Most mountain bikes today are offered in one of two wheel sizes: 27.5˝ (also know as 650b) or 29˝ (called 29ers), with traditional 26˝ wheels reserved for dirt jump, freeride and kids’ bikes. These widely used measurements refer to the wheel’s diameter, and are typically paired with a tyre width in inches when written out, (i.e. 29 x 2.0, 27.5 x 2.4, 29 x 2.8). Here at Trek, we’ve been studying wheel size for nearly two decades alongside mountain bike legend Gary Fisher, and our breadth of experience has provided unique insights about the riding characteristics and best applications for each mountain bike wheel size. This guide provides a general introduction to the ride feel and characteristics of each wheel size that we offer to help you find the MTB that best fits the way you ride.