Simply put, it is like this: Stability through 29": 29" is optimal for high speed and smooth riding, providing better rollover behavior. At the same time, the larger contact area offers more grip. The bike is easier to pedal uphill. Maximum agility with 27.5": For all bikers who prefer a playful and nimble ride with smaller wheels, 27.5" is the right choice. The best of both worlds: The mix is more agile and maneuverable with the smaller rear wheel. With the large wheel in front, obstacles are easily overcome.