Stick with your current plan for Southern Cross then 2/18 take a week off training for recovery.
2/25 start the Masters 40+ Cross Country Base Training Plan. Replace some of the rides with runs and swims to train for your Xterra.
5/20 – recovery week off plan
5/27 start the 50 Mile Mountain Bike Race – Personal Record Plan . Add extra rest weeks to the plan to match your recovery speed. Follow plan week # 1, 2, 4 (week #4 is a rest week), 3, 5, 4, 12 (week #12 is a race week on 7/8/13 to rest and taper for Alabama Mountain Bike Series race), 5, 6, 7, 8, 9, 10, 11, 12 ending with a peak performance at Black Bear Rampage MTB endurance race on 9/8.
Lynda