Reasons for wheel failures

[bardygrub]

This thread was originally titled "Mavic Aksium" and due to popular request with the quality of information shared, it has been renamed and created as a "sticky".

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Hi All,

Had my 1st major service on my Cannondale a week and a half ago, got the skipping of the chain fixed and all of that is running fine. Before the service i had a slight buckle in the front wheel, which i reported and they trued the wheel. After about three rides i noticed the wheel was buckled again, checked the tension of each spoke and found one compleately loose.Have taken back to my LBS and have been told that they didn't think it would keep true from the last service and they are planning on using locktite to hold all the lugs in once they have trued the wheel.

Your thoughts?

Cheers

[Baalzamon]

Loctite on spokes I don't even want to know where that bike shop is.
A good wheel builder shouldn't have to worry about using a locking solution such as linseed oil, DT swiss spoke prep etc if they know how to build/true a wheel correctly. Sounds to me this shop has failed to back off tension when retruing hence spokes coming undone again.

[jules21]

mavic aksium is a rim btw - not the rim's fault.

[rkelsen]

Your thoughts?

Your tyre pressure is too high.

[JustJames]

mavic aksium is a rim btw - not the rim's fault.

Objection, your honour.

How is that relevant to the topic?

[greyhoundtom]

Your thoughts?

Your tyre pressure is too high.

? ? ? ? I'm sorry I just can't see that

[bardygrub]

mavic aksium is a rim btw - not the rim's fault.

Objection, your honour.

How is that relevant to the topic?

+1

[bardygrub]

Your thoughts?

Your tyre pressure is too high.

i ride them (AT) 120, so no its not to high!

[bardygrub]

Below is Mavic (Aus) responce. Quite a good reponce i think.

Hi Luke,



I’m sorry to hear this has happened to your front wheel. Our wheels are the best in the world, and we stand by that. But unfortunately, sometimes a wheel comes from the factory with a defect. All Mavic products carry a 2 year warranty against manufacturing defects, so given the age of your wheel, you’re well within your rights to take your front wheel back to West End and ask them to send it back to me for assessment if this happens again. It might have been incorrect tension from factory, it’s hard to tell without having the wheel in front of me.



Given your height, it’s not unusual for Loctite to be used on wheels. This doesn’t just apply to our wheels, this applies to any wheel. Tall riders place big loads on components such as frames, handlebars, cranks and wheels. There’s no avoiding it, but there’s nothing wrong with Loctite being used to stop the nipples from unwinding from the spokes. In fact, most custom wheelbuilders use Loctite on all their spokes, even for 32 or 36 spoke wheels, regardless of rider height.



I hope this information helps, let me know if you have any other questions.



Kind Regards,




Brent May | Technical Service Department Manager



Mavic | Look | Kona | EVOC | Straitline | Suunto | Pedro’s | Viva | Master Lock



O: 03 8878 1000

F: 03 8878 1001

[JustJames]

That is indeed a great response - supporting you, standing by the dealer and standing up for the product all at once.

Re: Loctite, I am just starting to learn about wheel building, so what follows is what I have read recently, not expertise that I pretend to have. Loctite is generally considered a second-best approach, but if it's good enough for Roger Musson, who is regarded as a wheel building deity, it's good enough for mere mortals at the LBS too. FWIW, Roger Musson uses Loctite 222 which is a removeable thread locker. Some flavours of Loctite, like herpes and possibly true love, are forever and should be avoided on your nipples. So there's another parallel with herpes.

[usernameforme]

that is a very good response... I just want to clarify is the rim is out of true (wobbles when you spin it) or if its buckled (bent).

[rkelsen]

Your tyre pressure is too high.

i ride them (AT) 120, so no its not to high!

That's arguable. IMO, anything more than 100 psi is too high. As a taller/heavier guy, I find 90psi to be the perfect balance for me.

Running lower pressures will ease the stresses on your equipment and prevent stuff like this from happening repeatedly. Why condemn yourself to constant equipment failure?

[bardygrub]

that is a very good response... I just want to clarify is the rim is out of true (wobbles when you spin it) or if its buckled (bent).

wobbles, when you spin it. well thats what it did do. its all good at the moment but i have only been on the indoor trainer. Tuesday will be the next big ride so we will see how it goes then.

[JustJames]

@rkelsen, how do you think higher tyre pushes lead to wheels buckling or going out of round?

[rkelsen]

@rkelsen, how do you think higher tyre pushes lead to wheels buckling or going out of round?

You might think I'm talking through my hat but I do speak from experience.

I had a set of the famously unbustable Fulcrum 7s which went out of true and started popping spokes within 1,000km. I had a hand-built set of wheels with 32 spokes and eyeletted rims which failed in the same way that the OP is describing (spokes coming loose)... only I had all 32 spokes in the rear wheel loosen to the point that the wheel was unridable within 25km of leaving the shop. The exact same thing happened to the replacement wheel they gave me. Then, the hefty 36 spoke wheels on a brand new commuting bike started busting spokes. They hadn't made it to 500km.

