I love this thread — thanks all for the insights. Great combination of airport and running knowledge. I have a FRA layover on two non-Schengen flights (US to FRA, FRA to BEG) from 15:00 to 22:00, with access to Sen lounges. To sanity check/confirm here, is this a reasonable plan:
1. Change into running clothes before landing, clear customs, leave carry-on at left luggage counter by T1 baggage claim. Bring cell phone + passport + physical credit card (just in case) on run.
2. Run to Frankfurt city, with a route similar to Wayan's Strava route from 2017 upthread
3. Have an early dinner in Frankfurt
4. Take SBahn back to FRA, pick up left luggage, go through customs, shower at Sen lounge, board flight

Three questions:
1. Any places you'd recommend for an early-ish dinner where I wouldn't feel too bad wearing running clothes (man, wearing tights + long-sleeve shirt, will bring a running jacket to look slightly less sweaty), ideally close enough to an Sbahn station that goes direct to FRA?
2. Given the 15:00 to 22:00 window here, would you aim to be back at FRA by [19:00, 19:30?] to allow time for customs and shower?
3. If I wanted to make the run a bit longer (thinking 90 min total), can I just keep running along the Main river for another ~15 min east of Wayan's end point?