Originally Posted by
AnkleWork
If more brute strength is required, tapping the frame to a larger bolt size is an option. In any case a straight force-path is best.
...if this were me, and I was experiencing this problem, I would probably try this first. I would also probably through bolt the larger replacement, and nut it on the inside of the dropout, if possible. If I could find a bolt I could adapt so that the part going through the dropout was not threaded, but only the end where I nutted it was, I would do that, too. Finally, I might spooge in some kind of anti-seize in the hope that the sacrificial metals in it might preserve my bolt for longer service.
Doing all this will require some fiddling, but you're gonna have to fiddle with it to drill out that bolt remainder anyway.