29-inch wheels are a popular size for mountain bikes, offering a larger diameter compared to traditional 26-inch wheels. This size provides better rolling efficiency over obstacles like rocks and roots, making it easier to maintain speed on rough terrain. The increased circumference also enhances stability and traction, which can improve overall handling. These wheels are often paired with wider tires, allowing for better grip and comfort during rides. Many cyclists prefer 29-inch wheels for their ability to cover ground quickly and smoothly, making them a favored choice for both recreational and competitive riders in the mountain biking community.