The challenge I found to riding long distances was learning when to eat.
Riding 20 miles is pretty easy, but any more than that and you need to be ready to eat along the way. Cycling requires somewhere between 600-1200 calories per hour, and I don’t have the ability to store more than about 90 minutes for a ride. Thus my long rides require that I train myself to digest and pedal at the same time.
It makes for some fun challenges. I’ll be testing different foods, but in the past I’ve used bagels, tortillas, and French toast. All are entirely carbohydrates and usable quickly as fuel. At least for me.
Your mileage may vary.