About Zagreb Trail race:
The start and the finish line of the race is in the very centre of Zagreb, only 300 meters from the main square. Competitors can participate in three types of races: Ultra, Challenger and Active. Zagreb Trail also consists of a civil race which is 7km long. The track mostly goes through forest trails and only has about 30% of paved roads for short distances.
zagreb trail via vacations

The official lenght of the races – GPS taken from the Trecking league:

Ultra: 45.8km i 2300m of the total climb
Zagreb Trail ultra GPS trail

Challenger: 21.3km i 860m of the total climb
Zagreb Trail ultra GPS trail

Active: 13.4km i 400m of the total climb
Zagreb Trail ultra GPS trail

Light (Civil race): 7km i 200m of the total climb
Zagreb Trail ultra GPS trail

zagreb trail map via vacations

Background Zagreb Trail race:
The combination of dirt roads, trails and about 30% of paved roads. Road running shoes are enough during dry days, while trail running shoes are better suited during rainy days.
For the first 1500m is a forest trail with short road crossing where there are volunteers that keep the traffic closed. After that follows 300m of paved road and then the forest trail again for 3.3km with short 100m long road parts. The asphalt is on 5300m to 6300m part of the race. The next 32km is a forest trail with short crossings over roads. After that, the next 1.2km is an asphalt road, then 1300m of meadow trail. The next 2.1km is asphalt, then comes a single track forest trail, crossing the road and going down the meadow, at the end of the meadow, on 44th km, starts a footpath, hard gravel road, the footpath lasts for about 3km until the finish line.
Other categories have more of the paved roads because they are shorter and go less through the forest.

Personal experience Zagreb Trail race:
Year 2015, the race took place under constant rain and the whole trail was completely muddy, on some parts it was possible to even „ski “on the mud. All in all, a perfect experience.
Year 2016, the race took place on a hot and sunny day, running through the forest was refreshing, while running on the road was extremely hot due to the warmed up asphalt. It was more fatiguing then last year.

You might also find the following links useful:

Croatian Trekk and Trail league – the following races registration