Ivandarken

I noticed a small split on the underside of the top tube of a nice vintage 531 steel frame... early 70's.

It is almost imperceptible, but I can feel a slight difference when I run my fingers across the split.

There is no damage to the frame otherwise, and I see nothing that would have caused it, so I am assuming that it was caused by an internal imperfection in the tube.

Has anyone ever had experience with this?
Does anyone know what would cause this... the bike has seen very little use and no abuse that I can see.
Should I be worried about frame failure?
Should I attempt some sort of remedy? If so, what?

beech333

Ouch! I'd play it safe and either get it fixed (worth it?) or strip it down/toss it out. I'd hate to hear you went 30+ mph down a hill and have it break.

unterhausen

that's very strange. Pics or it didn't happen.

Is it really a split?

JohnDThompson 

Picture?

Is it rusting?

Ivandarken

Hi guys...

Frame is worth it.
No rust anywhere on the frame.
I will try to post some photos right now to prove to myself that it did indeed happen... which I wish was not true.

... searches for camera and charger and countless wires and tubes...

ilikebikes

I had such a "crack" on the top tube of a very similiar frame, was told if I was just keeping it as furniture I was fine, if I planned on riding it I should have it fixed, or get rid of it, so I parted it out and sold the frame to a freind of mine for like $30.00, (yes he knew about the "crack") he built it up as a FG, sold it, (yes the buyer knew about the "crack") and the guy has been riding it hard daily since the day he bought it with no ill affect and no sign of the "crack" getting any longer or wider, does this mean it's just a matter of time? maybe, does this mean the bike will be fine? maybe, would I take the chance, no.

unterhausen

split implies to me that there is a crack running lengthwise down the tube. I don't see any reason for this to happen other than some kind of manufacturing defect. Never heard of anything like that, but given the production method of these tubes it wouldn't surprise me much. New guy gets drunk at lunch and things fall apart. Since the tt isn't stressed much, who knows how long it would take to become obvious

Ivandarken

No photos today... cords and tubes all at work.

ilikebikes... thanks for your experience.

The crack is literally a hairline of just less than an inch, following the direction of the tube (with the grain, so to speak).
It's hard to tell if the metal itself has separated... I can only say for sure that the paint has, and only by enough that a thick hair could cover it.
The fact that the metal has deformed ever so slightly makes me wonder what unseen forces caused this... or is still causing it. I would guess that it was simply under stress at the atomic level and chose to relieve itself at the weakest point.
The bike has been stored for over 20 years in a clean environment and had previous seen little use. I still have the original sew-ups in great shape.

repechage

Tube that should have failed QC. Mill score during the drawing process.

Stress built into the frame, coldworked (bent straight) and a bad tube. We don't like to think so, but many bikes were less than perfect during construction.

WAY too much heat upon building and a bad tube.

old's'cool

If you don't mind spending some money to find out the extent of the flaw and determine whether or not it needs/is worth fixing, take it to a machine shop and have it magnafluxed or magnaglowed. Assuming there is a crack, I'm not sure what a "good as new" repair would entail. Myself, I'd be inclined to "debraze" the top tube from the lugs, and replace it.
With a longitudinal crack, the tube's torsional strength and beam strength in that location is compromised. It is the nature of cracks, once started, to grow. Any external repair is bound to be ugly and cause other problems, such as annealing or stress concentration. Similar for internal repairs, which would entail removing (unbrazing) the top tube anyway, so at that point might as well replace it.
If all that discourages you from digging into it any further, if you're going to ride it as is, at least mark the ends of the crack and monitor it for growth (& report back!). Another option is to drill the ends of the crack, 1/16" dia, as stress relief to hopefully prevent further growth. The drill method only works when the tip of the crack is eliminated by the hole, so better to err in the direction of missing the crack (going beyond its externally visible end than have the internal tip of the crack extending beyond the hole you drilled because you couldn't see it externally.

Ivandarken

repechage; If I understand the process, which I barely do, that makes a lot of sense given what I am seeing.

old's'cool; That's a really good idea to mark the extent of the crack. Thanks. Have you ever drilled a tube for this reason? I know it is done for aviation purposes, but I had never heard of it done for a bicycle.... heck, before now I had never thought bicycle tubes could have these sorts of problems that weren't related to outside damage.

