Vienna has 1600+ km of bike paths. Austria Open Data portal provides the dataset for bike path infrastructure in Vienna, Austria. I created a simple web app to show this on a map: https://blog.shoban.dev/visualizing-the-1600-kms-of-bike-path-in-vienna/

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Edit: thanks to u/Knusperwolf , More details about the paths

According to the official Website of Vienna, it's 1661 km. However, as mentioned here, this is what is included:

169.2 km of actual bike paths

170 km of mixes pedestrian/bike paths

44,6 km of bike lanes

142 km of multi-use lanes (like bike lanes, but less illegal for cars to drive on them...)

28.7 km of bike crossings and intersections

7.4 km of bicycle streets (where cars are allowed, but sometimes modal filters discourage driving cars there)

324.8 km of one way streets with a bike lane in the other direction

18.6 km of bus lanes that allow bikes there (and usually taxis, so it's pretty worthless)

275 km of bike routes (can be anything, but since these are not included in the other categories, it's simply quieter streets that cyclists are directed to using direction signs. Some of these actually do have a lot of traffic and are awful to cycle in)

8.9 km of pedestrian zones that allow cycling (but usually only "walking speed" which is not properly defined)

38.1 km of Wohnstraßen (google it, you are allowed to play football on the street, no through traffic for cars allowed, in reality those are parking lots)

358.8 km traffic calmed areas (honestly, no idea what that is. It probably contains "Begegnungszonen", which is a 20 km/h shared space, but we do not have 358.8 km of those)

73.9 km Mountainbike trails (mostly in the forest, you can see those in OP's map along the western edge