Don't get me wrong because I love having decent mirrors in my vehicles, but I rely on them to give me a view of what is really behind me or coming up on me. I learned many years ago from a couple of near misses that nothing replaces shoulder-checking your blind spots. Long story, but I'll keep it short - many years ago I was riding on an interstate (think it was I-95) and had been riding for a number of miles in what I thought was open road. I was cruising along somewhat oblivious to everything because there wasn't a soul around me (or so I thought). I came up on a car in the right lane and decided to move over into the left lane. Shortly into the merge I heard a horn and corrected back into the right lane. I glanced over my shoulder to see a pickup truck off to the left-hand side of my rear tire. How long he had been there? I have no idea, but it must of been a long time. I felt like a complete idiot and had to stop at the next exit to take a break and calm down. I normally can't hear anything while riding - helmet and earplugs - but that morning I was darned lucky. I guess it just wasn't my time. From that point on, I have made it a habit to shoulder-check when changing lanes. I commute almost daily (35 miles each way) and just this year there have been three close calls during rush hour traffic where people have abruptly come into my lane. I don't believe that any of them checked their blind spots and I was lucky and had escape lanes to move into. I normally try to go into the office early to avoid rush hour traffic, but each of these were peak rush hour when I was running late. Because I was running late, I was riding a little more aggressively than I normally do during my commute. I was passing cars in the faster moving lane and I normally just cruise and take is easy riding to the office and try to keep my head on a swivel.
For what it is worth, my advice is to always shoulder-check because the consequences of not noticing someone off your rear tire could really ruin your day or worse.
2006 Caspian Blue Triumph Sprint ST
2008 Blue and White Aprilia Tuono
2009 Jet Black Triumph Street Triple
2006 Kawasaki Vulcan Mean Streak (not bad for a cruiser)
Dress for the wreck, not the ride.....