From the very first kilometres, the fourth stage — 167.8 km from Arco to Trento, with 3,600 metres of elevation gain — presents itself as the queen stage of the 2026 edition. After just eight kilometres, the peloton faces the first-category KOM of Passo Bordala (14.8 km at 6.9%), with the initial sections up to Ronzo-Chienis shared with the Passo di Santa Barbara climb. A fast descent follows into the Adige Valley, after which the road rises again towards Vigolo Vattaro. A short, winding descent then leads into the Valsugana at the foot of Passo del Redebus — another first-category KOM (12.9 km at 6.8%).

The descent from Passo Redebus opens a 37-kilometre circuit consisting of a rolling section to Baselga di Piné, a steep descent, a flat segment, and another rolling approach to the Brusago climb, whose first three kilometres hold stubbornly in double digits. After completing the loop, the race heads for Trento for a technical, nervy finale featuring the climb to Povo — a decisive pivot in the 2021 European Championships. Ten kilometres remain from the summit to the line: first downhill, then flat into the heart of Trento.