Originally Posted by
grumpus
It's unlikely a simple sleeve will work, as the fracture is probably where the butt ends, so you'll be working with two different internal diameters. Also you'd want to silver solder it, and it won't be easy to get the inside of the tubes as clean as you need for that to work reliably. It's not difficult for a competent frame builder to replace the whole tube, but if the downtube is corroded or fatigued the top tube may not be far behind, and if you replace both of those you're paying for half a frame anyway so you might as well get a new one.
I'd have to say I agree that a sleeve is not the appropriate repair in this instance. A full tube replacement is warranted. And yes, it is not as easy as it sounds. If it is repaired, the frame builder may be able to determine what happened exactly and whether any other tubes are in jeopardy of failing.
There is also the issue of liability to consider. I don't know that frame builders carry liability insurance, but they should!
As much as I like to save and/or repurpose things, I'd be looking for a new frame. If you miss sitting on the bike seat, turn it into a stool as suggested above. They are actually pretty cute.