ratebeer

It depends on your training prior to the race. There is no one-size-fits-all here.

You want to be rested and stronger prior to a major race. If you've been chronically over-training you will need more rest than you would otherwise. If you tend to push until your legs hurt a lot and for sustained periods of time, then you'll need more rest than if you focused on cardiovascular training or less taxing muscular training.

Some people try to gorge on improvements/training. Others take small nibbles. I'm a big proponent of the small nibble school. In which case, tapering simply means one or two days rest the week before the event and more cardiovascaular workouts (Tabata intervals) in place of a couple longer, faster rides. There's no need to rest more than you need.

With that type of endurance ride, you're probably doing at least 4 hour training sessions.
You probably shouldn't put in any of these after one week prior to your event, as fast rides at this duration could hurt for several days.