Trucks are extremely dangerous for cyclists and in many of the fatal crashes involving a bicyclist and a truck, the cyclist is first hit by the side of the truck, slides under it and gets crushed under the wheels. Such crashes happen most of the time when the truck is making a right-hand turn in front of the bike. It is called the Right Hook. Because of the large dead angles, the truck driver often doesn’t see the cyclist riding on its side and the cyclist realized too late that the truck is turning right.
The installation of side guards on trucks is so far the best way to prevent bicyclists and pedestrians from falling under the wheels if they are hit by a truck. So far a few cities including New York have passed legislation to require the use of truck side guards but the approach is piecemeal and bicycle advocates are calling for federal action. Read more in Fair Warning