Customer Reviews

Bicycle Accident Reconstruction for the Forensic Engineer

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I will only detail the major problems with chapter 16 (pp. 123 through 131), which are representative of the kind of things I don't like about the book.

The author uses several different symbols for the same thing (e.g., C and Cg for the center of gravity) and uses undefined symbols (e.g., all symbols when he uses conservation of momentum to derive a speed). BTW, he does not bother to tell the reader that he is using conservation of angular momentum as opposed to the more common linear momentum. Furthermore, he uses symbols in text where such use serves to save a few keystrokes and to confuse the reader (e.g., "the direction the C travels under various conditions").

The chapter contains two "Figure 1", neither of which has properties claimed by the author (see next paragraph).

There are incomplete and grammatically incorrect and, thus, confusing sentences (e.g., "An examination of Figure 1 reveals that an arc is drawn around This represents a cyclist rotating around the handlebars when enough to allow the Cg to rotate around the handlebars." on page 124). To add insult to injury, (the second) Figure 1 contains no arcs other than the ones representing the bicycle wheels.

The author appears to not know the difference between mass and weight (bottom of page 125) and to not know how to convert between the two (calculation on top of page 126).

On pp. 125-128, he states repeatedly that the symbol M stands for the weight of the rider. Since the weight of a bicycle is somewhere between 10 and 50 pounds (I'm no bicyclist, so this estimate may be unnecessarily coarse) and the weight of a rider is around 130 to 200 punds, there needs to be a justification for ignoring the weight of the bicycle.

The second Figure 1 is not legible; one can make out the drawing but the text cannot be read.

"Since the force applied must go from zero to 250 pounds, it should be averaged by dividing by 2." This is valid only if the increase from zero to 250 punds is linear. The author does not justify -- or even mention -- that the increase is, in fact, linear.

In the author's use of angular momentum (pp. 126-8), he does not mention what the symbols mean. This lack makes it impossible to verify that his derivation is correct and that his approximations are reasonable.

Should the author want me to detail all my complaints about the book, he can contact me at peterbergh@wildblue.net.

Mr. Green is a seriously qualified engineer and his book is well written and very specific in illuminating this intriguing subject.He may be the best forensic engineer in the country for this topic.