Hello,

After a few years of non-use, I've decided to rebuild my 1981 Colnago Super. I've stripped it down to the frame and started to look it over to make a decision about touch-up/repaint. What I noticed shocked me. It seems that the seat tube is, for lack of a better term, imploding in various places. The first area I noticed was right where the clamp on front derailleur was. I wrote it off to the clamp but then I noticed a couple of places on the trailing side of the tube, higher up. This morning I noticed that there's also a pair of "dimples" right below the lug. They are always in pairs.



The bike has never been crashed.

My question is have you heard of this happening and if so, what causes it? I would have to believe the seat tube will need to be replaced. Which will mean a full repaint, as well?

Thanks for any information you can provide.

Mark

The lower marks in the FD area are probably from over tightening the FD, the upper marks could be from over tightening a repair stand.

Might be worth it to check for any crazy corrosion maybe going on inside the frame tubes that could cause it to collapase, but It's more likely that the frame was hit or fell on something while it was in storage if you are sure they weren't there before you put it away.

Chombi

That sucks, looks like time for frame repair! If it's not corroded inside, maybe you could roll the dents out with frame blocks?

I agree with the assessment of the FD over tightening. That's the first thing that came to mind when I saw it. I have an older stand that clamps on the down tube (and rests on the BB) and this frame rarely saw the inside of a shop. I have to beleive it's something else.

I'll check for corrosion, thanks. the bike was hung by the rear wheel for the past decade.

Thanks for your quick replies. I appreciate it.

I might have wrote off that stand theory a little too fast. There was once, in the early 90's, when I had a shop give it a complete overhaul. I didn't like their work (reputable shop, thou) and he convinced me to ditch my GEL 280's for some clinchers. Bad move. I believe he swapped hubs on me as well. That being said, there is the spot at the lug and the dimples are on either side of the point on the lug. I'd take a picture but the seat stays block the view. I can't imagine a stand clamp fitting there.

Also, I checked for corrosion. I don't see anything that looks abnormal, not that I've looked inside this frame very often.

Again, thanks.

Can we see some more pics? The lug spot and a shot of the twin dimples with the FD back in place? I think without the FD in place there's some confusion here.

The way the pics appear to me, those two dents occurred when something was clamped to the frame - something with an open end facing backwards, not like on an FD that would have its open end on the non-drive side of the tube.

No other marks, so it also doesn't appear it was anything else (like a bottle carrier or something) that you yourself had mounted on the tube. I think it's highly likely a shop did this with their stand. Shame on them for not pointing it out after they did it, too.

DD

Agreed.

Ham fisted and dishonest to boot.

Can be hard to regulate these things, but only a couple of mechanics get near my bike other than the kids or I.

The ones that do work on them at the shop are incredibly talented.

I have a ground steel rod that is like 27.0 mm by accident, I have used it with good effect in pushing dents like this, I radiuses the end a small amount and oil it up, then work it down to the problem area, I also marked the rod to the probable butt section of the seat tube. and use that mark as a go no more point. Beware if your frame is SLX then be conservative on where the inside dimension changes, maybe just below the derailleur clamp area.

Very interesting. I replaced the FD and it seems that the two sets farther down are just above and below the FD clamp:




As for the lug, maybe overtightened seat post bolt?



There was never anything clamped to

the seat tube (bottle carrier, etc...). There was only a Silca pump wedged in parallel to the ST.

Again, thanks.

mgw

That's a fantastic idea for a fix-tool

If the OP is certain about his frame being an '81, I don't think he has to worry about the tubing being anything other than Columbus SL or SP.

mgwilder: Your links do not appear to be working.

DD

I'll try to redo the attachments when I get to work. It looked fine in the preview.

I believe it's an '81 from everything I've read. I bought it in early '84, so it might have been sitting around for a while. Cable routing on top of the BB, "Colnago Super" as a "chrome" decal on the drive side chain stay. Flattish fork crown (not aero). If I can figure out the whole attachment thing, I'll post some other photos as well. It's an odd color and I've never seen another one like it.

