Kris Stallenberg 90-min Z3/4 (Sweet Spot) Pushing #10 This workout, 'Jagged Edge', trains your ability to handle changes in intensity within a sustained effort. Each 10-minute block includes a 2-minute surge to the top of the sweet spot zone, simulating micro-accelerations on a climb or in a breakaway. This builds a robust and versatile engine for real-world riding conditions. bike