The riders will not take water bottles from fans - no telling what may be in the bottle.

Biggest help fans can provide and are allowed is cheering at a safe distance and providing newspaper to riders just before long, cold downhills.

Officials would likely turn a blind eye to mechanical help even if it is banned by the UCI/race organization. Of note, in the old days, racers were not even allowed mechanical help from their team; they had to carry their own spare tire and tubes, etc.