GravelMN

A while back I posted a question about a rear wheel that developed a bad habit of loosening spokes. The wheel had about 3,000 trouble-free miles on it when it started giving me trouble this spring.

At first I thought the spokes were loosening at random and I detensioned, inspected everything, and retrued/tensioned a couple of times with no improvement. I replaced all the nipples, cleaned the threads and applied Rock n Roll Nipple Cream. The problem didn't go completely away, but only one or both of the spokes adjacent to the weld were loosening. All other spokes stayed in tension.

Out of frustration, I replaced first the leading, then the trailing spoke that straddled the weld, again using the Nipple Cream. The problem persists though it takes more miles for a spoke to loosen, but it is always one or both of the spokes straddling the weld. No cracks, eyelets look fine inside and out, nipples have backed off enough to show threads.

What would cause the NDS spokes on either side of the weld to become problem children after 3,000 miles of riding?

• Mavic 2012 Open Pro
• 36h laced 4X
• DTSwiss Comp 2.0-1.8-2.0 spokes
• Brass Nipples
• 105 hub
• 105 kgf DS
• 55-70 kgf NDS
• Precautions taken to prevent and relieve spoke wind-up

prathmann

In general the cause of spokes loosening is that they lose tension when they are at the bottom of the wheel. Once tension is lost (or at least very low) any vibration can cause the nipple to turn and loosen the spoke further. The NDS spokes are under less tension, so they are most likely to become almost slack when at the bottom of the wheel rotation. I'd guess that your rim is just a little more flexible near the weld so the rim deforms a little more at that point when at the bottom so NDS spokes near the weld are the ones that lose the most tension and are then prone to loosening.

Hard to say why it took 3000 miles. When wheels are built the spokes are frequently treated with some kind of weak thread locker such as linseed oil. This could have been enough to keep the nipples from turning but may now have worn off or been pushed out of the threads due to vibration over time. You might want to try a stronger thread locker if you don't want to go to higher tension.

GravelMN

I built these wheels myself. I originally used just a bit of anti-seize (which I've used on numerous other builds with no problems). Now, even after replacing all the nipples (cleaning the spoke threads with mineral spirits and drying) and the two offending spokes, and using R&R Nipple Cream, the two NDS spokes crossing the weld still have a problem. I probably shouldn't go higher tension as Mavic recommends 95 kgf and I'm already at 105-110. My wheel-building mentor told me he never goes over 115 kgf even on a double wall, double eyelet rim like the Open Pro.

I did have a couple of flats on rough roads on this rim earlier in the season. I have inspected the weld and the eyelets (inside and out) several times using a bright light and could not see any signs of cracking or displacement but I'm starting to wonder if there is the potential for hidden damage at the weld joint that is allowing it to flex more which is causing the problem. I contacted Mavic but have not yet received an answer.

clasher

Why did you choose four cross? I've built a few wheels like yours but never gone more than three cross since the spokes cross over the heads. One of my wheels has about 10,000km on it and no issues.

fietsbob

4 cross , you wont pull a spoke hole out , radial it's more possible..

48 hole 5 cross same thing..

3alarmer 

...I, too, think these are your alternatives. the only other possibility I can think of is that your spoke tensions are very uneven from spoke to spoke, and that seems not to be the case from your description.

...I honestly don't know why people have this idea about tensioning. If you are a heavier rider (like me, for example) the downward force that pushes on your wheels is considerably greater than some lighter person like my friend Amanda, who weighs maybe 120 pounds soaking wet. So wheels I built for her were less of a problem in the final tensioning process, because of this.

Additionally, you get into the whole "less spokes is better because more aero" thing, and the only rational solution to fewer spokes in a tensioned bike wheel is higher tension per spoke. It's just the way it is.

Unless and until I start to get distortion in the rim in a set of wheels I build for hauling my 240 pound ass around the town, I pull them up pretty tight at the end...and I'm sure I probably exceed manufacturer's recommendations on many occasions. And I'm always in the 32/36 spoke range for spoke count. On a rear wheel, the only way I can get what I consider to be high enough tensions on the long side (non drive spokes) is to go up into the 120-125 kgf range on the drive side.

I use eyelet reinforced rims for this reason, and I guess my feeling is that I'd rather take the chance on some remote possibility of cracking there in the far future than have the spokes constantly flexing and failing due to low tensions on the non drive side of the wheel.

Anyway, that's what I do. You should ask your wheel guru why he feels that way....maybe he has a convincing reason for it.

GravelMN

I chose 4X as these are wheels for endurance rides of 100 miles or more with a 230# rider. The longer spokes and greater tangent make them able to absorb more fine road vibration without having to go up in tire size. My current frame barely fits 28mm tires and I ride 25mm for decent mud/debris clearance.

His logic is that, unless you have rims specifically designed for higher tensions, running too much over the manufacturer's recommendations increases the risk of cracking at the spoke holes (I lost a Salsa Delgato eyeletted rim this way at about 125 kgf within 500 miles) and running too close to the point where the rim will taco increases the chances of catastophic failure if you have an impact like a curb or large pothole or hard landing from a bunny hop over an obstacle.

