Rotor designed the BB30-BB24 Converter Mountain Bike Bottom Bracket to make changing components between frames a breeze. Now you're able to use the 24mm cranks of your choosing with that BB30 frame. Rotor created a smooth, aftermarket converter using its labyrinth seals. Labyrinth seals have a series of grooves, or teeth, where the male and female pieces slip together -- often perpendicular to the threads. These grooves create a maze that fluid would need to pass through in order to create a leak. Additionally, the labyrinth seals provide unparalleled protection from elements such as dust, water, and mud. Most importantly, though, this converter allows you to run a conventional BB24 crankset with a BB30 frame. And even better, at around 120 grams, it allows this without stacking up needless weight. The Rotor BB30-BB24 Converter Mountain Bike Bottom Bracket is compatible with conventional BB24 cranks from Rotor, Shimano, and Shimano-compatible brands. It features steel bearings, and it's available in the color Black.