Each year in Frankfurt, one of the three races of the German Tour takes place.
The race is lined with thousands of visitors who gather along the promenande next to the river.
At first, the athletes have to swim 3.8km in the quiet water of the Langener Waldsee.
After that, they have to cycle 180.2km. At the end they have to run 42.195km. The spectators who cheer for the athletes are very important.