can this be fixed by welding?

[fogrider]

saw this listed on cl...I don't think it can be fixed by welding...I think the tubes are too thin. welding is for joining tubes together at their ends. I think the tube has to be replaced.

http://sfbay.craigslist.org/pen/bik/1666235950.html

[sokyroadie]

Odds are that it is straight gauge tubing, so it is as thick at the crack as it is on the ends. I personally would not trust it if it were welded due to the location of the crack.

Jeff

[oldpotatoe]

saw this listed on cl...I don't think it can be fixed by welding...I think the tubes are too thin. welding is for joining tubes together at their ends. I think the tube has to be replaced.

http://sfbay.craigslist.org/pen/bik/1666235950.html

If titanium cracks like that, at the weld, means it was welded poorly by the welder and no telling where else on the frame it was also 'cooked'. I'd stay away.

[jpw]

It's wind chime fodder, a mega wind chime.

[David Kirk]

Tube needs to be replaced to make it safe. I'd walk away quickly.

Dave

[Kish Fabrication]

Please don't buy that frame.

Often when you see cracks like that in a properly designed ti bike it points to bad material/prep/welding practice, which probably isn't confined to that one joint. So, even if this one was dealt with properly you can expect more cracks further down the road.

[jpw]

Is it a Merlin/ Litespeed frame?

[Tobias]

If any part is stressed enough it will fail at some point, and that's usually at the weakest place. Welds no matter how great they are can leave a stress concentration which is a great place for a crack to start. This doesn't mean the quality of the welds were necessarily bad.

Having said that, I don't think replacing the tube is a good idea because it would require removing the weld and then welding over the same place on the head tube. And the same at the other end. That's just asking for trouble on a frame which is "fragile" enough to have failed in the first place.

I'd treat it as junk, and I'm surprised it's being sold at all. That's not to say it can't be welded, polished out, and used by a casual rider around a neighborhood. It just wouldn't be me.

[jpw]

That's not to say it can't be welded, polished out, and used by a casual rider around a neighborhood. It just wouldn't be me.

It shouldn't be anyone. That frame is dead.

[fogrider]

Please don't buy that frame.

Often when you see cracks like that in a properly designed ti bike it points to bad material/prep/welding practice, which probably isn't confined to that one joint. So, even if this one was dealt with properly you can expect more cracks further down the road.

I'm not looking to buy this frame. I've seen cracks like that on a few other frames...once on the downtube right where the shifter bosses are (shows how old the frame was). seems like Tobias is right that every weld has its limits... but one would think it should hold up to the forces of cycling...I'm paying more attention to my frame now.

[RPS]

seems like Tobias is right that every weld has its limits... but one would think it should hold up to the forces of cycling...I'm paying more attention to my frame now.If it "always" did, wouldn't someone push the limits further by making it even lighter?

amazing light frame seems to be under or just at 1 kilo The note suggests 2.2 pounds or less for an "older" frame. Granted it's small at 52 CM but that doesn't mean previous riders were light themselves. And for all we know the frame could have been abused on a regular basis.

[gone]

Looks like the seller may have thought better of passing on a damaged frame.

[Kish Fabrication]

I'm not looking to buy this frame. I've seen cracks like that on a few other frames...once on the downtube right where the shifter bosses are (shows how old the frame was). seems like Tobias is right that every weld has its limits... but one would think it should hold up to the forces of cycling...I'm paying more attention to my frame now.

Every joint has its limits, yes, but if the joint is prepared and welded properly the weld itself won't be the weak link in the chain. Also, without getting into a lot of detail, a well-designed titanium frame will never see the limits it is built around, provided it's not wrapped around a tree or car bumper. Normal use won't wear it out no matter how old it is.

But that's beside the point, hopefully the frame in question has moved onto another life as garden art.

[Tobias]

Every joint has its limits, yes, but if the joint is prepared and welded properly the weld itself won't be the weak link in the chain. Also, without getting into a lot of detail, a well-designed titanium frame will never see the limits it is built around, provided it's not wrapped around a tree or car bumper. Normal use won't wear it out no matter how old it is.

But that's beside the point, hopefully the frame in question has moved onto another life as garden art.
This sounds better in theory than in practice when compared on an equal basis. The main reason a weld is stronger most of the time compared to the rest of the tube is because of butting. If not for the thicker walls at the point of the weld failures would almost always be at the welds.

Even with the advantages of butting many frames still fail at the welds. I don't even recall a titanium tube fail in the middle away from a weld or away from the butt transition where there is stress concentration.

In industry where tubing systems are complex and critical they are performed by the best of welders, and most failures there also occur at or very near the welds.

In no way am I critical of the welders, but rather the very opposite. Because welds are the inherent weak point (unless significant butting) it makes them that much more important to get them right.

[Kish Fabrication]

This sounds better in theory than in practice when compared on an equal basis. The main reason a weld is stronger most of the time compared to the rest of the tube is because of butting. If not for the thicker walls at the point of the weld failures would almost always be at the welds.

Even with the advantages of butting many frames still fail at the welds. I don't even recall a titanium tube fail in the middle away from a weld or away from the butt transition where there is stress concentration.

In industry where tubing systems are complex and critical they are performed by the best of welders, and most failures there also occur at or very near the welds.

In no way am I critical of the welders, but rather the very opposite. Because welds are the inherent weak point (unless significant butting) it makes them that much more important to get them right.

I have a feeling we are saying the same thing, but a clarification needs to made. 'At' the weld, and 'very near' the weld are two very different things. Of course the weak link is going to be at the joint, but a properly welded joint will not break at (or in) the weld itself. It will break a little off the toe of the weld. Maybe only by a millimeter or two.

I have personally broken or overseen the breaking of hundreds of test joints in titanium, and a poorly prepped, poorly purged, starved or cold joint reveals itself by the manner in which it fails. 'In' the weld, not 'near' the weld.

[RPS]

I have a feeling we are saying the same thing, but a clarification needs to made. 'At' the weld, and 'very near' the weld are two very different things. Of course the weak link is going to be at the joint, but a properly welded joint will not break at (or in) the weld itself. It will break a little off the toe of the weld. Maybe only by a millimeter or two.

Sometimes that can be a very important distinction. Rarely do we see steel or titanium tubes fail in the middle, even when they are stressed. ;)

[Kish Fabrication]

Sometimes that can be a very important distinction. Rarely do we see steel or titanium tubes fail in the middle, even when they are stressed. ;)

I don't understand why you bolded what you did....Sometimes what can be a very important distinction?

[RPS]

I don't understand why you bolded what you did....Sometimes what can be a very important distinction?
Because it highlights the fact that the mid sections of main-triangle tubes normally have excess capabilities that can be put to good use. ;)