The road rises from the start, although at shallow gradients. After a descent, the first official climb kicks off at kilometre 35. It’s gentle warm-up of 9.7 kilometres at 3.8%.
A relatively calm phase follows before the riders enter the centre of the race, with four uphills packed into just 36.6 kilometres. The climbs 2.9 kilometres at 7.3%, 2 kilometres at 4.3%, 2.6 kilometres at 6.5%, and 3.4 kilometres at 7.6%. More than 70 kilometres remain at the summit of the last one.
The section starts with a descent, followed by roughly 50 kilometres of relative calm. The only ones paying close attention at this point will be those eyeing the KOM jersey, as the Milloi climb — 3.5 kilometres at 4% — features in this segment. For everyone else, all focus is on the main challenge of the day: the Izua.
The Izua is not only the final and toughest climb of the day, it’s also the most well-known. It largely overlaps with the often-used summit finish to the Arrate Sanctuary. However, instead of heading straight to the Sanctuary, the riders will now turn left. This version of the climb measures 3.5 kilometres at a brutal 10.6% average gradient. The steepest section, which kicks in after 2.5 kilometres, ramps up to an eye-watering 13.4% over the next 2 kilometres.
Last year, the Tour of the Basque Country was decided on the Izua. Juan Ayuso and Carlos Rodríguez crested the summit together before rolling to the finish side by side — Ayuso securing the overall win and Rodríguez taking the stage victory. This time, however, the finish line is much closer. From the top of the Izua, it’s just 11 kilometres to Markina-Xemein.
The first half of this run-in is a proper descent, while the second is more of a gradual downhill false flat.
The first three riders across the line pick up 10, 6, and 4 bonus seconds, while the intermediate sprints come with 3, 2, and 1 seconds.
Ride the route yourself? Download GPX stage 4 2025 Itzulia Basque Country.
The 4th stage of the Tour of the Basque Country starts at 13:03 and the race is expected to finish around – both are local times (CET). See the timings in the slideshow below for details
Tour of the Basque Country 2025 stage 4: route, profile, more
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