Originally Posted by turtlendog
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Since you listed weight-loss as a specific goal, I'll HIGHLY recommend the road bike. Here are some reasons based on my personal experience.
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All of those things can be done on _any_ type of bicycle (including single speed cruisers!).
The bike does not care where you take it. I think you are trying to make a case for one type of riding versus another (road vs mountain).
A mountain bike workout can be as regulated and focused as a road bike workout and vice versa. I haven't actually bought a new mountain bike since 1994-- it now seems that you can't get a regular fork these days. I guess now the thing to get is a "hybrid" (my way of saying a 700c mountain bike with no suspension).
The thing about road bikes is that they are relatively expensive and demand a more aero posture. The original poster said he needed to loose weight. If it is a lot of weight, even a 45 degree angle could be hard to do.
Either way, have fun, pick something that fits you, and keep up the exercise.