What vehicles may enter a zone with this sign?

This sign marks a bicycle zone where only bicycles and certain small electric vehicles (like e-scooters) are allowed. The additional sign "Anlieger frei" means residents or people with a direct reason to access the area (such as residents or deliveries) may also drive in. So, in this case, bicycles, small electric vehicles, and vehicles of residents or people with legitimate access are all permitted. You chose correctly and understood that all three groups listed are allowed to enter this zone. For similar signs, always check for additional signs like "Anlieger frei," as they specify further allowances beyond the main sign.