So now that we’ve got the introduction out of the way and hopefully you feel a bit better about how your skills, or lack thereof, are perceived, we can get into the nitty gritty. I’ll nail it down to three steps that’ll get you comfortably on the trail and into a new hobby.
Step 1: Find a bike. I’ve been asked by everyone from former motocross racers to women and men just looking at another way of getting into shape, “What bike should I get?”
My response has been the same since the first time the question was posed: Start on Craigslist and look for something that you can't buy at Walmart, Target, Dick's, or other big box stores. Those bikes are trash and you will just be miserable on your ride instead of enjoying it. Trust me, a good bike makes all the difference. Mass Market items aren’t intended for specialized use. You wouldn’t wear a Walmart brand shoe to run the New York Marathon, would you? You wouldn’t expect a mass produced Silverado Z71 to make it through the Baja 1000 just because it’s the “offroad package”. However, you can explore Baja in a Ford Raptor and you can run a local marathon in a good pair of running shoes. Approach a mountain bike the same way.
Start your search by looking for brands like Trek, Specialized, or a Giant. They make bikes that start new around $500 (all the way up to $10,000 plus) and can be easily found used on Craiglist. Just try to pay attention to the size of the frame, start here. If you want a new bike, go talk to the folks at your local bike shop. They will be absolutely stoked to help you out in every single way imaginable, then invite you to the trails, and then probably hand you a beer afterwards.
I started on an old, ragged out Giant that I picked up for $75 and it served me really well. It was equipped with the old school v-brakes (the rubber pads that rub against the rim, just like any Huffy you've ever ridden) and a pogo-stick for a fork. I can't even guess how old it was but the drivetrain was usable and the bike got me on the trails. I rode the wheels off of it then gave it to a buddy who joined me on occasional rides.
My next bike was a $200 Jamis that I also got off of Craigslist. It was also a hardtail but had an entry level Rockshox fork and hydraulic disc brakes with a pretty decent geometry. This type of bike is what I would highly suggest you look for. That bike is what took the idea of mountain biking from a spark to a full on flame for me. Man, I loved that bike... and I hope that whoever stole it out of my truck bed loves it just as much.
By the way, don’t get hung up on terms you’ll see a lot like ‘geometry’ and ‘components’. If you buy a respected brand bike, a modern geometry and respectable components will come standard.
Also, terms for bike categories are sometimes specific to brand but the type of bikes are universal. Here’s a quick and dirty buyer’s guide for the uninitiated:
Downhill: You do not need this.
All-Mountain/Enduro: More suspension than you need if you’re just testing the waters, can be very expensive.
XC/Trail: Start here. Whether hardtail or full suspension, you will be just fine with the amount of travel you get with these bikes.
You may never graduate to a full suspension, carbon framed, tubeless tired, dropper post equipped, all-mountain bike. But you might. The point is, start with a bike that will allow to test the waters but not something that will turn you off from the sport.
There’s tons of information out there from people that actually know about these things, aimed at people that know way more than I do about these things. You can reference articles like this from Singletracks.com or this from Evo.com to get a more specific guide.
Now, go get geared up.