As per your interest we can plan a half day trip. Like we can plan a ride to Kathmandu Durbar Square with Mt. Bike. We can continue to Swayambhunath Stupa and come back. These both sites are World Heritage sites. We can park our mt. bike and visit the sites. As the route to Kathmandu Durbar square is narrow and small, we need to ride slowly. Or we have the option of pushing the bike. We are in the oldest market of the city when we ride to Kathmandu Durbar Square. And move toward the end of Swayambhunath stupa. It is quite hard as we need to ascend to the hill where Swayambhu is located. Here we will be able to see the Kathmandu valley on clear weather day.
Other option of half day tour is as follows:
Riding to Patan Durbar Square can be a half day tour. It is also a world heritage site that is under world heritage site. Likewise we can go to White Gompa and come back. Or we can go to any spot you would like to visit. So, there are many options for a half day tour. We will see your interest and plan accordingly.
