Why biking in Bhutan?
One may also ask why not to bike in Bhutan?
If you do not like to cycle up and down mountains day after day or cycle uphill for stretches of 20 to 80 km: go to the Netherlands or Bangladesh.
If you like good roads to cycle on: Bhutan is a bad choice.
If you can't fix your bike if it breaks down: try India or a place with plenty of bike repair shops. However, don't expect the Indian bike fixer to know much about ultramodern featherlight superexpensive executive bikes, nor to have the appropriate spares or tools. But you may be amazed about the variety of problems that can be fixed simply with a hammer.
If you like to bike short distances only: Bhutan may not be your best choice, unless you prefer to bike around towns, or jump in a following vehicle when you get tired of it.
What is left as good reasons to bike in Bhutan? Plenty:
Bhutan has immense areas of undisturbed nature and even cycling along its "highways" one sees a lot of it.
The views are often stunning, but you are advised to stop before you look.
The climate in large parts of the country is quite pleasant for cycling, especially in spring and fall.
None of the main roads are very steep. The average percentage seems to be around 7%, which is what overloaded Tata trucks can manage.
Even on the highways there is little traffic, especially east of Wangdi.