hi robb!
i have some information about the spiti valley, but from 1997. you can find them
here .
at that time we had to obtain a permit in kaza, which was no problem at all. we never have had any hassles with the police. i also heard nothing about problems travelling in that area, except some severe landslides in the previous years (we also had to take a boat in 1997, as a huge landslide destroyed the road and a village in lahaul valley)
the landscape is fantastic, very dry (like ladakh and western tibet), so it is really a good idea to take this route!
i know one lady, annemarie, who had been cycling there quite recently in 2005. she is still on tour, you can contact her.
her site:
bikeworldtour.com the relevant diary (german only):
diary himachal pradesh i hope this helps you a bit.
do not hesitate to ask further questions...
cheers, lg uli