Just started cycling again after a 30 year layoff. I'm currently riding a Motobecane Fantom 29er mostly on gravel/dirt trails along a canal. I've ridden about 100 miles a week over the past two weeks. My legs have been screaming at me for the past two days. Am I pushing too hard, too soon? Should I be doing less miles and building up for longer rides. I've been averaging about 12.2 mph per ride and doing about 27 miles a day in just over 2 hours.