Simon Cowell has not let a brutal injury stop him from hitting the road again. RadarOnline.com has learned the legendary TV judge was seen riding an e-bike just four years after he broke his back and underwent surgery following a fall from one. The 65-year-old appeared confident during a ride on his e-bike, estimated to be worth more than $6,500, on the grounds of his mansion. The former American Idol judge was on the same grounds when he took a terrifying spill off his e-bike, a fall that led to severe injuries including a broken arm and three vertebrae. The accident led to a six-hour surgery…