Lasers? No one has ever heard of a plumb bob? SMH
Seriously, I put the bike in an old trainer and use a carpenters level against the wheels to make sure they are perpendicular to the floor. It's fairly easy to then drop a plumb bob from the stem to the tire and eyeball everything.
Or, just do like most people and take a hex wrench in your pocket for a couple rides and make adjustments till you're happy.