After having a whinge about all of this to my wife one night, she said to me, "you must be doing something wrong." That simple observation made me change a few things. Nothing else I tried had the same result as reducing the tyre pressures. Since dropping pressures 14 months ago (almost 10,000km), I've not had a single loose or broken spoke on any of my bikes. I bought a 2nd hand set of Fulcrum 7s for my road bike and they've been fine. Still running true, and they're yet to meet a spoke key. This is with 23mm Continentals at 90psi. My commuter runs 32mm tyres at 60psi, and it'll still be rolling on the same wheels long after I'm gone.

I'm not an engineer, so I can't explain the technical reasons for this with any certainty, but it makes sense to me that higher pressures would increase loads and stresses on the rim.

Note that my experience has only been at the bottom end of the market. I've never spent more than $300 on a set of wheels. I don't think you'd need to follow this advice if you're rockin' a set of Campy Eurus wheels. But for cheaper wheels, I'd say that it's worth a shot.

[JustJames]

@rkelsen, reading your post, what I saw is:

1. A bunch of wheels all made by the same wheel builder fell apart.
2. You dropped your tyre pressure when you went to a set of factory built wheels, and all has been well since.

Unless I am missing something, the change of wheel manufacturer was the cause of your change of luck. I know that worn rims can be blown apart by tyre pressure, but I don't see how high tyre pushes can lead to spokes coming undone. To the extent that higher tyre pressures push inwards on the rim, the rim is stable as a result of its round shape.

(Forum posts are a great way of losing nuance in communication - nothing to be read at anything other than face value.)

[rkelsen]

@rkelsen, reading your post, what I saw is:

1. A bunch of wheels all made by the same wheel builder fell apart.

Nope. Only 3 of the 8 wheels I've had problems with were built by the same guy. Unless he also secretly builds wheels for Fulcrum and Apollo... I haven't asked, but I doubt it.

Unless I am missing something, the change of wheel manufacturer was the cause of your change of luck.

If it were that simple, it wouldn't have taken me so long to figure out.

The rear wheel on my commuter now has only 11 of it's original 36 spokes. The others broke (individually) over a 6 month/3000km span. I replaced them as they went. Even with the 25 replacement spokes (and my amateur truing ability), I haven't busted any spokes since dropping the tyre pressure in June last year. And it gets ridden almost daily.

To the extent that higher tyre pressures push inwards on the rim, the rim is stable as a result of its round shape.

Cheap wheels made from lower grade alloys are a lot more flexible than you might think, which is why many manufacturers specify weight and pressure limits.

[The 2nd Womble]

I had 120PSI Ccontinental 18mm tyres on a set of Ambrosio's for 3 years with no problems. Had several other wheelsets with 23mm's (AT) 90-100PSI and had constant issues. Sometimes wheels simply suck.

[toolonglegs]

My Aksium lasted about 1000kms before it totally destroyed itself... Cracks on every spoke hole... Not the greatest wheel for a big guy. But this was 2006 so they may have improved.
I like Mavic wheels ( live 10 km's from the factory )... But I never keep them after the 2 year warranty is up!.

[DW260]

I've had Aksum's and ksyrium elites. Both front wheels have needed rebuilding within 300km's with loctite. I weigh in about 90kg and run anywhere between 100-120psi.

Never had any further dramas beyond them going out of true but once rebuilt have been fantastic. I put it down to mass production and bedding components in.

[AndrewBurns]

My aksiums have gone over 2500km no problems so far, I did notice some slightly rotated spokes a few hundred km ago directly after I hit a pothole hard enough to get a pinch flat but I've not had any problems and they're still true. I'm not a heavy guy but I don't really avoid riding them over bad surfaces, I think that like with all other wheels your weight has a huge impact (and at 64kg most wheels are designed to last under somebody twice my weight which makes them indestructible under me).

[grnis200]

My Akums have 30,000kms, 3 Melburn Roobaixs and lots on CX riding and are still true.

I ride 25mm at about 90psi, weigh in the low 70s and ride light over rough stuff.

[Reman]

The Mavic's are factory built, yes? This inherently lends itself to a good level of quality for most items but what you will get is an outlier or two per 1,000-10,000 wheels built. On forums you tend to hear of the outliers.

As for loctite on nipples, it's a bandaid for a wheel that has been with minimum standards (though they may be high minimum standards) rather than a wheel built to maximum standards (usually hand builts, usually).

How many of you have greased a fastener on your bike, fastened to the correct torque and then found it came undone?

I built 32 spoke 3 cross wheels and all my spokes and nipples are greased (no loctite or linseed oil). I have had one rear NDS spoke unwind, but I probably didn't tension it enough in the first place, my mistake. After a few 100kms they are as true as the day I put them on, to my ears and fingers the tension in the spokes hasn't dropped and I'm confident they will stay that way.

[ironhanglider]

I'll chime in with some wheel building theory. Note that I am not any form of engineer or describe myself as an expert, I have merely read some of the books and read some forums like rec.bicycles.tech for a long time where people like Jobst Brandt and Sheldon Brown would contribute. I have also built many wheels for myself, family, friends and customers (when I worked in various bike shops) and have found the following points to hold true.

