Cycling as an activity on Apple Watch

On the watch open up the workout app, scroll down till you see outdoor cycling or if indoors choose indoor cycling

They are already there.

1. Open the Watch app on your iPhone.
2. Tap the My Watch tab.
3. Tap Workout.
4. Tap Workout View.
5. Tap Multiple Metric (the default) or Single Metric. When you select multiple metrics, you can select up to five metrics for each type of workout.
6. Tap the workout type.
7. Tap Edit.
8. Tap the green add button to add a metric.