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driving concerns

Ford's blind spot mirror has a convex spotter mirror aimed directly at the driver's blind spot.

I cut someone off today when I edged out of my lane to avoid a cyclist. The problem is that I didn't know the other car was there. I did a quick shoulder check but somehow still missed him. I'm driving a 2007 Honda Odyssey and I don't feel very confident about keeping track of what's in my blind spot in heavy traffic. Do you think those little stick-on convex mirrors are a good idea? – Tracey

You can overcome blind spots by adjusting your side mirrors so you can't see the sides of your vehicle, experts say.

"If somebody's driving with a blind spot, they need to adjust the mirrors properly so they're not looking at the side of the car – because you already know where that is," says Scott Wilson, Senior Policy Analyst with the Alberta Motor Association (AMA). "Rather than buying an additional mirror, adjust the mirrors so they're facing the adjacent lane."

The idea has been around at least since George Platzer, an engineer from Rochester Hills, Mich. wrote his 1995 technical paper "The Geometry of Automotive Rearview Mirrors - Why Blind Zones Exist and Strategies to Overcome Them."

Here's how to do it. Lean your head against the left window and adjust the left mirror so you just barely see the left side of your car. Then, lean to the right, to about the middle of your dash, and adjust the right mirror just until you can just barely see the right side.

If it's done properly, a car passing to your left or right should start to appear in your side view mirror just as it starts to move out of your rear view mirror. Platzer calls this the Blind Zone and Glare Elimination (BGE) setting. With it, the side mirrors show only the blind zones. There are still small blind zones left, but they're not big enough to hide a car, Platzer said.

"When driving with the BGE Setting, most drivers initially feel a sense of confusion with the outside mirrors; you are not sure where they are pointed; you miss not seeing the sides of the car; and you do not know how to interpret what you see," he wrote in a 1996 Society of Automotive Engineers (SAE) brochure on the topic. "Don't give up. The confusion will go away."

Platzer went on to develop a convex mirror now used by Ford and GM. But he told Globe Drive he still stands by the BGE setting, if it's done properly.

We tried it on a 2008 Honda Odyssey. It's a little tough to get used to, but it works.

As for stick-on convex mirrors, we didn't find much real information on them. Consumer Reports hasn't reviewed any. Amazon users give some a decent score – but there are complaints they fall off. There are also complaints that some are so small that drivers can't really make sense of what they're seeing, especially on the passenger side.

While developing his mirror, Platzer says he reviewed many of the stick on mirrors then available.

"I never really found any to be the answer to the blind zone problem," Platzer says. "Obviously, my preference for the blind zone problem is the mirror I developed."

Whether you use Platzer's setting or a convex mirror, the AMA and CAA still recommend old-fashioned shoulder checks.

"The only way you'll find out for sure if it's safe is to take a look," the AMA's Wilson says.

If you have questions about driving or car maintenance, please contact our experts at

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