Originally Posted by
Brad L
<snip> my framebuilder friend says I’d need to replace the downtube to remove the bosses. Of course, then I’d need to rechrome the head lugs.
That's serious overkill. I have filled H2O boss holes several times, it was easy and reliable. The tube inevitably has a weakened spot there from tempering, but no weaker than any other spot on a bike frame that got a braze-on. I silver-brazed in a plug and then filed/sanded it flush, but it can be done rapidly enough that only a little paint is ruined, possible to just respray that one area if concours-level paint isn't needed.
Your Piave is gorgeous and well worth that concours-level paint though, so I expect you would want whatever it takes to look perfect again. But I'd advise against rechroming, that is liable to do more damage than filling the holes would.
I made the plugs with a flanged cylindrical part sized to fit the hole, just long enough to reach through the tube wall and a little more (~1 mm) for an inside fillet of silver. The flange on top is just barely there, just big enough to prevent the plug from falling through. All the flange is filed off after brazing.
The brazing must be done by someone well-versed in thinwall bike tubing, not a muffler repair shop! The filing step is equally tricky because if the file tilts to one side or the other, it can nick the tube. This is the thin unbutted part of the tube, so any file marks are to be avoided. On such a fine frame, I would use only my finest files (fine here meaning opposite of coarse) and work slowly. I have seen fairly horrible coarse file marks left in frames from even hero brands like <redacted> or <redacted> (no need to name names here!), so don't assume a framebuilder is good enough at filing. Some might be skillful, but in too much of a hurry. You want someone slow for this job!
I am not angling to to do this repair, I am retired, all my framebuilding was more than 25 years ago.
Mark B