Is this Dahon Classic III usable/salvagable?
02-28-16, 10:05 PM
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Is this Dahon Classic III usable/salvagable?
After browsing this forum for a few weeks, the idea of a folding bike gripped me enough that I suddenly (within span of about a week) found myself with three folding bikes, one new and two used. This post is about one of the used ones-- it's a Dahon Classic III.
At the time of purchase, I thought it was fine. The critical parts including brakes, 3-speed, and connector/hinges checked out ok. And I was quite fine with replacing the tires and administering a clean/lube. Today, however, upon looking closer there's a clear gap in the join between one of "V-arms" and the bar above. Since I don't know the technical terms, I've attached a picture (NOTE: The bike is upside-down in the picture, so please imagine right-side up for correct orientation), the gap is readily evident in the center of the photo.
Btw, sitting on the bike while stationary does not seem to have any effect on the gap (i.e. the frame/hinge are stiff enough not to apparently transfer weight to that "V arm") but that might not mean much when on the move.
It almost looks like I could jb-weld a metal shim to fill the gap and solve the problem. Anybody think that this might do the trick to use the bike safely?
TIA -- I'll be frequenting this forum a lot more now that there are 3 folding bikes in my garage!
At the time of purchase, I thought it was fine. The critical parts including brakes, 3-speed, and connector/hinges checked out ok. And I was quite fine with replacing the tires and administering a clean/lube. Today, however, upon looking closer there's a clear gap in the join between one of "V-arms" and the bar above. Since I don't know the technical terms, I've attached a picture (NOTE: The bike is upside-down in the picture, so please imagine right-side up for correct orientation), the gap is readily evident in the center of the photo.
Btw, sitting on the bike while stationary does not seem to have any effect on the gap (i.e. the frame/hinge are stiff enough not to apparently transfer weight to that "V arm") but that might not mean much when on the move.
It almost looks like I could jb-weld a metal shim to fill the gap and solve the problem. Anybody think that this might do the trick to use the bike safely?
TIA -- I'll be frequenting this forum a lot more now that there are 3 folding bikes in my garage!
02-28-16, 10:32 PM
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What does the bike feel like when you ride it?
That appears to be a cracked weld. And, little things like that often make big things. JB weld won't do anything.
If you clean (electric wire brush or sandblast) the frame spotless for about 1" on all sides of that crack, then a good welder should be able to weld that up in about 5 minutes. Then repaint, or leave it as a battle scar.
That appears to be a cracked weld. And, little things like that often make big things. JB weld won't do anything.
If you clean (electric wire brush or sandblast) the frame spotless for about 1" on all sides of that crack, then a good welder should be able to weld that up in about 5 minutes. Then repaint, or leave it as a battle scar.
02-28-16, 10:47 PM
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What does the bike feel like when you ride it?
That appears to be a cracked weld. And, little things like that often make big things. JB weld won't do anything.
If you clean (electric wire brush or sandblast) the frame spotless for about 1" on all sides of that crack, then a good welder should be able to weld that up in about 5 minutes. Then repaint, or leave it as a battle scar.
That appears to be a cracked weld. And, little things like that often make big things. JB weld won't do anything.
If you clean (electric wire brush or sandblast) the frame spotless for about 1" on all sides of that crack, then a good welder should be able to weld that up in about 5 minutes. Then repaint, or leave it as a battle scar.
You suggestion to re-weld is optimum but I was under the impression that it might be more economical to just buy another bike. :-) Unless welding such gaps is a trivial affair.
02-28-16, 11:05 PM
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Prepwork is key. It needs to be VERY CLEAN down to bare metal. The weld itself would be pretty trivial.
But, it is one of those things that if you can do it, or know someone who can do it, or somewhere you could do it, then it would be quick and easy once cleaned up. However, it could get expensive to pay shop time, but maybe not that bad if you can find someone to do it. TIG welding is often best for bike frames. Possibly fillet brazing too.
But, it is one of those things that if you can do it, or know someone who can do it, or somewhere you could do it, then it would be quick and easy once cleaned up. However, it could get expensive to pay shop time, but maybe not that bad if you can find someone to do it. TIG welding is often best for bike frames. Possibly fillet brazing too.
02-29-16, 09:44 AM
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I would just wire-wheel it clean in that area and lay down a generous sized brass fillet, using my oxyacetylene torch. A 10 minute or so job. Ask around. Maybe your friendly neighbor has a torch and is willing to help out? How about the high school welding teacher; it could be a good project for the class. Never hurts to ask your local framebuilder if you have one, the cost may be very reasonable. Clean it up with sandpaper in the area surrounding the crack, at least an inch in all directions, and try bringing it to a motorcycle or auto body shop. Its better than throwing the bike away. Shims/JBweld will do nothing for this issue; it has to be welded or brazed.
02-29-16, 05:33 PM
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I would just wire-wheel it clean in that area and lay down a generous sized brass fillet, using my oxyacetylene torch. A 10 minute or so job. Ask around. Maybe your friendly neighbor has a torch and is willing to help out? How about the high school welding teacher; it could be a good project for the class. Never hurts to ask your local framebuilder if you have one, the cost may be very reasonable. Clean it up with sandpaper in the area surrounding the crack, at least an inch in all directions, and try bringing it to a motorcycle or auto body shop. Its better than throwing the bike away. Shims/JBweld will do nothing for this issue; it has to be welded or brazed.
Prepwork is key. It needs to be VERY CLEAN down to bare metal. The weld itself would be pretty trivial.
But, it is one of those things that if you can do it, or know someone who can do it, or somewhere you could do it, then it would be quick and easy once cleaned up. However, it could get expensive to pay shop time, but maybe not that bad if you can find someone to do it. TIG welding is often best for bike frames. Possibly fillet brazing too.
But, it is one of those things that if you can do it, or know someone who can do it, or somewhere you could do it, then it would be quick and easy once cleaned up. However, it could get expensive to pay shop time, but maybe not that bad if you can find someone to do it. TIG welding is often best for bike frames. Possibly fillet brazing too.
Last edited by new_berlin; 02-29-16 at 05:38 PM.
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