.

dim

read the title of the thread and am dissapointed .... was hoping for something more 'erotic'

3alarmer 

...I'll take your word for it on that Salsa rim. It's not something I've personally experienced. The catastrophic failure thing is an interesting take, one I've not heard before, and not something that would be an issue for me. Hitting a curb is gonna be painful whatever my spoke tensions.

FBinNY 

Since the problem is isolated to two spokes and nipples, I suggest dealing with it with a focused approach.

I NEVER lock nipples to the spokes, but if the OP cleans the nipple head and eyelet he can use a post-assembly thread locker, or wicking adhesive to lock the nipple to the rim. That bond will be relatively weak and not make truing impossible or difficult later.

If it were mine, I'd try my luck with a belleville washer or split lock washer to increase the spring range keeping the nipple under load. There are also "twisted star" (don't know the exact name) lock washers designed to work like ratchets ramping when tightening, biting to prevent loosening.

FWIW - the OP can discount concerns the number of crosses, since that's not related to the problem.

GravelMN

FBNY

Thanks. I hadn't considered a lock washer to help keep the spoke under tension. As for a post-assembly thread locker, do you have any recommendations for product or brand? I considered using the low strength Lock-Tite brand during assembly but wasn't sure that was appropriate.

Still haven't figured out why this started so far into this wheel's lifespan but multiple close inspections under bright light from various angles and feel with finger and a fine point have failed to reveal any cracks on the inside or outside welds and there is no displacement with detensioning or retentioning.

3alarmer

The Salsa Delgato rim was warrantied but the model came off the market shortly thereafter, supposedly for warranty issues according to my LBS, so that may or may not have had anything to do with the failure, but it developed very obvious cracks around most of the DS nipples. That wheel was built by my LBS with the tech teaching me as it was built. It is the only wheel I have ever had fail in this manner, but also the only wheel with the DS spokes over about 115 kgf.

When I contacted Mavic about the Open Pro, all they would say is that the recommended tension was 95 kgf and that some builders go higher, but that is at their own risk. The wheel-builder who taught me the most (not the same guy who built the Salsa-rimmed wheel) told me that going with tensions very close to the point of rim failure puts you at risk of a rim taco if an impact or other severe stress pushes the rim past that limit. Keeping the tension a reasonable margin from the the failure point, gives you a buffer. The word "catastophic" for tacoing was my word, not his.

3alarmer 

...I have used the Loctite green threadlocker with some positive results in cases like the one you describe. The issue you run into is that no threadlocker will work as designed if there is already grease, oil, or anti-seize on the thread interface surfaces. They are mostly formulated for clean surfaces.

CoRide59

I think this is the key. Its only the weld spanning spokes and didn't do it from new, and at 230# your not the lightest guy to ride a bike. I agree that the rim is flexing at this point and allowing the NDS spokes to loosen. My thought though is that there has to be a reason, and thread lockers and lock washers are just going to be band-aid's hiding the real issue. You may not be able to see any cracks, but the rim has weakened in the weld area. I say its time to replace the rim, the weak area is going to continue to flex and continue to weaken. The band-aid's will just allow you to continue to use the wheel up to the point of a much worse failure.

3alarmer 

...I think maybe your guy is wrong on this. Read from about page 28 on through about page 35. Actually, the whole book is a good read. A lot of us ancient guys learned about wheels from this book.

FBinNY 

If you had gone to the Loctite site and looked at the user guide, you'd have found the application on Page 3.

It's kind of small print, so to help, it's T-290

xenologer

Use a Rim Flat Spot Puller
to deform the rim outwards at the location of the loosening spokes
so that the problem spokes will be under higher tension after truing

GravelMN

On page 105 at the end of the first and beginning of the second paragraphs under final tensioning, I believe he describes the condition of tensioning to near failure when he describes the maximum safe tension as one half turn under the point where you get rim distortion during stress relieving and states that a strong, safe wheel should be able to handle about 10% overload without damage. My mentor told me that leaving a wheel too close to failure tension could result in failure (taco) during high loads. This section by Brandt seems to concur that you have to back off to leave a 10% buffer to be safe.

FBinNY

I was aware of Loctite 290 but not certain if it had appropriately light holding strength for this application. I'm also aware that there are other thread lockers on the market besides Loctite. Thank you for your recommendation.

CoRide 59

That is what I'm starting to feel is true. Something has changed and it's time to consider replacing the rim (or even building a new set of wheels, which I like doing anyway). Sounds like a good winter project. Maybe my other winter project is going to be losing 25-30#.

FBinNY 

Keep in mind that you're to use it between the nipple and rim, not on the threads.

3alarmer 

...yes. That's a 10% buffer on a wheel, and it varies with the individual rims being used. And the only way to determine it for different rims is to slowly and carefully take the spoke tensions up until the rim begins to distort, and then back off.

