I’m 72 years old,160 lbs., and pretty good physical shape but only able to manage about 11-12 mph, working fairly hard, on a fairly flat paved bike way. It’s frustrating having so many riders easily passing and not being able to go a little faster. What should I expect speed wise under those conditions? I’m thinking about a road bike instead of this flat bar. I’m wondering if it’s me the old motor or the bike? Any thoughts on a different bike?