[Jet-Mech]

Hi team . I was just looking closely at the T2 whilst I was tinkering today. I noticed that some of the welds seemed to be a bit marginal. This weld is one of the two that fixes the swingarm triangulation piece between the seatstay and chainstay on the non-drive side. I have two issues.

Firstly, the weld is about ¼” above the surface of the chainstay yoke. I thus presume that the triangulation piece welds onto some sort of stub on the yoke?

Secondly, the weld does not form a complete line around the circumference of the triangulation piece. There is a distinct gap of about 1/8” at the back.

Anyone else notice this on their Trance or Reign ? I am not too worried, but it is something that caught my eye. It is a bit hard to see from the photos, Sorry !

 

[Pinky]

I just checked my R1 frame , the weld is further up from the bottom than on your Trance , but that could just be the difference between Trance and Reign. But , it is fully welded at the joint you speak of.

Sounds like a QA oversight. I can't see why they would leave the weld incomplete. Having said that , I wouldn't be too worried about it , just keep an eye on it in case something ugly starts down there !

 

[40hills]

Just to be sure, I would go to any Giant dealer and take a look at the other Trance frames... see how they compare. If yours is very different in a bad way, then show it to the dealer and have them call Giant.

 

[Jet-Mech]

G'day Pinky / Rich A , I will probably pay a visit to the LBS in the next few weeks to get a service done and have a bit of a snoop around. I won't panic too much as the weld in question is not really under that much stress; and that part of the bike is not critical. I guess there is always the warranty to fall back on. Anyway, I was just curious to see if others had the same thing on their Reigns / Trances.

 

[kingswoodkc]

Just to be sure, I would go to any Giant dealer and take a look at the other Trance frames... see how they compare. If yours is very different in a bad way, then show it to the dealer and have them call Giant.

Looking at your photos, I am quite sure that they indicate a very serious quality problem. I have owned four Giant bikes, one of each is a Trance and have never seen such a poor quality weld.:nono:

I suggest you to email those photos to Giant USA and then have a chat with them!

 

[mark_8408]

On my trance 2 the welds are very clean. None of them looks like the one in the pic.

 

[FatTance]

I'll check mine when i get home;

But with the little I know about welding it is the burn between the two joining metals that matters not the slag we see on the outside. I have only welded mild steel and when experimenting I would intentionally would try the break the weld. Even if you got through the weld material, if the weld was done properly the two pieces of metal were bonded. If you got it to break the crack would form outside of the weld area. Take look at most of the cracked/broken frames you see on this site and I'll bet you find they are cracked outside of the welds and in the tubular area, even the ones cracked at the joints. My Rainier top tube cracked at the seat tube joint, but the weld area was in tact.

I don't think I would worry, but it never hurts to ask. Someone may have a similar trouble, not to mention that Giant is pretty good on their frame warranties, At least that has been my experience. One Rainier frame and one rear triangle for Trance 2, bearing related.

By the way my Trance 2 has carried my 300 lbs for about 1200 miles over rooty and rocky single track. Occasional but not very often small air up to 1 foot. Don't want to push my luck.
Any TIG welders out there to way in?
:yesnod:

 

[tungsten]

Looks to me like a contaminated weld.

Don't trust it, take it back!

 

[Jet-Mech]

Hi team ! Thanks for all the valueable replies. I will mention the welds to the LBS when I am down there next. I think my best move is to send the photos onto the Giant people in Australia. It seems as though a few of the welds on the swingarm have the same appearance. It is almost as though Giant lay down the paint real thick on the swingarm.

Is a bulbous weld appearance indicative of contamination ? I am under the impression that a weld should look like an overlapping stack of coins? Even if a weld does look like a stack of overlapping coins, can it be contaminated? Should I be concerned with the rest of the frame?

Thanks again for your advice team, MTBR is about the only place to get good informative unbiased information these days :thumbsup: !

P.S. Should I talk to Giant first or the LBS??

 

[Pinky]

I'm a boilermaker (welder) and have been in the trade for over 20 years now. During most of that time I have been on the TIG torch working with a broad range of materials including stainless , alum. alloys , cro mo and even a little titanium.

Due to the thick paint on Jet Mechs frame , its impossible to tell if there are any problems with the weld in question , but apart from a little cold lap (1st pic , closest point to the camera) , it looks fine. Contamination of any sort will cause porosity ( lots of small air bubbles in the weld metal) and will generally be caused by oil / grease , dirt / crud or lack of shielding gas during welding. Aluminium needs to be very clean before welding. Having said that ,I have never seen a porous weld on any alum. bike frame in my life.

Sure , porosity can be hidden with a thick coat of paint , but it is very easy to see prior to paint and I doubt a porous / contaminated weld would get too far down the line before being binned by the QA guy.

