Blind spot mirrors for motorcycles are needed in an attempt to reduce the natural blind spots and increase safety.
The bike rider will have a natural field of view to the front and will be able to enhance this with occasional glimpses to the side. He may possibly risk the rare glance over the shoulder. However, as a rider, you will find that there are still areas to the rear or rear quarter which are not always in view. That is where the danger lies.
Other vehicles, especially other bikes, can easily hide in those blind spots. Bikes are especially vulnerable since one touch from another vehicle probably means a crash and serious injury to the rider.
Blind spot mirrors will increase the total area viewed by the rider in the normal riding position. They do this by either simply providing more mirror space, angled differently, or by offering a wider view in the same direction. A combination is also possible.
An extra mirror, mounted on a bracket holding it further from the bike than the original side mirror, will give the rider an extra view and provide them with a fuller picture of what is around them. A wider angled mirror on the existing mirror mounting might have the same effect.
With the side mirrors aimed at the back of the bike, the extra mirrors should be angled away to broaden the view. The rider should sit on the bike while it is stationary and ask someone to walk round it to check the adjustments. The rider should ensure the new mirrors’ field of vision overlaps that of the existing wing mirror. This makes sure there are no gaps for other vehicles to be lost in.
The result will certainly not be perfect, but blind spot mirrors should still be used.