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

damaged steel frame

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.

damaged steel frame

Old 03-28-11, 10:18 PM
The Loneliest Domestique
Thread Starter
bad_mojo's Avatar
Join Date: Aug 2007
Location: St. Louis, MO
Posts: 111
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
damaged steel frame

A friend of mine has an old steel tandem and the top of the seat tube broke. He's convinced that simply welding it back together would work. I haven't really worked on frames, but the break doesn't seem very clean and looks like it would be very hard to fix. Are thoughts/suggestions? Thanks.

Attached Images
File Type: jpg
seat lug.jpg (51.2 KB, 30 views)
File Type: jpg
lug1.jpg (34.0 KB, 23 views)
bad_mojo is offline  
Old 03-30-11, 09:49 PM
Old fart
JohnDThompson's Avatar
Join Date: Nov 2004
Location: Appleton WI
Posts: 21,719

Bikes: Several, mostly not name brands.

Mentioned: 126 Post(s)
Tagged: 0 Thread(s)
Quoted: 2243 Post(s)
Liked 637 Times in 428 Posts
Where is it broken? If it is above the lug or seat tube clamp it may be amenable to welding.
JohnDThompson is offline  
Old 04-01-11, 03:39 PM
Senior Member
pyeyo's Avatar
Join Date: Feb 2007
Location: dead center of Washington State
Posts: 92

Bikes: how big is this cell anyway?

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times in 1 Post
A little tough to see whats what, but welding what's there is going to work even if you did join it or cut it clean and butt something you will have to ream the seat pin again and it will probably last a short time. It looks like the seat tube passes throught the top tube. You could slip another tube internally butting it and use a smaller diameter post but the best thing is to replace the entire seat tube going oversize to make up for material lost getting the old tube out. Good luck.
pyeyo is offline  
Old 04-01-11, 08:52 PM
Six jours
Senior Member
Join Date: Mar 2007
Posts: 6,401
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
I'm not sure what I'm looking at either, but it appears to me (FWIW) that operator error is at fault here. The only way I can see this kind of failure is if there was only an inch or so of seat post inserted into the tube.

Regardless, if I was tasked with fixing the frame I'd clean up the top of the damaged seat tube and braze in another section of tube on top of it, with a reinforcing ring around the break. Then I'd be damned sure to insert the seatpost several inches into the tube from then on.

The simplest fix, FWIW, is just to get a seatpost with an internal expander. Then you just have to clean up the ragged edges of the break and call it a day.
Six jours is offline  
Related Topics
Thread Starter
Last Post
North Coast Joe
Bicycle Mechanics
02-04-13 10:59 PM
Bicycle Mechanics
09-27-12 04:24 AM
Mountain Biking
02-24-12 09:02 AM
06-12-11 06:53 PM
11-01-10 02:03 PM

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 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.