- Spokes lose tension temporarily when they reach the bottom of the wheel when they are being ridden.
- The fewer spokes there are the more tension each spoke will lose at the bottom
- The more flexible the rim is the more tension each spoke lose at the bottom, lighter and shallower rims tend to be more flexible
- Higher tyre pressure will reduce the tension in all the spokes
- Higher loads (weight) will reduce the tension in the spokes at the bottom
- Pedalling action will reduce the tension in the 'pushing' spokes
- Impacts will reduce the tension (presumably at the bottom).
- Spokes that lose all tension cause problems such as the nipples unwinding and the spoke fatiguing and failing particularly at the elbow (and less commonly at the start of the threads)
- Nipples unwinding can be solved by thread lockers such as loctite, linseed oil etc, or by increasing the tension in the spokes
- Fatigue failures can be dramatically reduced by stress relieving the spokes but for some reason many wheel builders don't do this and few factory build wheels are
- Highly tensioned spokes tend to result in wheels that are less prone to require re-truing.
- Wheels built with highly tensioned spokes are more likely to have fatigue failures in the form of cracking around the spoke holes.
- Wheels built with highly tensioned spokes are more prone to 'potato chip' failures
- Spokes are almost never broken from too much tension.

As you can see some of these factors will combine together this explains why the most common spoke breakage is at the elbow of a pushing spoke. But the weight the wheel carries is almost certainly the largest factor. This explains why the most powerful sprinters still use low spoke count wheels, whereas 40 and 48 spoke wheels are common on touring bikes and tandems. Historically many bikes (British at least) were built with 40 spoke rear and 32 spoke front wheels to reflect the different loads. Somewhere along the way someone figured out that it was cheaper to use the same drillings for the rims and suddenly 36 spoke F&R wheels were standard even for high performance wheels. Then someone got the idea that fewer spokes were lighter and that most high performance wheels were used by people who could get away with 32 spokes. This was in the days of low profile sub 300g rims. Then came the deeper section rims, I suspect more for strength than anything else but they were also marketed as being more aero. This allowed builders to use fewer spokes again but come with a weight penalty. Sheldon said that having the same spoking F&R means that you either have a front wheel that is unnecessarily strong (and therefore heavy) or you have a rear that is not strong enough.

Velocity Deep Vs are renowned as being strong rims, but they weigh in a 520g or so. If I were to build a set of wheels with these I could probably get away with 24R, 20F spoking even though I weigh 110kg at the moment Although I'm not particularly hard on wheels. In fact my race wheels have carbon rims that are lighter but deeper than this.

My Aksium lasted about 1000kms before it totally destroyed itself... Cracks on every spoke hole... Not the greatest wheel for a big guy. But this was 2006 so they may have improved.
I like Mavic wheels ( live 10 km's from the factory )... But I never keep them after the 2 year warranty is up!.

If I were to build a set of wheels for TLL for example they would end up being heavier and have more spokes than he would choose to use so it is no surprise that he goes through wheels at a steady rate. The next best solution would be to tension them up higher and hope that he breaks them through some non-warranty mis-adventure before the rims cracked through fatigue.

Before the service i had a slight buckle in the front wheel, which i reported and they trued the wheel. After about three rides i noticed the wheel was buckled again, checked the tension of each spoke and found one compleately loose.

Wheels that have low spoke counts are more susceptible to having the nipples unscrew due to the de-tensioning at the bottom of the wheel. Once this process starts a spoke loses even more tension which is what bardygrub found. The solution is either a threadlocker to stop it unscrewing, or more tension overall. (or wheels that have either more spokes or heavier rims)

Your tyre pressure is too high.

Increased tyre pressure does contribute to the unscrewing of the nipples by reducing the tension in the wheel overall, and possibly also by not letting the tyre cushion impacts as well. Some of rkelsen's other wheel woes sound also sound like either a lack of tension and a failure to stress relieve the spokes, the tyre pressure contributed to the lower tension. The commuter wheel also sounds as if it was afflicted by a bad batch of spokes. Shogun Metro SE's were famous for this in the early 90's and Sapim had trouble with a batch recently (2007?) too.

Part of wheelbuilding is science and you can plug in the numbers and say that for a given weight and rim you need x number of spokes in each wheel at x tension, part if it is art because some riders are just harder on wheels than others of similar weight/height/power. It is easy to overbuild wheels to make them reliable, but to put 48 spoke Deep Vs under a 45kg climber will not give them good performance. This is where the good builders (like TWE) really add value to extract maximum performance at adequate strength/reliability.

Thanks for reading such a long diatribe.

Cheers,

Cameron

[toolonglegs]

The only reason I bought an Aksium was I was OS at the time and had destroyed a rear wheel ( miserably at the top of a 45km descent )... So I needed a cheapie.
I have had wheels built to last... And they have but the hubs have died instead. Of the wheels I have destroyed 50% have been from hub / axle failures... And new wheels are cheaper than replacement parts quite often.
The next wheels I will build will have spoke count limited by the available rims... ie: there isn't a lot of choice in tubular alloy rims.
Everything is a compromise.
Nice post btw.