This example uses FlexiCharts to compare average power and heart rate across cycling rides, separating workouts without GPS from those with power data and a specific heart-rate range. The code chains `.filter()` and `.line()` calls on ride aggregates, drawing purple and teal lines for power and heart rate, while `.on(-1)` places the heart-rate series on a secondary axis. A final `.group_by(week).aggregate(average).line()` renders weekly trends of power at a 150-watt threshold (pwc150). Data comes from cycling analytics ride summaries, rendered as lightweight SVG-like line charts.