I've been riding (as an "adult cyclist") for about 20 years now, ever since my neighbors loaned me a hybrid and turned me on to the local bike paths, in say March of 1992. Since then I've mountain biked all over the USA, raced pretty avidly for a few years and still get out occasionally, and have done a lot of recreational road cycling. Here is a little info about the bikes I have, where I ride locally, and some of the places I've gone to mountain bike.
(things are still under construction, but we're getting there...)
I currently have
six five bicycles:
Giant Iguana: The Iguana was my first bike; right now it's set up as a commuter vehicle in case I, uh, ever feel like commuting... I did actually use it for commuting occasionally, when I lived in Easton, but now I mostly just use it to get around town.
Cannondale Super-V: The Super-V Active was the replacement for my original Super V 1000 (bought in January 1995, stolen & replaced in May 1995, and broken in the summer of 1998). This was a "restoration project" for years, then I finshed it and gave the bike to my friend Deb for her birthday.
Cannondale R800: My road bike, originally marketed (back in 1997) as a "fast recreational bicycle."
Turner O2: This is my main ride, and the best (and most expensive) I've ever owned. Good Lord is this thing fun... (The picture for this one is slightly dated, since I cracked the seat tube (Kingdom Trails, June 2011) and replaced the frame with the same model and year, but a clear paint job.)
Surly 1X1: A fully-rigid singlespeed. Very minimalist, very retro though I did go a bit overboard on the components.
Specialized Hardrock 29er: My newest steed and my entry into the 29" world, I actually won this bike in a raffle at Lake Nockamixon State Park's MTB Trails Grand Opening. (Photo coming soon.)
There are a number of good mountain biking rides in/near the Lehigh Valley, here are a few:
The Delaware and Lehigh Towpaths: Straight, smooth, flat and scenic. For what it's worth, the Lehigh towpath is the more primitive of the two -- this is my main "fitness and fresh air" ride after work.
Jacobsburg: About fifteen miles of moderately easy trails, mostly singletrack.
Round Valley: About twelve miles of hilly, technical trail around a New Jersey reservoir, this was my "training course" for many years.
South Mountain Park: Very technical riding in Bethlehem, maybe ten miles maximum but they're quality miles.
Walking Purchase Park:This is a new park, where local cyclists were given permission to build a trail system. There's maybe ten miles of singletrack, with probably the potential for another ten. More can be found at the Valley Mountain Bikers website, but here's a map:
View Sals in a larger map
South Mountain (Emmaus): Also very good technical singletrack, lots of fun.
Jim Thorpe Area: Probably over 100 miles of trails of all kinds, though many are now "off limits" because of new PA Game Commission rules. This is, or was, a popular mountain biking destination.
Allamuchy Area: A group of parks near Hackettstown New Jersey (Allamuchy & Stevens SP, Deer Park, and Kittatinny SP), maybe 100 miles or so of mixed single- and doubletrack. A tough place, and some serious back-country for New Jersey.
Update: Here is the link to my new local biking page, with trail info. That page (and sub-pages, part of a class project for an online course I took, which I intend to extend and complete) will eventually supersede the trail info here.
Every one of these comes with my recommendation:
Slatyfork, WV: this includes Snowshoe Ski Area and the Elk River Touring Center. Snowshoe has the better trails but Elk River is where to stay -- and the trails there are more scenic. Not many vistas, but a lot of greenery.
Northeast Kingdom, VT: