A mullet setup pairs a 29-inch front wheel with a 27.5-inch rear wheel on the same bike. The idea is to give you the best of both worlds: the larger front wheel rolls over rocks and roots more easily and holds momentum on rough descents, while the smaller rear wheel makes the bike feel more playful and easier to maneuver in tight corners or off jumps.
This configuration has become especially popular in enduro racing and aggressive trail riding, where you want front-end stability at speed but still need quick, snappy handling when the trail gets technical. The smaller rear wheel also allows designers to use shorter chainstays, which makes the bike feel more responsive and easier to manual or whip.
One important catch: you can't just swap wheels on any bike. Mullet setups require a frame specifically designed for mixed wheel sizes, so if this appeals to you, look for a mullet-specific model from the start.