After a good running season, I thought I’d use my marathon fitness and give the Ringbahn/Berlin Train Loop FKT a try. This is a cool way to see the city, though parts of the route are not all that scenic and "nicht gerade vergnügungssteuerpflichtig" (not necessarily subject to an amusement tax).
Elapsed: 3:23:45 (4:48/km; 7:43/mi)
Moving: 3:05:44 (4:23/km; 7:03/mi)
Report: I set out solo at S Prenzlauer Allee at 10:30 on a sunny fall Saturday, heading counterclockwise. The northern part of the route is easy enough, zipping past Gesundbrunnen and through the Westhafen industrial area without a problem (though others folks have had issues here). After some kilometers in Moabit, I ran through the leafy Charlottenburg Schlosspark, which is a nice break from the grey roads and warehouse areas you'll spend a lot of the route running through. Next, I headed south through Charlottenburg/Halensee/Wilmersdorf, then cut back eastward. My favorite discovery of the entire route is the cute 1.5-story Fachwerkhäuschen/timber-framed house from 1909 at Perelsplatz in Friedenau/by S Bundesplatz, which looks like it might be made of gingerbread and/or you will have to answer some riddles before being let in. Next, I passed Innsbrucker Platz, crossing over the Berlin Marathon course's distinct blue line on the road. The area around Südkreuz is up next, with a lot of car traffic and time spent waiting at traffic lights. Fortunately, this is followed by the smoothest running of the route, 2.5km on Tempelhofer Feld, by far my favorite running spot in town and a nice familiar path after a lot of time spent navigating through obscure areas (bridges under Bundesstraßen, Industriegebiete, residential areas). You can make up a few minutes you lost at traffic lights here. Next, I zipped further eastward through Neukölln before heading back north, crossing through the Treptower Park station past Rummelsburg and into Friedrichshain. This was about 35km into the run and I was beginning to feel my legs. Fortunately, once you're past S Frankfurter Allee, it's pretty smooth sailing, right by the train tracks and down the fairly long and broad Storkower Straße, which crosses Landsberger Allee (formerly Leninallee), turns into Grellstraße, and takes you all the way back home to S Prenzlauer Straße, right where you started.
Some thoughts for future Ringbahn runners: You'll want to wear shoes with some stability, a lot of this is cobblestones and not smoothly paved. Scout the route by bike beforehand if you can: this goes through some obscure areas and there is always plenty of construction going on, which could throw you off. It's probably best to run early in the morning – unsurprisingly, this has a lot of traffic lights. I spent about 18 minutes waiting for traffic, which is not ideal (but at least it gives you some time to navigate). I brought some gels and a 0.75l water bottle, the public THF water fountains are usually running mid-May through late October. I didn't spot any other fountains right on the route, but there is also one close at Pettenkoferplatz by S Frankfurter Allee (though I didn't use it). I ran this on a Saturday around noontime and had no problems at Westhafen with access or security, though there are signs out. By FKT rules, given that this is a loop, you can start wherever you'd like. I would recommend starting heading into an area you don't know all that well, so that you can save familiar areas and your Kiez for the last 10–15km or so, so you won't have to spend mental energy navigating on the home stretch.
Thanks to A+A for helping me scout the route by bike a week earlier!