This relates to 'overshoes' and plain 'white oversocks' being banned at the recent National Championships.
from uci webpage
1.3.033 It shall be forbidden to wear non-essential items of clothing or items designed toreduce air resistance.
During road and mountain bike races, clothes and over-garments may be essentialitems insofar as weather conditions suggest this. In this case, the nature and texture of the apparel must be clearly and solely justified by the need to protect the rider from bad weather conditions. The judgment is left to the race commissaires.
Cycling riddled with cheats and the UCI come up with this...Well done! A leap forward for our sport and proof that international governing organisations aren't just a bunch of old men sitting round drinking Schnapps and checking bank accounts and sponsors deposits in them! Has Sepp Blatter taken up residence at the UCI?