When I started biking seriously in Jr. High, ten-speeds were all the rage. My first real bike was a Raleigh Reliant of ’82 or ’83 vintage. I proceeded to ride a two day MS 150 from the Twin Cities to Duluth, but mainly just rode around the area I lived (suburban St. Paul, MN). I brought the bike with me when I moved to Washington state in ’91, and did some bike commuting.
On a summer trip to Whistler, I got my first taste of Mountain Biking. A friend had just bought a Diamondback, and suggested i take it up the jeep road for a spin. After struggling up the rocky road, all the while marveling that I could even stay upright, I found a smooth dirt path that was fairly level. This led to a steep ravine down ‘n up that was covered in 2-3’ chipped stones. My tires barely touched the ground as I sailed down it the first time, and I nearly came off the bike. I was laughing so hard at my near death experience, I had to repeat it a few more times before returning to camp. I felt something that I had forgotten about. I felt like the kid I had been in the seventies riding my bike everywhere – dirt, field, or road. Soon after getting home, I bought my first mountain bike.

Revived "first mtb"
Looking back, what I discovered wasn’t so much a different class of bicycle, but just the joy of riding a bike on rough dirt/rock trails. Big tires made it easier, but it could have been any bike in that setting, and others like Grant Peterson of Rivendell, or Chris Kostman of Adventure Corps who needs a MTB? maintain that there are many ways to ride off-road.
I renewed this love again this summer at nearly the same place it started for me with a short ride in the hills surrounding Whistler Village. I went for a ride with a friend and encountered some great singletrack. I had the same feeling of being a big kid in the dirt even though i was riding an old bike with drop bars and smooth (albeit fat) tires.

Drop Balloon Bike in the Woods
My daughter and I recently went to a more local venue near Seattle called Duthie Hill. We had an incredibly fun time doing the beginner loop and really enjoyed the smooth, flowing sections. It feels a bit like skiing at times. Just one continuous smooth flowing ride down a hill through the trees. We saw a lot of guys with modern kit like full face helmets and pads riding monster travel full suspension bikes. Great stuff for the more technical trails, but not necessary for our fun ride.

"New" MTB
I will always love riding the dirt, and some of the best is here in the NW!
Nothing like it!