Hi Nigel,
A couple of sources which might be useful -- I don't know if you have checked either of these:
1) I just did a "Delhi-Rajasthan" search on crazyguyonabike.com, and generated 179 references. Here's the link:
https://www.crazyguyonabike.com/search/?query=Delhi-Rajasthan&main_type=all You might try posting a request for advice on crazyguy, in the "Forums" or "Resources" section.
2) In 2005, my daughter and I spent a month in the Mumbai-Rajasthan area (travelling by train) and we found the Lonely Planet Guide to India to be an excellent resource for planning routes and accommodation. (Even in paperback it's a bit of a brick at nearly 1100 pages!) But, its information on cycling resources & contacts is limited. Lonely Planet does have its own forum, "Thorn Tree", and you might find some assistance there.
Good luck in any case, and take care on the roads, especially in the cities.