Frame material doesn't affect comfort. The extremely stable diamond shape of the frame makes all material differences go away. Where material matters is the sea

Frame material doesn't affect comfort. The extremely stable diamond shape of the frame makes all material differences go away. Where material matters is the seat post (I think carbon has the most flex though and should be most comfortable). My racing bike is steel by the way. Not because of comfort, but because it's pretty beautiful handcrafted in Italy with cromo velato.