I ride by Riverdale a few times a week, I come into manhattan from scarsdale. bronx river road, up gun hill and down to broadway and take broadway into manhattan. You can do a 20 mile commute each way, three days a week easily...I've done it year round for almost 4 years, and I'm 50 years old. I will say if you try to up the days from 3 to 5, you'll start falling asleep during the day, but lunchtime naps are awesome !!!