Stage 4

Thursday April 08 2021 - Gasteiz to Hondarribia - 189.2 km Hilly
 

This is the longest stage of the Itzulia. There will in effect be two races: one for the overall race leaders over the last 50 km, where there is room to do some damage and a break from the top of Erlaitz could enable a rider to reach the finish alone; and another for breakaway riders, who will have a chance to make it to the finish depending on how far in front they are when they reach the final climb (Erlaitz).