Originally Posted by
Rolla
While it's not the "same," it's still good. A rule of thumb is that if you plan to ride X miles in one day, you would be well served by regularly riding that far in a week.
I first heard this on BF several years ago, and have repeated it a few times myself. My typical ride is 15-20 miles, but I rarely miss a day and consistently ride more than 100 miles in a week. I decided I wanted to ride a century, so tried it and had no trouble doing 100 miles. (I've done it twice.) If you're consistently riding 85+ miles a week, you should be able to cover that in a day.