Originally Posted by JimStl
Sounds like the arrow dynamics of the windscreen creates a pretty hard low pressure zone on the underside of the window and the area above the tank to below the shoulders. Guys are reporting some pretty strong buffeting.
I run a decent sized tank bag pretty much all the time, and I've never experienced that problem. As with most things, it will really depend on the rider's size, the way they choose to sit on the bike, and what else they change (like a tank bag, or not) that will change the airflow.