Originally Posted by mouthfulloflake
the fan moving , while the bike is in motion, is still a detriment to the flow and cooling in my opinion
show me your temps and how the fan improves them and I will understand I guess.
Yeah, you are 100% correct. A fan with a cowling snuggled up to the downstream side of the rad has to reduce the airflow to some degree.
The question is how much airflow reduction can the system absorb without comprimising it? I think a hell of a lot. She'll still run half caked with mud ie. 50% blocked. BMW also installs the fan on the police models of the 1200 to cool the pig when there is no flow over the rad.
I think it's fair to say the system will handle the small airflow reduction that occurs while in motion quite easily. It's all about cooling the pig when there is no airflow.