Previously, U23 men on year-long contracts with WorldTour teams were excluded from racing the U23 category in the Worlds road race and time trials.
Under the new rules, U23 men on WorldTour teams may race the U23 category provided they have not raced in the elite men's field at a previous road world championship.
The move opens the door for riders like Caleb Ewan, who have been in the WorldTour but not been selected for elite Worlds to compete as an U23 in 2016.
The UCI also added a women's U23 category for cyclo-cross. The women's U23 field will consist of riders aged 17-22.*
While the UCI added a new World Ranking for elite and U23 men, it has not yet revised the rules for allocations for the World Championships, which are currently dependent upon the WorldTour nations rankings.
The UCI confirmed that the rules regarding allocations for the 2016 Olympic Games will not be altered.
The qualification system can be found here.
*Corrects previous version that indicated women U23 was for road.