I use them religiously on my bikes. 1.5" size seems small, but on my "normal" mirrors (anything you might find on a 70's-90's road bike) they do not obstruct the area of normal mirror significantly. Your eyes become used to where they are. I'll still do a head-check if there's enough traffic clearance, but if traffic is tight and you need to keep your eyes in front of you, they are lifesavers. Yes, cycle mirrors create blind spots.