Right now, as a general plan I'm thinking to focus mainly on hard tail bikes, since those are the entry level and suitable for the majority of people. As the guide develops then it can be expanded with more information concerning the more advanced and expensive bikes. I think the important thing for the guide is for a reader to easily see what is the best bike, and what is the best value, but also have a ton of information backing up those claims if they want to dig further. Also the guide should be a general reference point when it comes to maintaining and upgrading the various components on the bike.
Sources of Information
Mountain Bike Review ForumConsumer SearchPeople
It would be good to get information from bike store owners and people that are very enthusiastic about the sport, but not necessarily in the online space. I plan on taking some visits to the local bike shop and see what kind of advice they'll provide.