Howdy forum

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I have spent some time lurking here and must say I am impressed with some of the level headed advice given by members. I fully expected to see ppl recommending 2 ... 3 ... 4 thousand dollar bikes to n00bs and that sort of thing. I am hoping to participate here and become a frequent visitor.
I have read quite a bit and peeped the thread about how the site was founded. Looks like a good place for me

. Not new to forums so I appreciate anybody who can help me with my n00bie questions. I realize answering the same things over and over can be monotonous.
As you may have guessed from my sign on, I am a chubby fella ... looking to lose some weight. I need something really low impact as I have had some issues with my lower back including a 4 month bout with sciattica in early 2009. I am 44 years old. I have not been able to exercise for a while but am well now. I am new to cycling and have not ridden in years. I have looked into other equipment and types of exercize, but have really been inspired to take up cycling.
In my first post here, I would like to have a big helping of some of that sage advice I have seen offered to others re: the quintisential n00b question,
please help me choose a bike.
I know you all need some input, so here is what I can share with you. I am in the hybrid section because I live very close to our community trail network that is made up of hardpacked dirt and pea gravel. There are also extensive sidewalks that are paved. I need a bike that will be versatile enough to give a moderate work out on both surfaces and probably some gravel road shoulders as well.
My budget is around 500 USD.
I have visited a few LBS and discovered that I *think* I want a riding position that is somewhat leaned forward. I do not want to sit straight up and get all the road shocks from the rear tire up my back, nor do I want to be leaned way forward a-la Lance Armstrong

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I *think* I want sprung front forks but most of the ones with lock out are out of my price range.
I really want a bike that is from an American company, and yes, I realize that even at that a lot of parts and assembly are done overseas. Just trying to be as patriotic as I can with such a large purchase in hopes thqat at least a portion of it can keep someone working here in the US. So ... in my reserach I have narrowed it down to 2 companies ... Specialized and Trek.
So far I have seen and tried the
Specialized Sirrus and Sirrus Sport, and the Crosstrail. I have also looked at the
Trek FX 7.1, Hybrid 7000, and 7100 ... the Navigator 2.0 which seems to be the bridesmaid, and finally the Gary Fisher Bodega which I am leaning towards.
I like the seating position of the Bodega, but am really struggling to find any reviews. I am hoping that the more forward lean that it has over the Navigator will not become tiresome or stressful over a longer ride.
So ... that is where I am at. I am absolutely certain I have overlooked brands, models, and criteria. I am trying to make a sound choice on a first bike and the amount of info is sometimes overwhelming. I would appreciate any guidance anyone can offer.
BTW, my name isn't really Clyde

. Sorry about the wall of text.