"White" or "black" only tells you how much of the visible spectrum will be reflected or absorbed. Less than half the heat from absorbed sunshine is in the form of visible light. The majority is infrared (IR) and a small fraction is UV.

A fabric that appears black but absorbs little IR may well be soaking up less energy than something that looks white but absorbs all IR. Google for "coldblack" fabrics about products that are based on this concept.

If you google the subject you may also come across mentions of a study on black clothes wore by Bedouin tribesmen in the Negev desert that showed little difference between how hot you feel in black or white clothes. One caveat with this is that Bedouin clothes are worn rather loose-fitting, allowing convection to carry away heat between the fabric and the wearer's body. Cyclewear on the other hand is usually quite tight-fitting. So this study may not translate very well into the cycling world.