The makers of the bike probably primed and painted it with the ideal stuff at the ideal moment in the ideal conditions. Why would you want to take that off and chance that you know what the correct primer or paint is to bond to that frame material? As much will you have the ideal conditions?

I'd just sand down what ever paint is loose and feather back to good adhering paint any chipped or flaking edges. At most I might sand till I remove any finish that isn't original.

Sanding really doesn't take long on a bicycle once you get going.