Mavic X138 rim crack

For discussions about bikes and equipment.
mercalia
Posts: 11107
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Mavic X138 rim crack

Postby mercalia » 1 Oct 2014, 11:35am

Brucey wrote:.....

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



well I have no way of knowing what the tension on the DS is but it dont seem much different from my new Sputnik. The NDS
I was always worried about seemed slack, but then it uses plane gauge spokes all round. I dont know how long the cracks have been there but recent going over the paths on NR1 from Gravesend and round about didnt do it much good plus my weight of 17- stones. I think had it had double eyelets then this cracking wouldnt have happened as the internal wall fine; I cant see any point in single eyelets unless you are a racer? Are double eyelets a large cost difference? I was always worried at spoke breaking - I did have 2 break 1100 miles ago but nothing since. So upset at having to bin this wheel - the hub fine, the spokes fine just a crap rim & the only rim I can replace it with is another Mavic single eyelet rim with ERD 544 - no point in doing that.

Brucey
Posts: 35228
Joined: 4 Jan 2012, 6:25pm

Re: Mavic X138 rim crack

Postby Brucey » 1 Oct 2014, 3:12pm

IIRC a sputnik will take a higher spoke tension than your old rim.

BTW double-walled rims can crack too; but when the external wall cracks the rim is usually still OK to ride on for a while because the second eyelet shares the load. Often the second eyelet doesn't take much load until the out wall cracks, which is why the outer wall cracks...

If you want to re-rim your old wheel then think about a Rigida ZAC19 rim. 542mm ERD (IIRC) ought to work with your old spokes unless they are already a bit too long?

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
531colin
Posts: 12468
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Mavic X138 rim crack

Postby 531colin » 1 Oct 2014, 7:06pm

I typed this before going for a ride this morning....the thread has moved on a bit, but I'm posting anyway......can't say I had a premonition about NA's spokes loosening.

I have never managed to pretzel a Sputnik....they are wide, deep, box section rims of impressive rigidity.
Sputnik are pretty weighty to start with, and a single-wall rim of similar width could use a very thick wall without a weight penalty.....however, it would necessarily be less stiff, and flex more in use, so you would get greater variation in spoke tension each revolution, more spokes slackening with use, and faster spoke fatigue, as well as more susceptibility to accidental damage.
Its quite easy to pretzel a Chrina during building, and a single-wall rim of similar width would be impossible to build 130mm OLN, 9speed, with acceptable tensions on spokes both sides.....either the left spokes are slack enough to come loose in use, or the right spokes are tight enough to pretzel the rim. That's my recollection of the early 6 and 7 speeds, before the OLN increased....I only remember one early, deep section, single-wall rim, Constrictor Asp, and I wasn't that impressed....on mine, the spokes fatigued at the nipple thread, and I wrote them off on a pothole in the dark at the beginning of a 24 hour reliability trial....I probably weighed under 10 stone at the time.

User avatar
531colin
Posts: 12468
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Mavic X138 rim crack

Postby 531colin » 1 Oct 2014, 7:16pm

I'm not sure these double eyelets are much more than smoke and mirrors. OK the inner bit of the double eyelet (the "bellwasher") acts as a nice big washer to spread the load on the hub-facing wall of the rim. But they aren't that accurately installed in many rims....for example, you can get a feeler between the bellwasher flange and the tyre-facing wall of the rim, so there isn't much load-sharing going on until the hub-facing wall fails, as Brucey says.

Of course, if the end users would accept heavier wheels, or fewer gears or an assymetric frame for less wheel dish, none of this would be a problem.... :wink:

mercalia
Posts: 11107
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Mavic X138 rim crack

Postby mercalia » 2 Oct 2014, 12:54pm

Brucey wrote:
If you want to re-rim your old wheel then think about a Rigida ZAC19 rim. 542mm ERD (IIRC) ought to work with your old spokes unless they are already a bit too long?

cheers

Yes thats looks like a good rim and 100grm heavier. The spokes on my wheel are level with the end end of the nipples so a few mm can show thru if necesssary

Thanks for the info but I knew there would be a catch lol- seems like not easy to get hold of here in the UK SJS dont stock the 36 hole & their distributor dont have any; google dont throw up any here in the UK - will have to get one imported & there is the added problem that there is a Single eyelet and double eyelet version to be wary of. But I think will be worth searching out as I would like to try my hand at wheel building and if it goes worng then it dont matter as I have a good wheel in the Spa Sputnik. thanks for the info

mig
Posts: 2032
Joined: 19 Oct 2011, 9:39pm

Re: Mavic X138 rim crack

Postby mig » 2 Oct 2014, 12:59pm

http://www.hilarystone.com/rims700.html

at the bottom of this page. same zac19 rim??

mercalia
Posts: 11107
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Mavic X138 rim crack

Postby mercalia » 2 Oct 2014, 1:09pm

mig wrote:http://www.hilarystone.com/rims700.html

at the bottom of this page. same zac19 rim??


