Thats just surface rust which from the photos, does not look like it affects the structural integrity at all. I don't think theres any other fix than to sandblast and repaint. It looks like its a bad paint prep job that is making the paint flake off.
__________________
Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1