The area is quite flat, so the cycling isn't very strenuous.
Angkor Wat Temple is an amazingly inspirational place to explore. The complex is also very big. A carbon-free, adventurous way of exploring the area is by bike! Bike hire is available in Siem Reap without pre-booking and often doesn't cost more than $5 per day. From the city it's a short 4.5 miles drive to the complex. There is a bike lane running 14 miles around Angkor Archaeological Park which is an easy way to explore the area. The area is quite flat, so the cycling isn't very strenuous. At the same time you'll need to keep your wits about you. Perfect for a novice adventure traveler!