If you are riding more and harder than usual, rest days are important. Staying completely off the bike for days on end, is not. An hour of active recovery, spinning around, very low power, will do wonders. As was also mentioned, your legs will feel like crap as you get back on, but some of my most surprising workouts have been when the first ten minutes, I questioned whether I could even complete an interval, much less nail it. Just because you're on the bike, doesn't mean you have to try for the hour record.