AD, I would highly recommend going over to the CGOAB website, click on "journals" and then do a specific search in "locales" for Nepal so you can read some of the trip journals of people who have spent time biking in Nepal. This would be a great resource for you to get specifics and real world experience of folks travelling by bike, and knowing the country so well, you'll surely be very familiar with the areas discussed in the journals and would help you with getting ideas of a trip route.
Yes, I am familiar with this site-crazy guy on a bike.. I am also using his site to figure out what tools and spares I will take. and wether to take a tent or not. But other bike tourists I met last winter in Nepal did not take a tent. One Chinese bike tourist only had 10 kilos of gear! I dont think I will try to do that. I need a little more stuff. Also, I am quite big and so I can not buy clothes along the way--I have to bring everything with me. It is all second hand, like my ebay tools, and so if I need to I just give it away. I do that all the time. As I say in another post, I am using this first trip to familiarize myself with bike touring and if I like it I will know more next winter and plan a longer journey.