Bike Forums

Bike Forums (http://www.bikeforums.net/forum.php)
-   Framebuilders (http://www.bikeforums.net/framebuilders/)
-   -   Frame repair question on steel frame (http://www.bikeforums.net/framebuilders/672802-frame-repair-question-steel-frame.html)

t4mv 08-18-10 02:11 PM

Frame repair question on steel frame
 
'Sorry if this is the wrong forum, but it was the closest that seemed to qualify..

If a down tube and top tube needed to be replaced, what is the likelihood the head tube and head lugs would also need to be replaced? Does the answer vary if it's brass vs. silver, or is it simply a question of heat? Thanks for any thoughts and feedback.

unterhausen 08-18-10 05:30 PM

personally, I would just reuse the lugs. I doubt the lugs would need to be replaced, they should be weldable if they are broken. A lot of people would remove the top/down tubes and reuse the head tube.

I would ream the head tube out on my lathe. Just seems pointless to save the head tube to me.

t4mv 08-18-10 07:31 PM

Quote:

Originally Posted by unterhausen (Post 11312877)

I would ream the head tube out on my lathe. Just seems pointless to save the head tube to me.

Yes, this would be true; the real question revolved around whether the lugs could/would be saved vs. heat from removing the damaged tubes rendering the lugs useless. I don't have enough experience with this to know whether a choice to go fillet brazed is due to dead lugs or lack of desire (to replace w/ new lugs). Thanks very much for your thoughts.

NoReg 08-18-10 09:53 PM

What is the assumption here, is it that the two tubes got dinged, but everything else is OK, other than being connected to junk main tubes. Seems like you aren't going to be able to ream out all the tubes, so you are going to need to depend on heating them off. Since lugs are mostly just plain steel, nothing fancy, there isn't much one can do short of lighting them on fire that will render them useless, but it can take impressive amounts of heat to get them off. Not a lugs guy, but it seems like you would end up building a lot of the bike backwards, while having super heated clusters that are not all going to be rebuilt. Sounds like fun.

t4mv 08-19-10 12:19 AM

Quote:

Originally Posted by Peterpan1 (Post 11314533)
Not a lugs guy, but it seems like you would end up building a lot of the bike backwards, while having super heated clusters that are not all going to be rebuilt. Sounds like fun.

Correct, front half of frame is going to end up rebuilt, consisting of new TT, DT and HT. Seat cluster is hanging around, and BB shell is hanging around, but HT lugs (the original ones) went bye-bye, to be replaced with fillet brazed joints. I'm just curious as to whether the choice to go fillet on a lugged frame is done out of necessity, or if the guy just doesn't want to do it. I know what the guy's side of the story is, I'm just trying to get a second opinion. ;)

unterhausen 08-19-10 12:27 AM

replacing with fillet is a lot less time than trying to recover the lugs. I've never done this on a customer's bike, but I've done it on some for myself. I've successfully un-brazed lugs, and I've gotten ahead of myself and ripped lugs because I didn't get enough heat into them. I have a small aircraft style torch, and takes a huge amount of patience to heat up a large mass all at once like you need to do to get a whole joint up to temp. There is a video out there of a Ciocc being repaired, and the amount of heat going into that head tube is just astounding. There is also a photo sequence on the Yellow Jersey site about this kind of repair.


All times are GMT -6. The time now is 11:55 AM.