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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.

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Old 09-22-12, 03:50 PM   #1
goatalope
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Pre heat frame before cold setting?

I have a Surly frame (4130) with a pretty bad kink in the downtube. Its probably shot, but I'd like to try to bend it back. Does it make sense to heat the steel before cold setting? Not necessarily with a blow torch - I was thinking of using my heat gun which can easily get it hot to the touch, but not red hot by any means. Would that help?


I know the various risks and problems from reading other posts and previous experience.
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Old 09-22-12, 03:53 PM   #2
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if you don't get it hot enough, it will have no effect. If you do get it hot enough, you are likely to do more damage than not
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Old 09-22-12, 03:59 PM   #3
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Do not heat the frame, if you try to unkink it do it cold. The heat gun won't get the metal hot enough to cause any phase changes, not that you want to have that happen anyway. Can you post a shot or two? The beauty of 4130 is it's resiliency and toughness. If the frame's alignment is not damaged it might be best to leave things as is. Andy.
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Old 09-23-12, 01:21 PM   #4
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Does it make sense to heat the steel before cold setting?
nope, none..
all the brazing will re melt before the steel is hot enough to be in a plastic state.
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Old 09-23-12, 01:51 PM   #5
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It's not called "cold setting" for nothing.
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Old 09-23-12, 05:00 PM   #6
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Thanks for the advice. Here's some pictures. The head tube angle is pretty messed up, so I'm going to try to bend it back. I'll post results.
Attached Images
File Type: jpg Surly 1.jpg (96.2 KB, 41 views)
File Type: jpg Surly 2.jpg (101.2 KB, 45 views)
File Type: jpg Surly 3.jpg (89.9 KB, 37 views)
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Old 09-23-12, 08:23 PM   #7
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That frame is toast. Top tube is bent also. New frame time.
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Old 09-23-12, 08:27 PM   #8
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Thanks for the advice. Here's some pictures. The head tube angle is pretty messed up, so I'm going to try to bend it back. I'll post results.
Please tell us you're kidding.
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Old 09-24-12, 06:34 AM   #9
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Please tell us you're kidding.

Well, I'm not kidding about trying to bend it. I get that its bad. Never had a chance to bend out a frame. I just want to give it a try and see what happens. I'm curious.
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Old 09-26-12, 07:12 PM   #10
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Well, I'm not kidding about trying to bend it. I get that its bad. Never had a chance to bend out a frame. I just want to give it a try and see what happens. I'm curious.
Surely you jest !?!?

Go for it. It's not rideable or fixable, so it doesn't really matter.
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Old 09-27-12, 12:47 PM   #11
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One partial salvage idea that might be interesting for that frame, cut-off the DT and TT a couple inches from the BB and seat cluster and throw away the forward kinked section of the triangle. Have a framebuilder re-construct an new front triangle as a break-apart folding travle bike with couplers to join the old and new together.
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Old 10-03-12, 04:40 PM   #12
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A second option would be to straighten out the frame then add a patch over the dented/kinked area. Not a pretty solution and not one that I would do unless i was stranded in a situation that required the bike to be rideable.

I do agree that the dent is too kinked for further use without some further remedy. Andy.
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Old 10-03-12, 05:55 PM   #13
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just out of morbid curiosity....how did the frame get in that condition?
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