The Karlsruhe straight line challenge is carried out by cycling as close as possible along one of the city's radiating lines, starting from the palace tower, until reaching a natural end.

The city [Karlsruhe] was planned with the palace tower (Schloss) at the center and 32 streets radiating out from it like the spokes of a wheel, or the ribs of a folding fan, so that one nickname for Karlsruhe in German is the "fan city" (Fächerstadt).

What mainly differentiates this from the "straight line missions" you might have heard of, is that you don't get to choose where the line runs! This challenge is entirely within the spirit of spontanous "go for it and see what happens" adventures (which is one area I personally get my kicks from). This means that there is effectively zero planning, and you just get on a bike and go... along the closest street/path/surface you deem suitable. How many meters you deviate isn't really what's relevant.

Here's a simple map of all available lines:

I recommend the Organic Maps app for your phone, which is the perfect tool for guiding you. If you're fancy you can even trace out a rough route beforehand, and then load it into the app. I've found it to be a bit annoying having to constantly stop to "live-plan" the route.

My personal adventures (contains spoilers!)§

I hope to update this list as I continue doing these. Because I still don't own a bike, and I'm a bit crazy, I did all of these using bike sharing bikes from KVV.nextbike (I'm sorry for getting them dirty!). Yet this does have the nice side effect that I can just leave the bike in a participating city, and ride the train home without it!

The northern "Via Triumphalis" line§

Attempted 2025-06-28. This one starts out very easy, as you follow along a purpose-built bike path for the first ~9km. You're conveniently spit out at the B36/L559 intersection near Leopoldshafen, after which you're on your own. Trekking through various bicycle-unfriendly fields, the line will perfectly lead you over a railroad-crossing of the AVG branch line to KIT Campus Nord. The remainder of the route will have you navigating various towns, farmland, as well as a cut-off meander of the river Rhine. There's some pretty ugly offroad sections. The "natural end" here is a a nice camping/lookout spot at the Rhine.

the AVG crossingnextbike at night

The "Waldstraße" line§

Attempted 2025-09-06. This has you leave Karlsruhe through ZKM/HfG, following Tram 4 to Oberreut, after which you will encounter a glider airstrip, and the Epplesee lake. Durmersheim will have you go right through a schoolyard, and lead you right into a fair bit of forestry. After Steinmauern there's a pretty well placed bridge over the Murg river, followed by a bunch of more countryside. If you spot an old boat floating in the water (the "Aalschokker Heini"), you've also pretty much reached the old Rhine bridge near Wintersdorf. That bridge is placed dead-center on the line, which is an invitation to keep going to France, but I decided to call quits here.

map showing GPS recording

nextbike on schoolyardthe "Aalschokker Heini"Wintersdorf bridge

Final words§

If you're mad enough to try one of these on your own, please don't hesitate to tell me about it!!! friz64.de