I wear a Shoei RF1200 helmet and I made sure it fitted inside the frunk before I bought the bike. I got a bug up my butt lately and been looking at modular helmets. I stopped at Cycle Gear to check some out in person. I first looked at the Schuberth C3 Pro. It was a nice helmet but it felt tight around my jaw. They let me bring it out to my bike and test fit it inside the frunk. It fit without issue, it was actually smaller then my RF1200. The next one I tried on was the Shoei Neotec 2. It was a really nice fit just like my RF1200. I couldn’t close the frunk lid with the Neotec. It wouldn’t even fit in my Givi 37 liter pannier, what the hell? I guess I will wait until the Schuberth C5 hits the stores in the US and try it out.