I have a full Shimano Deore drive train that I would like to use for a cyclocross bike with a pair of Tiagra STIs. I am pretty sure that they are both 9 speed. Will there be any compatibility issues that I need to deal with. I seem to remember reading something on Sheldon Browns website about Shimano using different spacing (and thus different cable pull) for there mountain and road components.

I am still new to working on bikes so I don't know all of the ins and outs but hope to learn as I go. Also, is there one book that is worth investing in or is YouTube really the way to go?