Joined: Jan 2010
Posts: 9,779
Likes: 1,746
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Could some sort of "device" be fed up the downtube through the bottom bracket opening?
I'm imagining a piece of tubing, cut in two, about an inch long, with a cone wedge in each end.
Connected to a brake cable housing with a cable attached so as to compress the split tube from both ends, thus expanding it in the vicinity of the dent.
One could feed the device in, slide it up the downtube, apply cable tension to slightly expend the tubing until resistance is felt to sliding the device past the dent.
Once positioned, additional cable tension would wedge apart the tubing, pushing the dent flush with the inside of the tube.
The wedge cones would need a steep enough angle so as to assure their release of expansion when cable tension was released (a stiff compression spring could also be used to push the wedges apart from the split tubing).