[Gocamino] Camino by bike?

[Joyce Cheney]

Having walked the Camino for the first time this Spring (Pamplona to
Santiago), I've been sharing pictures and stories non-stop since then. My
sister would like to make the pilgrimage with me next spring -- by bike.
I'm concerned that bikers have two choices, either of which seem to have
serious drawbacks when compared to walking:
1)take a road bike and end up missing little towns and spending lots of time
dodging traffic, 
2) or take a mountain bike on the walking path. During my walk this year, I
saw only two people doing that -- that option doesn't seem to be real
popular -- and those two were having a hard time.  Yet I just read a website
by a Camino Pilgrim-by-bike who recommends following the walking path on
mountain bikes.  

Is there someone who has ridden the roads/path who can share experiences of
those two options - how they compare to each other and how they compare to
walking?

Thank you
Joyce