A lot of times guys use equipment that is not supplied by official team sponsors. For example in this year's tour Froome was using a set of unbranded wheels in the mountains. It was rumored that they were AX Lightness but never confirmed. Froome and Wiggo also use Osymetric Rings (non standard team issue), as such the logos are removed/covered over.

BMW is the real deal in pro cycling and (not speaking for him) used a set of wheels that he felt was going to give him an advantage.

Help a good guy out and buy this set of wheels (plus he's a little dude so the wheels would have not really been stressed ;)).