It's a 52cm, so if in fact it's an '81, it should be SL. Oddly, there is no tubing identification on the frame.

Let's try this again...Here are the two sets of dimples, lower on the seat stay with the FD attached:



It seems that they fall just above and below the FD.

Here is the pair just below the lug on the trailing edge of the tube:



Last night I thought it might have been from an overtightened seat post bolt but with the balance of the seat post in the tube, I'd find it hard to believe it would have imploded with the post in there.

I'll post additional picture of the frame later.

mgw

I think both sets of marks are from a stand clamp. There is no way either a over tightend FD clamp or a seatbinder did this. Damage from a overtightened FD clamp would be right on the clap area where the bolt is. The 'ears' would likely break before an over tightened binder damaged the tube 3" below it.





I also don't think they are serious to warrant a tube replacement but using some frame blocks as suggested may be a good idea.

The dents seem to be lined up and very similar in shape and size to each other, like maybe a service stand clamp that was first used on top of the seat tube area and then either slid down the seat tube to near the FD clamp adjust the bike's position on the stand vertically. Seeing the lined up dents and how similar they are, I also vote service stand clamp damage. A newbie mechanic might have over tightened the clamp adjuster thinking that the seatpost inside will provide enough support inside the tube to avoid denting.
It will be a hard fix using frame blocks as the dents near the seatpost clamp are will be hard to get at. Unfortunately, eliminating 100% of the dents will most likely require a full replacement of the seat tube. I wonder if the SLX rifling might also get in the way of trying to ease the dents from the insed with a metal rod as also suggested.

Chombi

If it's an 81 Super, it won't be Columbus SLX.

SLX wasn't introduced until roughly 1984.

Frankly, I'd use Repechage's idea, touch up any paint chipping after that process and build the bicycle.

Likely to make a great rider.

I've had two 1981 Supers and they were nice bicycles.

+1. I don't believe there will be any paint damage. I don't actually believe the dents will come all the way out, but will be much less noticeable.

This damage is a serious bummer, but I don't believe it makes the bike unsafe. The damage done is mostly to the frame's value, which is closely connected to the condition of the paint (if original). Therefore I would avoid any "repair" that will hurt the paint, such as rolling the dents with blocks.

Oops!, I don't know how SLX popped into my mind when I was doing my reply, Must be that cool Paganini bike thread I was reading earlier..... Thanks for the correction!

Chombi

I guess it's been sorted, but those marks look identical to the clamps on a very old Park stand I have.

Agreed.

No worries.

I just feel bad for the op, as that's a cool frameset.

I do like these old Supers a great deal.

My old Park wall mounted shop stand could easily leave those marks.

It's a beast.

I won't go near the clamp with any of my modern tubed bicycles.

I usually just rest it by the nose of the saddle.

Thank you all for your replies. I really appreciate it. I'll look into finding a bar like repechage has and give it a go. I'm the original owner and this bike has deep sentimental value. Once I take care of this, I'll have to figure out the paint and go from there. It's a rather unique color and I have never seen another like it. The pictures don't do it justice. When I start the rebuild I'll create a thread. Again, thanks.

Mark Wilder

The dents at top will come out easy with a junk/spare seatpost that is same diameter as original, likely will scratch up the seatpost however so dont use a nice one. If the dents are still noticeable with the seatpost inserted past them, carefully use a plastic or wooden mallet to tap around the outside of dent in order to pop the low center back out.
For the lower set, probably best to make up a special tool consisting of a 2" short section of seatpost size tubing attached to a much longer and slightly smaller diameter tube and attach a slidehammer to top of the tube if needed to withdraw.
If you tried using a 3' long section fo strait seatpost size tubing to reach the lower dents, it would probably get very stuck.

Water bottle bosses would complicate removal of the lower dents but it looks like this frame has none.