I bought a 1020 Specialized Tricross a while back and a recent bike store visit mentioned I am a 5' 7" guy riding with 38mm handle bars. They said I should at least be a 40mm or a 42mm. They said I would breathe better as my chest cavity would expand with a wider arm stance, but the minor negative is there would be less aero dynamics. So I guess I need to replace my handle bars with a Specialized 40mm bar.. So I thought I would ask here in this forum your opinions. Thanks.