Thanks for all of your input. Keep it coming.

slushlover2

You may get more suggestions in the framebuilders forum. I'm sure someone there has seen this before. I have only seen tubes crack radially rather than lengthwise. I have gotten tubes replaced for around $150 not counting paint.

Ivandarken

I posted a link in framebuilders... maybe some of them will join us here with some additional insight.

old's'cool

Ivandarken, I have no experience with bike frames other than riding them! However, I have some dabblings in aviation & related industries where crack-stop drilling is commonplace. I do have first hand experience with this on my 1988 Chevrolet Caprice, which I noticed had cracks in the sheetmetal around the A-pillar area of the front door. I took this to be the result of inadequate design/analysis around the stresses of repeated opening & closing of the door. Before I had it repainted, I drilled crack stops at the extremities of each crack, and the cracks haven't grown since (~10 years), as far as I can tell.

Mike Mills

Get a loupe or strong magnifying glass. Better still would be an inspection microscope. There's really no substitute for a good "look-see" and some form of optic is required for this.

Fingernail test is meaningless, it could be nothing more than a scratch in the paint and it would "fail" the fingernail test.

What does it sound like? When you tap the tube, does it have the right sound or does it sound cracked? Honestly, you might be able to hear the difference.

randyjawa 

If you do not want to spend a bunch on a proper repair (new tube, paint, art = $$$), forgettaboudit! But keep an eye on it to see if the crack is extending. The idea of drilling each end of the crack is a good one also since that will arrest the crack from running further - hopefully.

A longitudinal crack might not present a safety issue and I would definitely ride the bicycle, again keeping an eye on it. I doubt that this situation will fail in a dramatic fashion. You will have lots of warning that things are getting worse. If nothing gets any worse, keep going. If the crack extends, replace the tube or...

Drill the ends of the crack. Take the bike to a good welder and ask they he or she braze or silver solder the crack. If you are not near a lug, use silver solder which requires less heat. The paint will be shot at the spot and for three or four inches each in each direction but the cost will be minimal. The crack will still be there but it will not get worse.

That's how I would do it and for very little cost, when compared to replacing the entire tube.

cs1

I was thinking the same. So, figure at least $350 for a new tube and bare bones paint. Is the frame really worth that much?

Ivandarken

Here are some photos of the split. Okay, people, what do you think??? Remember, this is not just a scratch in the paint... if you run your fingers over this spot you can feel the eruption of the metal.

[IMG][/IMG]

GV27

Only comment I have is "man, that's weird". I had assumed that the crack was adjacent to a lug rather than out in the middle of the tube. Is it just a scratch maybe?

norskagent

are you sure its 531 and not some type of seamed tubing?

gearbasher

Are you sure it's 531? Maybe it's a seamed tube that is splitting along the seam? 531 labels are easy to come by. Someone could have labeled a lower quality tubeset. It's been done.

Edit: norskagent, beat me to it. I guess, brilliant minds think a like.

Fletch521

Looks like seamed tubing splitting at the weld.

Ivandarken

Definitely a 531 tubing. No doubt.

Split is near the center of the top tube, not near the lugs.

Definitely a split rather that a scratch in the paint... the tube deforms outward slightly which would not occur with a scratch.

I am feeling that Repechage is right about the reaming process of the tube construction. Probably got too close the edge during the process and the tube reacted much later.

MetinUz

I can see a slight irregularity in the surface. Is it possible that the tube was improperly clamped to a workstand or such? Perhaps you could use an xacto knife to remove the paint down to metal for a few milimeters along the crack, then sand it lightly if necessary? Recently I was sure that a rim was cracked on the braking surface, but a light sanding revealed that it was a surface scratch instead.

MnHPVA Guy

If it were mine I'd;
Determine where the ends of the crack are. In the metal, not the paint.

Drill 3/32" holes just past the ends.

Make an oval patch of similar tubing about 1/2" wide and an inch longer than the crack.

Attach with BAg-1 silver brazing filler (45% silver, w/cadmium) or a high strength silver bearing solder like Harris Sta-Brite.

If it were a customer's I'd replace the tube.