Mavic X138 rim crack

[fastpedaller]

confirms my decision to choose a different rim manufacturer. Don't however, underestimate the wheelbuilder's part in it all.

I've been building wheels (for myself and others) for over 30 years. I stick with Mavic. It could be the OP's issue is the spokes being too loose?
Some would think that statement is the opposite to the case. The logic is that the tighter the spoke are, the more they 'share' the loadings. Think of it as all the spokes being absolutely slack - if you sat on the bike only the one spoke from hub up to rim would take a load (ok the rim would deform terrible as well - but you get the point?). So maybe this was a machine built wheel, and too loose causing stresses in use to damage the rim?

[mercalia]

no though this was/is a machine built wheel the spokes on the drive side atleast are tight - cannt be any tighter. The ones on the non drive side not so tight but then these are non butted same on both sides. I wonder if maybe too tight on the drive side. The wheels have taken a bit of battering lately. But does alloy go soft or brittle as it gets older - this wheels hail form 1999 I think orginal to the 1-Down. The wheels are still true inspite of this all.

[fastpedaller]

Yes- aluminium alloys work harden, so it could be the effects of that, maybe the alloy wasn't quite within spec at manufacture? Only something I've seen happen once before.

[531colin]

Isn't it anodised Mavic rims that are known for this type of failure?
And what was the rim (fitted to Ridgeback, amongst others) that was known for it? Been on the forum, and I can't find it, needs somebody who knows how to search
edit... found...http://forum.ctc.org.uk/viewtopic.php?f=5&t=40617&hilit=alex+dh19&start=30

[Brucey]

I think that rim is anodised; it is just silver anodised. It is also a single eyelet rim, with a stainless eyelet. Add stress and a splash of salt water and cracking is almost inevitable, I'd have said.

I've seen lots of cracked Mavic rims, some with double eyelets, most without, mostly rear rims rather than fronts.

However I don't think they crack very much more than lots of other rims, and for the weight they are, somewhat less than many others.

Rims are arguably either consumables, or somewhat heavier than they need to be.

cheers

[531colin]

That was my point, really....a light, anodised, single eyelet rim is an interesting choice for an on/off road load-lugging tourer....isn't it?

[Brucey]

I think that mavic rims help to sell bikes and that the x138 is a cheap rim that makes a bike fitted with it seem a bit better and a bit lighter than it really is. Actually I think they are usually OK in unladen front use but not for rears or laden work, so yes, an odd choice like you say...

(when the rim breaks, what do you say? -'one down and one to go...?'.... )


cheers

[mercalia]

Brucey
"when the rim breaks, what do you say? -'one down and one to go...?'..."

I hope thats not the original meaning of the Dawes 1-Down?

[mercalia]

well I got my new wheel a Ryde Sputnik made in Europe it seems. It has some safety red arrows maked on the sticker - what are these?

click to zoom in

[531colin]

It wears through into the "little ears" in the channel......



http://www.ryde.nl/en/products?product=24

[mercalia]

My new wheel, the Sputnik was built by a Sam Garside of Spa Cycles - seems very nicely made & seems to ride much better ( could be 559x19 rather than 559x17) He said that they had been having trouble with the silver sputniks with a bad batch- that they couldnt take the tension and have to send them back - the reason why I got the black one was older stock, he had tried with 3 silver ones and no good. Nice to know some one has pride in his work that he will put his name to it and will only send out work of standard to be judged by?

[NATURAL ANKLING]

Hi,

That was my point, really....a light, anodised, single eyelet rim is an interesting choice for an on/off road load-lugging tourer....isn't it?

Is'nt a single eyelet rim wall thickness (box construction) where the eyelet is, thin compared with a single eyelet non box section rim ( very cheap single wall steel spokes an all ) so its the thin wall that is the problem

Both single and double rivet rims use same rims

I just had a gander at a mavic single rivet rim (split brake face) and compared to a very cheap non box single wall construction single rivet rim its only half as thick.
Not a very good advert for a brand name rim, silly compromise I think.

