Narhay

My new ironman has some cracking around the seat lug clamp bolt ears. Paint or not? Common? Concerning?

I figure the worst case scenario is it cracks off, I cut and file both off and replace with something like this:

Vintage_Cyclist

Looks like a touch-up paint job cracking. I'd clean the area off to see if there's rust, treat it and re-touch-up paint. I've got an 85 and 88 and both have been prone to rust on and around the seat lug.

Colnago Mixte

Is that seat post the right size? Looks a little small, and if it is, that would explain the damage to the ears.

juvela

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+1

This is what I was thinking as well.

Sometimes if the opening has a bit of out of roundness or a drop of brass inside it can be dealt with by going down a size on the pillar when the correct fix is to run a reamer in there and get things round. A reamer does not have to be an enlarger but in this case a clearer to get things round.

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malcala622

I had the same thought as Colnago Mixte. Seems theres about a 2mm gap for the seatpost size.

belacqua

For several years I have watched a similar pattern on my 87 Mongoose ATB b/c I read that frame cracks here were a known issue on those models.

My conclusion has been that, contrary to those reports, it is simply cracks in the paint. The paint is particularly thick and inflexible here because it forms a meniscus at the interior angle.

I don't have the actual facts on it, but my own worries certainly went away with time.

repechage

My guess, only paint at this point, BUT wonder as other have about the seat post size.
If the post is original it exhibits marring from a less than round and smooth seat tube.
I would ream it carefully to be sure and at the minimum get rid of the burrs.
Plenty of time I have seen seat post of the next size down substituted as they fit the minor axis of the frame.
I have a hunch dressed round it will accept the next size up and you will be good.

The style of seat lug ears shown are not my favorite for a quick release seat binding bolt.

Chombi1 

I'm wondering if the seat clamp lugs are cracking off because of the cycling of the seatpost quick realease between tight and loose if you adjust or take it your seatpost often enough. On most bikes people adjust the seatpost just a couple of times and then leave it alone for sometimes the life of the bike with them. Bikes with QRs on their seatpost clamps might go through more adjustments/install/removal cycles...
Just my thoughts.....

Charles Wahl

^^ I second that emotion. Also, the left side looks like it might be the tube that's cracking.

Narhay

The seatpost is 27.2. This seems consistent with the other ironmans of the era.

repechage

dress the burrs, ditch the QR seat binding bolt.
break away the cracked paint and double check for cracks.
Double check the 27.2 seat post actually is 27.2.
The only brand I have trusted on that is Campagnolo.
Only times I have double checked is when a purchased bike has just a "too shiny" seat post.

gugie 

I doubt if this will work. The lug doesn't extend far enough to clear the top tube.

As others have noted, remove a bit of the paint to see if it truly is a crack. If so, it wouldn't be too difficult to grind/file/sand off the old one and braze a new one on.

Narhay

The ironman lives on. No cracks, just touch up paint on a poorly filed braze joint. Now I have to touch up my heavy handed uncovering job.

gugie 

nlerner

If the Internet isn't for hasty and ill-informed judgments, what good is it for?!

gugie 

coolkat

Ok, I just picked up an older mountain bike that has similar ears (and, incidentally, similar cracking that I'm ignoring). I'm used to seeing the style with a notch, but this one has no notch and has a very small diameter--too small to accept a normal notched binder bolt. I HATE QRs on seatposts, but I'm not really sure there's another option here...anybody have an example of what I should be looking for? It looks a bit smaller diameter than OP's.

Fahrenheit531