I need 26" but will look and see if they have that also

no seems not. thanks for your time to look for me

i need 559x 19 36 spokes and double eyelet

AH found a place in Germany if any one else is interested -

http://www.starbike.com/en/

even with postage which is high is not too bad. seems like they are v cheap in Germany. 13 euros/£10 or so!

mercalia
Posts: 11107
Joined: 22 Sep 2013, 10:03pm
Location: london South

Re: Mavic X138 rim crack

Postby mercalia » 2 Oct 2014, 10:29pm

ah I found this old post about these rims lol

http://www.thorncycles.co.uk/forums/index.php?topic=4751.0

User avatar
Sweep
Posts: 5514
Joined: 20 Oct 2011, 4:57pm
Location: London

Re: Mavic X138 rim crack

Postby Sweep » 5 Sep 2019, 12:03pm

Not the same rim but thought I would add this to the library of cracks (found this thread when searching for info).

Mavic CXP22 (one of the old ones with more metal I gather than the "elite") 32 hole. Rear wheel.

Heard a strange clicking sound riding back from town (London), assumed it was a mudguard catching or something - on checking the mudguard, did find an issue, but then found these.

IMG_20190830_132848817.jpg
IMG_20190830_132802346.jpg


The braking surface still has plenty of wear left so a bit peeved.

Bike not usually too heavily loaded (It only has a tubus fly rack) but am wondering if I may have brought this on by my recent adoption of this bike for shopping trips with two big panniers on the back. They would be taking a fair bit of weight.

Will limit my shopping trips to my sputnik wheeled bikes in future I think.

If anyone wants a pic of the bike to help judge, just ask.
Sweep

Samuel D
Posts: 2803
Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: Mavic X138 rim crack

Postby Samuel D » 5 Sep 2019, 12:11pm

Do you know what the spoke tension was and whether the spokes are swaged? Shopping adds to the cyclical load on each spoke regardless.

pwa
Posts: 10075
Joined: 2 Oct 2011, 8:55pm

Re: Mavic CXP22 rim crack

Postby pwa » 5 Sep 2019, 12:12pm

32 spokes? That is a tad low on spokes for heavy panniers. But even so, this sort of breakage isn't normal. Maybe the rims were faulty. This sort of failure put a lot of people off Mavic rims. Or maybe the spoke tension was excessive.

Brucey
Posts: 35228
Joined: 4 Jan 2012, 6:25pm

Re: Mavic X138 rim crack

Postby Brucey » 5 Sep 2019, 12:24pm

CXP 22 are pretty good rims but (like most rims of this sort of weight) all you need is

- a heavily dished rear wheel
- too much tension in the DS spokes (BTW most wheels are built with too much tension vs Mavic's recommendations)
- salty water added
- no corrosion protection
- service loading

and cracks will result.

FWIW the least important element is service (fatigue) loading. If it were then you would see cracks in NDS spoke drillings too; they see slightly larger fatigue loads if anything. As it is you can go for a winter's ride, park the bike up and come back to it a few weeks later with cracked rims; that is stress-corrosion cracking for you.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
Sweep
Posts: 5514
Joined: 20 Oct 2011, 4:57pm
Location: London

Re: Mavic X138 rim crack

Postby Sweep » 5 Sep 2019, 1:06pm

Samuel D wrote:Do you know what the spoke tension was and whether the spokes are swaged? Shopping adds to the cyclical load on each spoke regardless.


No idea to be honest.

I have had the wheels a few years.

Will not use such wheels again for shopping - I have other bikes I can easily use.

and, on the positive side, the experience will encourage me to start wheel building/rimming.

(the bike by the way is the one pictured in my very recent thread start on different rims front and rear)
Sweep

Brucey
Posts: 35228
Joined: 4 Jan 2012, 6:25pm

Re: Mavic X138 rim crack

Postby Brucey » 5 Sep 2019, 4:01pm

FWIW those cracks look 'old' ie the cracks are discoloured / oxidused. They have clearly been there for some time.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
Sweep
Posts: 5514
Joined: 20 Oct 2011, 4:57pm
Location: London

Re: Mavic X138 rim crack

Postby Sweep » 5 Sep 2019, 4:15pm

Interesting brucey - thanks.
Live and learn.
I'm pretty good at keeping rims clean and inspecting tyre treads etc.
Learned a while ago to pay attention to sidewalls as well, and now I will make sure that I inspect rims carefully as well, particularly round the spokeholes.
Sweep