Originally Posted by
dddd
Using cable and housing to both actuate the device and to act as a handle for getting it into the right spot along the tube, no problem with having to turn any bolt.
As for the vent hole in the seat tube, it could be all but cut away to the full ID of the top tube (using a ball stone on a die grinder, or perhaps a Dremel or a cylinder/head porting tool), allowing some sort of cable-operated device to feed in.
I designed in my head a slim leverage device for this purpose, no cones to wedge, just a pair of brake cable-operated lever arms with mandrels attached, making for entry into a relatively small hole, at an angle, from the seat tube opening.
I have a mint, original, silver-black 1975 Raleigh Pro with a small TT dent, and a 1984 Trek 520 with a bigger dent. Both could be fixed without messing up the paint.
Ah, I see what you mean with the cable and housing. Basically just have a brake lever attached to the end and squeeze hard. Cool idea. something like this:
It would be important that the places where the levers actually push against the tubes not too thin and pointy. I see a problem in that these things need something to push against, and might end up causing a bulge if the area isn't reinforced externally with blocks, or if the contact points are too small. Although any bulge that did happen inadvertently would be a lot easier to fix than the dent that would have just been fixed.
I find myself suddenly in the weird position of wishing I had a frame with a dent in it. I don't think I currently have one.