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.
In mathematics, concave function and convex function play an important role. Both the functions are related to each other. A concave function is the negative of a convex function. A function $f(x)$ is concave over a convex set if the function: $f(x)$ is a convex function over the set. Then, the result obtained for convex functions can be modified into result for concave functions by multiplication by -1 and vice versa.