Take a rest day 2 days before, not the day before.
If you're training hard to get ready for a race, century, day-long tour or other important event, you want your legs to feel fresh on the big day.
Logic may say to rest the day before, but we'll bet you'll feel livelier if you ride instead -- as long as you ride right.
Let's say the event is on Saturday. Reduce your training time during the week to begin saving energy. But continue pushing some hills and doing some sprints or short time trials. This intensity will keep you sharp as your mileage decreases. Just don't overdo the hard stuff.
Then use Thursday for your rest day. Don't ride more than for a short errand.
On Friday, spin for 60-75 minutes. Once you're warmed up, throw in 3 or 4 short, fast efforts. Don't go all out, just wind it up for 20-25 seconds and then spin easily before the next one. Finish in time for a 15-minute cool down.
These accelerations "wake up" your legs. There's less risk of them feeling groggy at the event, as they might if they're basically asleep for the previous 36 hours.