1. Just because you haven't seen them "addressing" crime doesn't mean they haven't been. (Personally, I have seen bike cops collar at least one suspect.) And mere police presence can deter criminal acts.
2. As the headline and article point out, their patrols are not limited to trails.
3. As the article also points out, police interaction with community members is important. Much easier to talk with a bike cop than a cop in a patrol car.