Fat Trance is referring to the heat affected zone , the area along the edge of the weld bead known as the toe. Heat treatment after welding will remedy some of the weakness caused by the actual welding process in this area , but it is still the most likely place to develop a crack. I'd hazard a guess that Cannondale have addressed this issue by smoothing out their welds to reduce the stress loads along the weld toes. Something I don't agree with but thats another story. Oh and TIG welding doesn't have a slag coating , your thinking of arc welding using electrodes. Inert gas shielding does the same job as the slag , keeping the molten weld pool free of atmospheric gasses.

Jet Mech , I think your LBS should be your first port of call , in fact I have heard that Giant Aust. are difficult to get in contact with at all. They let the bike shops do the initial assesments in possible warranty cases. Again something I don't agree with ,.....but thats another story.....

 

[Jet-Mech]

G'day Pinky , Thanks again for your valuable advice. Hell, with your experience, if you're happy with that weld so am I ! Any way, it does put my mind at ease if you think it is nothing to worry about.

Why exactly do you not agree with Cannondale's filled in welds? From what I learned at uni, a smooth transition between the intersections of different cross-sections is essential for reducing stress raisers.

The paint issue may be valid in my situation. The main triangle welds look good with a corresponding quality paintjob. The swingarm however has a few of these bulbous welds and the paint does look much thicker. LBS will be in the loop very soon.:thumbsup:

P.S. I don't want to buy into this whole made in Taiwan business, but what if the QA guy (may not be paid / trained too well) was sloppy and passed the swingarm?

 

[tungsten]

It's gawd awful looking. The weld in that spot on my Reign has small, evenly spaced little puddles...........
Looks like the guy had some trouble w/contamination, gave it a couple swipes w/his wire brush and then two-passed it. Look at how the weld just behind it flows into both work pieces. That's how it's supposed to look.
Like Pinky said, that's the place where it'd be most likely to crack.
I'd ask for a new swingarm.

 

[Pinky]

Why exactly do you not agree with Cannondale's filled in welds? From what I learned at uni, a smooth transition between the intersections of different cross-sections is essential for reducing stress raisers.

Yep , totally agree with that theory , but how do they get enough material there so as to produce a nice big radius ?

I'm not familiar with Cannondales process , so this is pure speculation > Take the head tube / top tube junction for example. Assuming C'dale fit their tubes up like everyone else ( regular tube branch joint ) , do they just keep pouring weld in there until there's enough material to cover the radius area ? If so , thats a huge amount of weld metal , especially in light Al. tubing. An un- necessary amount of weld (and heat) , I believe.

They may flare their tubes at the ends to achieve some of the finished radius then weld around the joint and smooth off. That would seem more sensible and a lot less labour for the weld grinding guy !

Either way , their design must be very marginal to justify their "radius joint method". Everyone else gets by with regular fillet welds and appropriate wall thickness at the joints.

If anyone can fill me in on Cannondales fabrication methods , I'll be more than willing to eat my words if need be I'm not anti Cannondale , it's just that they seem to have gone to a lot of effort to be different to everyone else and I can't see that there was that big a problem in the first place.

Anyway , enough rambling , back to the thread......

 

[Jet-Mech]

G'day Pinky / Tungsten . I had another look at that weld today, there is a stack of coins look to it, but I tell you what, it looks like a stack of bloated coins ! The first thing that actually caught my eye was that the entire weld was above the surface of the chainstay yoke. Closer inspection revealed that the weld was not pretty.

I remember someone saying that Cannondale feeds in a lot of filler rod to get the necessary bulk in their welds. Some poor person then grinds and finishes them by hand. I do see your point about excessive heat Pinky. I will go to the LBS in the next fortnight and see what they think.

 

[LyNx]

OK, I was going to keep out of this, but it's dragged on for a bit so I'm gona post up some pics from my Trance rear triangle welds - this will either add fuel or water to this whole discussion . Personally I think if Jet-Mechs pics had been taken from lower down it wouldn't look as bad (like the angle mine weree taken at) Personally I wouldn't be too worried about it at all, but I guess a visit to a GIANT dealer will give you a better idea - it's just a slightly "big-boned" weld is all.

 

[LyNx]

BTW, that's an '06 model isn't it?? Maybe it's GIANT's way of trying to improve the paint from the crappy '05, look at wrong and it wears away type paint jobs.

 

[Pitto]

take a look at my image, i think its like fig2 oposed to fig 1

G

 

[Bad Santa]

Hey Pitto, with drawings like that you must be an architect. :thumbsup:

 

[Pitto]

or worse, a project manager...........



G

 

[Pinky]

Heres a pic of the weld on my Reign for comparison. The stub that Jet Mech mentioned in his first post , must be longer on the Reigns , the weld is further up.

Pitto is on to it with his pic , I'd imagine the stub goes up inside the tube maybe 10mm or so. This means the weld is under less load , only having to retain the 2 parts whilst the stub simply locates them. It would assist in easy assembly in the factory too.