Cycle route, Chiang Rai to Laos taking in Isaan & Nan

Hi, i am planning a cycle route from Chiang Rai through Laos to Vietnam but want to ask here about possible cycle routes from Chiang Rai towards Laos. I can cross any border point in to Laos but want to be heading down to mid Laos to cross to Vietnam. I will be travelling by touring bike and camping or staying at guesthouses on route. I've been around Chiang Mai and Chiang Rai but never between Chiang Rai and Laos and would like to find a route taking in the beauty of the Isaan territory and Nan too as i hear this area is also very beautiful.

Any advice on this route or such a touring trip would be appreciated...