Go Back  Bike Forums > Bike Forums > Framebuilders
Reload this Page >

Chinese Trek welding

Notices
Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

Chinese Trek welding

Old 03-27-22, 10:07 AM
  #1  
guy153
Senior Member
Thread Starter
 
Join Date: Dec 2019
Posts: 788
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 276 Post(s)
Liked 197 Times in 164 Posts
Chinese Trek welding

Having made a new frame and fork for my Trek 520 Tourer (actually few components are original to the Trek anyway) I thought I'd have a closer look at the welds on the old one. None of this is "dangerous" or anything in my opinion and I think the bike is fine (I rode it for only a few years, as it was a warranty replacement for an earlier 520 I owned, made in USA, on which the frame actually broke) but it's interesting to see now that I have more of an "eye" for TIG welds.

First the frame and fork next to the new ones:



And now some of the interesting features on the Chinese one. Exhibit A, this looks like the TT burned back and our welder had to fill in a bit of a hole:



Exhibit B. This is underneath the DT (where the original USA-made frame failed actually). You can see that the weld has actually been filed down. I wonder what horror show this was "fixing":



Exhibit C, a little bit of undercut on the side of the DT:


Exhibit D. Possibly the ST burned back a bit here. Or it may be just that a sudden loud noise caused our welder to let the TIG torch stray a bit:


Exhibit E, the inside the SS where they join to the dropouts. Just a bit ugly is all:


Exhibit F, undercut on the fork:


And finally, the underside of the fork. What's happened here is the bottom of the sleeve has melted into the weld. It would be better to weld first, with a bit more overhang, and then run a hole-saw through for that curved effect that people like (I actually don't mitre the bottom of the steerer at all and put a cap on it, for better or worse):

guy153 is offline  
Likes For guy153:
Old 03-27-22, 12:58 PM
  #2  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 16,251

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3420 Post(s)
Liked 2,110 Times in 1,379 Posts
I agree that with our better trained eyes we can see joining (or forming too) "issues" that most don't even look for. I suspect a Trek rep might say that the frame hadn't broken is proof of how well the frame is made, regardless of the looks. Andy
__________________
AndrewRStewart
Andrew R Stewart is online now  
Likes For Andrew R Stewart:
Old 03-27-22, 01:57 PM
  #3  
guy153
Senior Member
Thread Starter
 
Join Date: Dec 2019
Posts: 788
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 276 Post(s)
Liked 197 Times in 164 Posts
Yes I would call this good enough. I don't think any of these issues would cause an actual failure any time soon. Someone paying top dollar for a custom frame would expect better but as you say most people would never even notice.
guy153 is offline  
Old 03-28-22, 04:39 AM
  #4  
pwyg
Senior Member
 
Join Date: May 2013
Posts: 55
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Likes: 0
Liked 6 Times in 5 Posts
It is production welding, i have seen the same thing on custom built frames and many production frames including Bridgestones. Quality control is a time based and therefore a factor in the final cost if the product. Therefore you see a lot of this. Paint choice can also hide a lot too, this is why powder coating is great as it is heavier on average when compared to wet paint. But then I have stripped a cycle art painted frame that had an unbelievably thick primer/filler layer under the paint. There is a lot to the term what you see and do not see. Since frames are painted your assumptions of quality is based on that aspect of the frame not the actual important bits that natter more. Since I an of an earlier generation of cyclists and the same for my indoctrination in to building regardless of the appearance of a Tig joint I view it negatively, since the nature of Tig is a shortcut joining process.
pwyg is online now  
Likes For pwyg:
Old 04-06-22, 09:12 AM
  #5  
guy153
Senior Member
Thread Starter
 
Join Date: Dec 2019
Posts: 788
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 276 Post(s)
Liked 197 Times in 164 Posts
Update to this. I just measured the alignment. The string goes from the dropouts around the HT in the usual way. The gap from ST to string is 4.5mm larger on one side than the other! These calipers are set to measure the gap on the other side so they should just touch the string on this side. I never noticed this when riding it of course but it's still pretty awful.


guy153 is offline  
Likes For guy153:
Old 04-06-22, 07:11 PM
  #6  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 16,251

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3420 Post(s)
Liked 2,110 Times in 1,379 Posts
Many bike brands are very nebulous about alignment tolerances. For good reason as the common production bike frame hasn't had much time allowed for regarding its alignment. As bikes have become more a commodity then a trades product this should be of little surprise. Andy
__________________
AndrewRStewart
Andrew R Stewart is online now  
Old 04-06-22, 07:53 PM
  #7  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 22,590
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 2,146 Times in 1,530 Posts
My lbs said that trek told them they wouldn't warranty something that was within 5mm. If a frame fails the string test by 4.5mm, that means it's only off less than 2.5mm from centerline. So that's within tolerance. Now imagine that if it was off 9.5mm and being told it's within tolerance.
unterhausen is offline  
Likes For unterhausen:
Old 04-07-22, 12:46 AM
  #8  
guy153
Senior Member
Thread Starter
 
Join Date: Dec 2019
Posts: 788
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 276 Post(s)
Liked 197 Times in 164 Posts
The part I don't understand is that in my experience, with 6 TIG frames in a row now, is that if my jigging is right to start with then things hardly move during welding. Certainly nothing like that far. And in the case of this Trek, the HT and ST are still in parallel planes (which is what matters much more). If the cause were welding distortion then it would be all over the place. So the most likely cause is just poor jigging. But you would think that in a production environment the easiest part would be to give everyone a decent jig where you just throw the tubes in and they're automatically in the right places.
guy153 is offline  
Old 04-07-22, 07:39 AM
  #9  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 16,251

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3420 Post(s)
Liked 2,110 Times in 1,379 Posts
Originally Posted by guy153 View Post
The part I don't understand is that in my experience, with 6 TIG frames in a row now, is that if my jigging is right to start with then things hardly move during welding. Certainly nothing like that far. And in the case of this Trek, the HT and ST are still in parallel planes (which is what matters much more). If the cause were welding distortion then it would be all over the place. So the most likely cause is just poor jigging. But you would think that in a production environment the easiest part would be to give everyone a decent jig where you just throw the tubes in and they're automatically in the right places.
I think there are some assumptions said that are not as true as often as you think. From the jig tooling condition, the amount a frame can move with welding and the motivations/skills (beyond laying a bead) of the workers. Having seen a number of vids taken in Asia factories (and presumably showing only what the company wanted to show, their best practices I would think...) there are a number of scenes where I take issues with methods. Andy
__________________
AndrewRStewart
Andrew R Stewart is online now  
Likes For Andrew R Stewart:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.