Separate your head from the gunk in your helmet. Honestly how often do you clean the liner in your helmet? Not often enough or never. Think of your helmet like your boots or athletic shoes, your sweat stays in your helmet and collects dirt, oils, and more all leading to bacteria build up. If you use a helmet daily or regularly buy a bundle pack of 3 or 6. That way you can always have a fresh clean skullcap to use, just like your socks.
If you are looking for a fantastic skullcap for any and all styles of helmets, the SCHAMPA's Traditional Stretch SkullCap is one of the best you can buy it is proven itself for nearly 20 years. Made with SCHAMPA's Stretch Fabric, the SCHAMPA Traditional Stretch SkullCap is a one size fits all piece of headwear great that is great for all seasons.