"You may not overtake right before or on a level crossing However, two-wheeled vehicles (aka: bicyckle) without a sidecar may be overtaken."

Driver license handbook

When there is wide roads and the visibility is clear: Allowed to pass, (Beter to pass a dangerous rail track with good visibility faster then behind a cyclist)
When its a narrow road and visibility is poor : Not allowed to pass (Due safety and other rules that might prevent you from passing, such as single lanes crossing)