[mercalia]

Is'nt a single eyelet rim wall thickness (box construction) where the eyelet is, thin compared with a single eyelet non box section rim ( very cheap single wall steel spokes an all ) so its the thin wall that is the problem

I just had a gander at a mavic single rivet rim (split brake face) and compared to a very cheap non box single wall construction single rivet rim its only half as thick.
Not a very good advert for a brand name rim, silly compromise I think.

Yes I used to have Dawes Horizon Tour - a cheapo version of the Galaxy, good frame cheap bits incl the wheels. The wheels were single wall and I never had any trouble with cracks - and that bike was used for years on a variety of terrain ( until some toe-rag tried to steal it and when they couldnt, smashed the frame out of anger ) Its a shame that cant get more single wall rims - they used to be ok for most people?

I see that Mavic still have a rim similar to the X138 in their line - the Mavic XM 317 ? box section single eyelet - they never learn it seems.

[Brucey]

single walled rims served us well for many years but when push comes to shove they don't resist some of the service loads as well as rims with larger hollow sections and a double-wall in them. If you look at the evolution of aluminium rim design it went from single-walled to shallow double walled to deep section double walled. In all variants there are ones with and without eyelets (double or single for double walled rims). Personally I would have been happy to have stopped with shallow double-walled rims for touring bikes, but we are where we are.

Modern double-walled rims are much stiffer than older shallower designs. This at first appears to be nothing but a good thing until you look further into it. Less stiff rims fail by Euler buckling if they see too high a tension, but modern designs don't. IIRC Colin may have previously reported that he has tried and failed to cause a modern rim to fail in this way. The problem is that the spoke tension can be too high in some of these rims anyway; the 'new limit' becomes the static stress at which cracking will occur. It has been my observation that in many cases the cracking is environmentally assisted, but it happens anyway if the spoke tension is too high.

Mavic (like most manufacturers) publish specifications for the maximum spoke tension. These values are widely ignored, and this in large part is why so many rims crack. Some (a few at least) will crack at lower tensions anyway, but most are overtensioned.

In the case of Mercalia's wheel I don't think it was a good choice of rim for that application. However I would also bet money that the DS spoke tension was way too high to start with. My personal view is that Mavic's tension recommendation is pretty much impossible to adhere to if you are building a 130mm 8/9/10s rear wheel with PG 14G spokes, unless you use thread lock on the spokes. Even with pretty stretchy DB spokes, and a 135mm hub the wheel will tend to slacken off on the NDS in moderate to hard use unless threadlock is used.

cheers

[NATURAL ANKLING]

Hi,
What I ws trying to say was that if like me you used unfashionable cheap unbranded single wall non eyeleted steel spoke rims like what I pull from skip bikes these are pretty reliable and very strong, the rim wall at spoke it quite thick.
OK these are MTB rims so more symetrical dish etc.

Bad design to use a box construction rim and expect that the thin single wall will survive, thgough that was not my experience with a mavic box construction single eyelet, MTB again

I have had my second broken spoke in over 40 years of cycling over all surfaces on all quality rims.
One on a rebuilt wheel 700x21 x 135 box section double eyelet new rim new nipples but old hub and spokes (single butted / plain ? thick spoke)
Several attempts and pulling my hair out with lose spokes Then a broken NDS spoke on a long ride at nipple Had spare spokes on the chain stay
I had to lube the threads to dismantle wheel and then degreased threads before rebuild, just cant get the spokes to stay tight

Second break was a redished 130 to 135 MTB single wall steel spokes non eyelet drive side on the skip trainer, siezed spokes prior to redish so no surprise there.
Sorry if off topic, needs a new post really.

So what do you do with constantly loosening spokes
I am have considered thread lock several times.

Like 531colin says as a pro wheel builder you have to build so that you can send them out to all and sundry and they will be reliable, I am just a diy fidler.