Check out the difference in rear profile of the X-Fourteen on the left vs. the RF-1200 on the right. Notice the X-Fourteen has the extra body-work which extends rearward.
This overhead view shows you how much more body of the X-Fourteen helmet extends rearward along with a boat tail shape to reduce the size of the wake behind the helmet reducing drag. It’s like the boat tail extensions that are sometimes attached to the rear of semi-truck trailers to reduce their wake size.
The last bit of aerodynamic work is related to noise. The RF-1100 on the left has two sets of rear vents and it had a loud whistling noise when the front pair was open. So I never had them open which pretty much defeated their purpose. It’s a bit hard to see, but the rear most vents are open and the fronts closed. The RF-1200 on the right largely addressed the whistling noises from the helmet. Every once in a while, I’ll get a whistle noise from what seems like the edge of the visor when the visor is in the fully locked down position. There are no such noises from the X-Fourteen.
Another little trick for reducing drag is vortex generators on the trailing edge of the visor.
To get an idea of what the two helmets look like while in a semi-tucked riding position, I posted the camera up and got on the bike with both helmets. Using a little Photoshop magic, I was able to overlay the helmets so that you can see the differences in profile and how the X-Fourteen has the extended body work. And yes, I look goofy trying to do a tucked position while standing the bike vertical.
Overall, it’s a great helmet and one to seriously consider if you do track days and/or ride in hot weather. The airflow through the helmet is definitely a step above the RF series keeping you as cool as possible. The added stability means there’s one less distraction when you’re trying to focus on riding. The X-Fourteen is the top-of-the-line model from Shoei and maybe, just maybe, hell will have frozen over a couple years from now when I need a new helmet.