The starting point is the Explorer Hotel Oberstdorf. From here, turn left towards Fischen. After a short while, you'll reach traffic lights; continue left, where you'll see the first signs for the Riedberg Pass. After passing Obermeiselstein, the gradient becomes steeper, and shortly afterward, you'll reach the steepest section at 16%. Don't worry, it's only a short section of about 600m. Your effort will be rewarded with the beautiful views all around you.
At the top of the pass, you'll also have a good view of the Riedberger Horn. It's well worth hiking up here, or, if the snow is good, ski touring or snowshoeing. You'll also find tour descriptions here ;)
Once you reach the top, your calves can rest for a while, because you still have a relatively long descent ahead of you. Continue on towards Hittisau to Krombach in Vorarlberg. From here, it's back to Germany. You head towards Oberstaufen, past the Alpsee, where you can take a well-deserved swim. Then you continue to Immenstadt. From here, it's not far! If you're on a gravel bike, you can follow the Illerradweg to the hotel. Otherwise, you can take a relaxed bike ride back to Oberstdorf via Burgberg on the country road.
Back at the hotel, you've earned a refreshment at the bar! Because you've successfully conquered THE pass in the Allgäu!
PS: Along the way, you'll pass numerous small cafés and beer gardens. Here you can refuel with a beautiful view!