Cal398

I have a 9-speed record group and on the chainring, where it attaches to the spider, there are long cracks on the inside facing edges of the "cut out" area. So where there's the cut-out triangle, there are long cracks on the sides that face each other. Going around the whole chainring, it looks like there are 9 total.

Edit: I got my ten posts, editing to add the photos.

Photo 1: https://postimg.cc/751QszNK
Photo 2: https://postimg.cc/d7qNz0Hw

Is it toast?

WGB 

No one wants you to throw out a useable Campy chainrings, perhaps you can load photos under your profile by clicking on CAL398, then on "view public profile", then on right side of page, add albums.

dddd

I've seen Campag chainrings appear to delaminate as described, supposedly this is exacerbated by exposure to the elements and is caused by corrosion.

Rolled metals can have such planar porosities that aren't usually found in castings, it's a path for moisture and electrolytes apparently.

Cal398

Thank you dddd ! I added the photos above, is that consistent with what you're describing?

Maybe the answer is obvious, but does delaminating mean I should replace them?

machinist42

(I see nothing...disconcerting: ride on.)

scarlson 

here's mine



This one took 4 years of moderate use to go from unnoticeable to like this. It didn't fail catastrophically and I don't think yours would either. Was discovered because of derailleur rub.

Never seen any other brand do this. You'd think they'd have switched metal suppliers!

Drillium Dude 

I see it, but I think it's just a residual mark from the stamping process. Of course, a photo which allows for a bit more of a close-up would help confirm beyond a shadow of a doubt.

Having said that, IMHO the teeth appear to be getting quite worn - I'd be retiring that ring soon for that reason.

DD

repechage

Have seen the earlier chainrings do that, almost always from a bike near salt water.

on the 9 speed ring, Simple Green or Zep used to clean off the grease?
Simple Green is a bad product as seen by the aircraft mechanics, there is a special formula for aircraft use.

the chainrings are one of the 7000 series alloys and the delaminating is characteristic of the metal when exposed to alkaline? Corrosion
I forgot all the details.

Cal398

Thanks all! That would make sense, as this bike has spent almost its entire life on the California coast.

I'll give it a scrub and monitor it. I'll update the thread if something changes dramatically.

davester

Ditto. I think that this is a common occurrence. There are similar marks on the lightening holes of high flange hubs. I have known a few folks a bit over the top on cosmetics who use rat tail files and polishing materials to smooth these marks over.

Drillium Dude 

And now you know another one

DD

Drillium Dude 

This photo illustrates what I believe is actually going on with the OP's chainring:



Nope - those are not cracks. Also note the ring is NOS, so it's not been subject to any sort of stress in its lifetime.

DD

juvela

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the forum had a thread several year back regarding a machine which had been stored on the California coast in Mendocino county

it was all Nuovo Record equipped and the salt air had got this process going at a heck of a rate

if the bike were a cancer patient it would have been "stage four"

much of the dural had not only "delaminated" but was gone - all the components completely ruined

do not recall for sure what marque the machine was - want to say it was something CH such as a Mondia

have attempted searching for the thread in the past without success

perhaps another reader will recall it...

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repechage

thanks DD, actually I had bypassed the die marks, wearing punch die set. The front surface of the OP’s chainring is possibly beginning to show stress.
my inquiry about Simple Green was not answered. If one uses that stuff it has to be super rinsed. Like 3X and hot water. Only leave it in contact to do its job, unlike a solvent dunk that can be unattended for a while.

Cal398

I’ve never used any strong solvent like that to clean off my bike - always just some dish soap and elbow grease. Good to know though!

gearbasher

I've had Campy chainrings that looked like that. I'm still using them. I've also had Campy dropout alignment, BB and headset tools start to delaminate. I'm still using them.