If you妾檈 not quite ready to upgrade to the newest KICKR, Wahoo offers the KICKR AXIS Upgrade Kit so you can enhance the riding characteristics of your older KICKR. The AXIS feet replace the existing feet on your KICKR to support three different stiffness levels with the ultimate intention of adding more realistic riding sensations while you妾檈 hammering indoors. With the feet, the trainer moves side to side while you pedal instead of remaining fixed in place. At the 娓哸sy-actionlevel, you妾抣 have five-degrees of side to side movement for the most real-world riding experience. However, Wahoo makes it easy to swap out to stiff and medium levels depending on your specific ride goals. The purpose is to reduce fatigue on the cycling muscles that may get overworked when locked into a fixed trainer position and to recruit more stability muscles that require training to translate to outdoor-riding preparedness. The AXIS feet themselves are easy to install and swap out if you want to modify your ride from general training to sprint or race drills. And the feet are compatible with all versions of Wahoo KICKR, but not KICKR CORE or KICKR SNAP.