To put it simply, the 29" wheels are more stable. They are perfect for high speeds, give you a nice, smooth ride, and perform well on rocky terrain. They also provide you with more grip due to the larger contact surface, making it easier to pedal uphill. The 27.5" wheels on the other hand offer maximum manoeuvrability. Bikers who want a more playful and agile ride, and prefer smaller wheels, will love the 27.5". Mix is therefore the best of both worlds. The smaller rear wheel offers increased agility and manoeuvrability whereas the larger front wheel performs very well on rocky terrain on a downhill.