The area around Srimangal is one of the best in Bangladesh for cycling. Despite the rolling terrain, the roads are reasonably level;
if overly encumbeared rickshaw-wallahs can do it, then so can you, even on the ubiquitous one-speed chinese bike.
There's an intricate network of roads connecting all the tea estate to the main highways. Only the major routes are tarred or bricked, but the dirt roads are in good condition.
Even if you just head east out of town on Kamalganj Rd and stay on the main roads, you will find yourself weaving in and out of heaven in no time.
It can be difficult to determine where one estate stops and another starts. Bear in mind that you might inadvertently pedal into private property.
Though you will find that most people are more likely to treat you like a guest than a trespasser, it is appropriate to seek management's permission to be there. You can try your luck in asking for accommodation at the tea estate, but don't assume you'll be successful - allow enough daylight hours to get back to town.