I lived in the West End of Portland, Maine last summer, and am back again for the summer.
Last year I biked around the neighborhood frequently. It was a great way to get long stretches of space, with few cars or pedestrians in the way.
There are no hills for a real workout, nevertheless, it is marvelous for long expansive wide roads that connect easily.
Another wonderful place to bike if you are in this area is over the Casco Bay Bridge into South Portland, via State Street.
If you are new to living in the West End, or only visiting for a short time, you may enjoy renting a bike for the pleasant excursions.
Gorham Bike and Ski shop on Congress Street I suspect rents bicycles. If not they could easily tell you where to go.
Once you cross over the bridge you can make your way to Willard Beach--a wonderful local ocean spot with residential locals and a calm environment. Since parking is not always abundant in the summertime, biking is a great alternative.
There is also SMCC which houses a fabulous place to swim and hang out on the water with great views and more walking paths.
However, if you aren't interested in that long a bike ride, as I mentioned initially, the West End itself is smooth and fun to coast in a relaxed manner. Making your way to the Western Prom is also special, with an open but inviting woodsy feel.
Almost all roads will lead you there. And if you can't find it simply ask.
People in that neighborhood love sharing their promenade view with visitors.
As a daily walker, I am grateful to have quick access to the West End of Portland any time of day.