-ish set of PX carbon wheels, and I've got no other data for them and they don't owe me enough to warrant a more practiced set of hands 🙂