He's not talking about manufacturer's recommended maximums, he's talking about how tight you ought to tension a wheel, and it is a variable depending on the rim you use...........which you figure out yourself. IOW, pull them up pretty darn tight. Like I said, start reading on about page 28, try to understand all the things going on in a rear wheel. Or go with what your guy told you...it makes no difference to me, other than I think he's probably wrong.

Loose is more likely to result in failure than tight, for several reasons.

79pmooney

What is the tension of the two problem spokes? Rims frequently have hops at the weld. I often find myself juggling between tighter than I like vs living with the hop. I can imagine a manufacturer figuring out a way to minimize the hop, perhaps by welding sequence. If that were the case, it might be possible to overdo it and have a flat spot there. Then a roundness truing would leave those two spokes loose instead of tight. Those loose spokes could go to zero tension say on hard bumps when they are down. Around 3000 miles, this has happened enough that they have loosened to the point of regularly going slack.

This is pure speculation. But knowing the tensions on those two spokes vs the rest could tell you a lot. Tell us what you find.

Ben

79pmooney

4X 36 hole wheels go a long ways. The spokes crossing the heads is a complete non-issue. I get great results with both low flange hubs and high. Even the very high Campy Tipo hubs. I was doing this for years, never paying any attention to the spoke heads and getting great results when people started telling me of all the problems that happen from the spoke/head interference. Hasn't changed either my wheel building or my experience.

I no longer build many 4X wheels but that is only because 32 spokes has become the new standard. My old wheels that are still going I rebuild 4X (and often just replace the rims and reuse the spokes). 17,000 miles was the most I have ever recorded on a 4X wheel, but my winter wheels go three rims on a set of spokes. (That 17,000 mile rear wheel failed bunny-hopping a pothole. No sidewall left.)

Ben

Bike Gremlin

This is incorrect. Spoke length does not give noticeable comfort increase. Tyre contributes to that with about 99%. 4x is just as high as cross number goes on a 36 spoked wheel. Make sure the nipples don't bent the spoke too much.

"Since tire elasticity is about one hundred times greater than spoke elasticity, the
elastic differences between the shortest and longest spokes used in different
spoke patterns amounts to less than 0.1%
Because the swaged portion of
commonly used spokes of different lengths are mostly the same length, length
differences among these spokes have even less effect than those of straight gauge
spokes."
- Jobst Brandt - Bicycle Wheel
- A book I'd highly recommend reading before building your wheels.


I'd go with 3x for 36 spokes, even though 4x is doable.

Spokes becoming loose sounds like too little tension, or twisted spokes.

When tightening the spokes, overdo it by 1/4 of the turn, than go back for the same amount. That should help eliminate spoke twisting.

GravelMN

3alarmer

Agreed, I was using 115 kfg as a reference point, not the manufacturer's recommendation of 95 kfg. I'm not arguing with Brandt at all, just acknowledging that there is a point where the tension is so close to the failure point that the wheel could fail under stress, thus the recommended tension of 10% or so under the failure point.

79pmooney

The spokes in question are brought within the same range as the other spokes on the NDS each time I have trued and tensioned. This leaves about a 1mm (flat) hop over the weld which I have never been able to completely eliminate and which doesn't bother me at all.

I also have 36h 4X on my MTB and touring mutt that have never had any problems. They get used on rougher roads/trails but don't have nearly the miles on them that my road bike has.

Slaninar

I was told by a reputable wheel builder that 4X decreased road vibration not as much due to spoke length as to increased tangent with radial spokes creating the roughest riding wheel and 4X the one that transmits the least vibration, all other elements being equal. Agreed that tires make significantly more difference than the spoke pattern but as I mentioned earlier, my road bike will barely fit 28mm tires (no clearance for mud or debris) and I usually ride fairly supple 25mm tires (Bontrager AW3).

I have Brandt's book and it is always a great help and I destress my wheels several times during tensioning and I always make the last turn slightly counterclockwise (as if looking at the nipple end through the rim).

Thanks everybody for the input. I appreciate it. As I mentioned, I have built several sets of wheels and did my own truing, tensioning, and a few spoke or rim replacements for quite some time before that. As it was built in the same manner as the other wheelsets I've built, held up with no problem for over two years, and I've gone over it with a fine-tooth comb several times, I'm relatively confident that this a new-onset problem specific to this wheel, not a mistake during the original build. While I may continue to play with it as a learning experience, I will probably try replacing the rim or use it as an excuse to build another set.

trailangel

All this tension talk.. measured with tire off or tire on inflated to riding pressure?

FBinNY 

Any published tension spec would be without the tire mounted.

The two reasons are that spec are w/o tire are because one with tire mounted and inflated would;


1- call for the builder to mount tires to check his work
2- call for information not available, namely the tire width and pressure

Specs have to deal with known facts, and not be based on assumptions about what may follow. In Legal documents they refer to the "Four Corners Rule", namely that everything needed to interpret the document is contained within it's four corners. The same basic philosophy applies to specs.


Now, the above refers to published specs from authoritative sources. What people posting on forums may mean is something else entirely and all bets are off.