I have a cracked frame and I'm trying to determin if it's caused by abuse (as the manufacturer says) or a poor weld (as other people seem to think). I can PM or email you pics. I don't want to post it publicly because I don't want to make a company look bad, especially if it is abuse. Thanks.
Calling engineers/welders: frame crack cause
- Thread starter nickaziz
- Start date
without seeing a picture it's impossible to judge, can you post a close up such that it doesn't reveal who made the frame?
Generally if you can see little bubbles in the broken weld or if it looks like the weld peeled off of the tube it's a bad weld. Welding isn't really rocket science in that an experienced welder knows if he's doing a good job or not, if the manufacturer claims your frame broke from abuse then it probablly did.
Generally if you can see little bubbles in the broken weld or if it looks like the weld peeled off of the tube it's a bad weld. Welding isn't really rocket science in that an experienced welder knows if he's doing a good job or not, if the manufacturer claims your frame broke from abuse then it probablly did.
The manufacturer has not seen the frame. It's an assumption based on the description. I will PM or email the pics to people if they feel they can be of help and yes they are close up. The crack runs directly beside a weld right along the edges. (Not in the weld itself)
Post pics!!!!! You're not giving any negitive press about the manufacture. Yours may be a bad frame, or maybe there are several frames out there with the same issue, which could be helpful to the people that own them.
If it's right next to a weld it sounds like a frame defect to me, maybe in the heat treating process. The weakest spot in the metal is right next to a weld, because the heat from the weld alters the structure of the metal. Heat treating is supposed to reverse this effect, but maybe something funny happened with your frame during the process.
Or maybe I'm just spouting nonsence, there's probably people here who know A LOT more than I do...... I'm just an engineering STUDENT.
Or maybe I'm just spouting nonsence, there's probably people here who know A LOT more than I do...... I'm just an engineering STUDENT.
What tube junction is that???
NO, and there is alway a heat affected zone around the weld (HAZ)nickaziz said:
In a proper design, the wall thickness should be thicker to compensate for the weaker material.
However, since it's steel, it should be repairable if it hasn't seperated yet.
Yeah, the heat treating is supposed to be done after final welding to strengthen the metal.
What fork were you running?
What fork were you running?
I am not ging to fix this frame in a permanent way. It will either be replaced under warranty or i will pay for crash replacement. The crack has seperated a fair bit i would say, and the top tube has a small buldge in it. I may get it welded until a replacement arrives, if the manufacturer approves.buildyourown said:
Would you agree that the frame has been abused if that's what the manufacturer told you or have you sincerely only ridden this bike as it was intended to be ridden without any major crashes? Really you should be able to judge rather the crack has developed as normal wear or if it's a defect. I'm inclined to believe that, being a steel frame, the crack has come from a design issue if you really haven't abused the frame. Only you know what you were doing on the bike when the crack appeared though.
If a frame is going to break it's either going to be right there at and along the weld(especially on a straight gauge 4130 frame), or from a tube buckling (highly unlikely on a straight gauge 4130 frame). So the break itself doesn't mean it's defective. More important, as Kornphlake pointed out, is what type of use was the bike designed (or claimed) to be for? and what were you doing with it?
OK, level with us.nickaziz said:
Is this from average riding, or from 8' drops to flat? Very few frames can take that sort of stress over and over. ALL frames will fail eventually, it's just a matter of how much you speed up the process.
Is that a Surly? Just a guess from the paint.
zane said:
Nobody does a post weld heat-treat on 4130 bikes.
Depending on the bike, I wouldn't rule out repair. I have repaired much worse.
You can also add a gusset to the area to make it stronger than before.
'Nuff said.nickaziz said:
I've seen many frames crack from "JRA". It's not from just riding, it's a cumulative effect of everything you've done to the bike - it just happens sometimes when there is very little stress on the frame right at that moment. Spokes break for example alot of times when you're just cruisin along. The cumulative stress can't be seen until the part fails. Add to this a hugh stress area like a head tube, and whammo.
I'd say if it cracked like that, the rest of the frame might be stressed out too. New bike time.
Well, if you are interested in a repair and the manufacture won't hook you up, let me know and I can direct you to someone who can do it right.nickaziz said:
When does the heat treating occur? When the tubes are all un-welded?buildyourown said:
after the welding process (i.e. post weld). what fork was on the bike? what kinds of riding have you done with it so far?
zane said:
Heat treating is a general term. Regular 4130 bikes are made from condition N steel. This means the tubes have been "normalized" to relieve the internal stresses left over from drawing. Some higher end steels (TT Versus HT)have been heat treated. This makes them stronger but it also makes them more brittle. Good for some apps but bad for others. Other steels (853, TT OX Platinum) air referred to as "air-hardening" which means they actually get stronger in the HAZ provided the correct joining method is used. I have never heard of a manufacturer heat-treating cro-mo after welding. Basically, the tube structure of a bicycle is so complex that it can not be heated to 1100 deg and quenched without cracking or warping so badly that it is useless. This isn't an issue with Alum since you only need to go to 300 deg.
the "after the welding process" part was in reference to zane's question about "when does the heat reating occur?". yes, after the frame has been welded together.
Man, we have some intelligent monkeys on this board. I'd have to agree with them, because the crack is around the HAZ, my best guess would be they used a touch too much heat. By doing this, reduced wall thickness and repeated severe stress on that area fractured it. While this would make sense, I keep thinking that a hardtail with a Monster would just be plain too much repeatedly on any hardtail. In this case I'm saying find a burlier frame if you want to keep using the Monster.
By the way, I give you heavy kudos for being quite sensible about this and not going on a rant like many others would and keeping your cool, everyone should be like this!
By the way, I give you heavy kudos for being quite sensible about this and not going on a rant like many others would and keeping your cool, everyone should be like this!