It's been 2 months since I started regularly wearing a hi-viz mesh safety vest on essentially all my rides.
In retrospect, the cost-to-benefit ratio is huge!!
It's a subjective thing, trying to determine how much of a difference it makes in actual safety. Up 'til yesterday, however, I'd only had one incident where I got the impression that a driver didn't see me. That was at a downtown intersection where I was on a thru street and the offender on a side street with a stop sign. She started out, then slammed on her brakes when she saw me at the last second. (Probably a combination of my looming, hi-viz presence and loud hollerin'. The driver was a little blue-hair lady in a big pearly-white Cadillac; she was probably too old to safely drive 10 years ago!)
I take comfort in looking down when I'm riding, and observing how VISIBLE that vest is! Even in the worst conditions... dawn and dusk... that bright color really stands out!
Yesterday, I was riding up Roosevelt Street - another "collector" with stop-sign side streets. Some airhead gal - late 20s or early 30s I'd guess, in a Subaru wagon with phone plastered to ear - pulled out from a stop sign, then jammed on her brakes mid-intersection when she saw (and heard) me. The vest is NOT a force field. But I am convinced that very few drivers will deliberately run into a cyclist. Anything I can do to avoid 'em telling the investigator, "I didn't see him!" is a good thing. I'm a believer! (Thanks, Bob T!)
An effective safety vest can be had for less than 10 bucks. What's that? 2 Starbucks? Just search for "hi-viz mesh vest" and shop away. (Or better yet, support a local merchant. I got mine at D&B; my friend at Boise Rigging Supply says they sell 'em, too.)
Oh - one other thing. A guy at the office is a big Oregon Ducks fan. One day he saw the vest and said, "Hey! You're wearing my school colors!" (Of course, pretty much EVERY color is an Oregon color...)