I have a science degree that involves anatomical physiology and human biology, and I can tell you that black penises are typically no larger than white when erect. The false belief that they are is because the sacs in the penis that hold blood have less elasticity in a black penis than a white, so they are only larger when flaccid. Of course, this is in MOST cases, not all. Women usually want more girth than length anyway. That is where Asian men are very deficient.
So ... the one difference in penis size is with Asian men, whose penises average about 4" - 4.5" in length and seriously lacking in girth when erect. However, most full-blooded Asians have smaller bodies in general, including the women, whose vaginas are much smaller and tighter, as well, to accommodate the smaller dick size.
In summation, two things: 1. Women need to stop thinking that black cocks are bigger. They, generally, are not! And 2. Those who win out the most are white or black guys who get to hook up with Asian women and their tiny, little pussies.
Have an awesome day, dudes!