i think you should just ride your bike and not really worry about "training" with intervals and threshold power, etc. that century is probably going to take the better part of 7 hours, correct? i'd do 5+ hrs. on saturday, then 3+ hrs. on sunday, take m and fri off completely and do 1.5 to 2.0 hrs./day on tu/wed/thurs. that'll give you on the order of 12 to 14 hrs/week, with 2 recovery days, which i would think result in having the physical tools in place to complete your ride.