Bent downtube?
#1
Senior Member
Thread Starter
Join Date: Feb 2004
Location: NC
Posts: 238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Bent downtube?
I found a 58cm Centurion lemans with tange 900 tubes at a thrift store. The bike is in very good shape ,wheels, fork , bars , no signs of a crash. I started to break it down for rebuild and found a bulge just behind the head tube lug on the underside of the downtube. It almost looks like it was made that way
maybe to tweak the geometry, or maybe the bike ran into a wall .But like I say all of the components are in great shape and the fork is not even scratched. Anyone seen a frame with a similar bend ?
maybe to tweak the geometry, or maybe the bike ran into a wall .But like I say all of the components are in great shape and the fork is not even scratched. Anyone seen a frame with a similar bend ?
#2
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
Yup. I suspect the bike has been run into a wall. How does the underside of the top tube look?
#4
Senior Member
Thread Starter
Join Date: Feb 2004
Location: NC
Posts: 238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I suspected that it was probably crashed, the tubes are otherwise straight and the drops are aligned. Maybe it was repaired. thanks for the info
#5
Senior Member
Join Date: Dec 2005
Location: Boulder, Colorado
Posts: 1,383
Bikes: Cinelli Supercoursa 69, Ritchey Breakaway Cross, Mondonico Diamond Extra 05, Coors Light Greg Lemond (built by Scapin) 88, Scapin MTB, Stumpjumper 83, Specialized Stumpjumper M4, Lemond Poprad 2001
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked 2 Times
in
1 Post
If there is a steel builder in your area they probably could replace the tube if you think the bike is worth it. Take a flash light (one of the bright LED with a small twist end) and a dentist mirror and check the area around the inside to check for cracking, excessive rust, or the lug pulling away from the tube. May be ok. A good LBS with knowledge of frame building would be a good source.
#6
Senior Member
I ran over a guy that had crashed in front of me in a race and had exactly the same frame damage. I rode the bike like that for quite a while. Very dangerous. Eventually the bulge will start a crack which eventually works its way around down tube. One day I was riding it and it felt really loose. Quick check, no flats, headset ok. Then I looked at the down tube and it was holding on by a thead! I was out about 20 miles and I called a friend to give me a ride home. Watch out!
#7
Senior Member
Thread Starter
Join Date: Feb 2004
Location: NC
Posts: 238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
At least the parts are worth something. Older Suntour components, Dia Compe aero brakes ,Araya wheels w/Suzue hubs. Not bad for $25.00.
#8
Senior Member
Originally Posted by San Rensho
I ran over a guy that had crashed in front of me in a race and had exactly the same frame damage. I rode the bike like that for quite a while. Very dangerous. Eventually the bulge will start a crack which eventually works its way around down tube. One day I was riding it and it felt really loose. Quick check, no flats, headset ok. Then I looked at the down tube and it was holding on by a thead! I was out about 20 miles and I called a friend to give me a ride home. Watch out!
#9
Senior Member
Join Date: May 2003
Location: Mountain Brook. AL
Posts: 4,002
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 303 Post(s)
Likes: 0
Liked 136 Times
in
104 Posts
Depends on the bulge. Steel has a yield limit and can bend some before it starts to give way. The yield limit could be exceeded by an attempt to straighten the frame.
If the frame is Al it should be discarded. Steel if not crazed or cracked might well last for sometime. It will start 'acting funny' when cracking begins, but once started the crack will propagate over a short time all the way around the tube, at which point the bike will be very squirrelly, not good at 25+ mph on curvy downhill. If usage is just short rides in non challenging circumstances it would probably be ok to use the frame.
Steve
If the frame is Al it should be discarded. Steel if not crazed or cracked might well last for sometime. It will start 'acting funny' when cracking begins, but once started the crack will propagate over a short time all the way around the tube, at which point the bike will be very squirrelly, not good at 25+ mph on curvy downhill. If usage is just short rides in non challenging circumstances it would probably be ok to use the frame.
Steve
#10
Senior Member
Originally Posted by Old Yeller
Was that a steel frame or aluminum? I wouldnt think a steel frame would be weakened that much to crack.
#11
Senior Curmudgeon
Join Date: Jan 2005
Location: Directly above the center of the earth
Posts: 3,856
Bikes: Varies by day
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 2 Times
in
1 Post
Steel will slowly tear - not crack. Aluminum, on the other hand, will crack and then fail catastrophically. When you see a tear starting in the steel, then it is time to retire the frame. Until that time, (and so long as the frame is straight) ride without worry.