Each season when I start out I begin with 2 - 11 mile rides. Then 1 day off and then 2 - 18 miles rides and then a day off. I usually just keep increasing like that until I get up to about 50 miles. I usually hit a plateau around 30 - 35 miles, spend about 2 weeks doing that mileage and then start bumping it up again. 50 miles is my sweet spot for about 2 rides a week with maybe a 30 mile ride in between.