I am a new rider with only 50 miles on my new RadRover 5 here in Southeast Alaska. I seem to be having difficulty finding the best gear and or pedal assist for some very hilly packed gravel trails. Is there a "rule of thumb" for shifting up or down as well as the pedal assist. I am 80 years old and this part of riding off of the main roads is giving me a bit of a problem. Any advice would be greatly appreciated. Thank you for your consideration and help.