You can find walkable, safe neighborhoods all across the city, so it will likely come down to the location of your work, and the type of lifestyle you prefer (laid back, in the scene, family life, etc.). I live on the west side myself, so I'll speak to this area.
What is a Concave Wheel? Concave Technology takes the center of the wheel and dips inwards to give it that bowl effect. Rather than exaggerating a bigger lip for the back wheel, and a smaller lip for the front. Concave wheels emphasize the concavity of the rear wheel to differentiate from the front wheel.
The term concave is a term that defines the boundness of a curve or some geometric shape on a coordinate plane, now there is 2 types of concavity there is concave up or concave down, if its concave up it is bounded below and if it is concave down it is bounded above, howevere to answer your question no there is no such thing, however a trapezoid on ...