Spank Subrosa Lock-On Grips
Superhero grips from Spank will make your handlebars go really fast. And if your handlebars are secured to the bike via the stem, and you're sitting on the bike, that means you go really fast too. A tacky micro-diamond pattern will keep your hands calm, cool, and collected even when you're hanging on for dear life. These comes in a wide variety of colors so you can color match your ride.
Have ran these on a XC bike and a Dirt Jump bike. Diameter is fairly small and width is just enough for most adult hands. Excellent grip and feel when new but the pattern is fine and they wear quickly. With gloves they still grip OK when they are getting smooth from wear.