I am a roadie who is looking for a frame on which I can ride both trails and road.. where I live in Nor cal there are some great trail rides split up by miles of roads. I would call it medium technical mtn biking stuff with roots and steep sections and rocks split up by 20 and 30 miles of road. I am looking for a bike that I could ride easily on the road and could take the pounding of the trails. I am considering the rivendell rambouillet or perhaps a straight cross frame. ANY GUIDANCE is appreciated... also any thoughts on tire selection for this kind of use... note.. there is some kinda steep downhill on dirt. THANKS!