Which Mountain Bike should I buy?
Mountain bikes come in a wide range of types, with each type having its specific use and terrain you will be riding in. Mountain Bikes include sports like Cross Country (XC), Trail, Enduro, Freeride, Dirt Jump, Slopestyle, BMX and Downhill mountain bikes. Of all bikes sold in the US, Mountain Bikes are by far the most popular model of bicycle mainly because even though designed for off-road riding, these are also versatile enough to be used on the road. They are designed with durability in mind, as they have to withstand much greater wear and tear whilst off road.
The most common are Hardtail Mountain Bikes, with a lower price point, these bikes feature a suspension at the front while the rear is a solid part of the frame. These bikes are often more affordable and lighter than dual suspension mountain bikes. However, as the trail gets rockier, you will find yourself looking at a Dual Suspension Mountain Bike, which features a suspension at the front and the rear. These dual sprung bikes absorb bumps a lot better and are quicker to find traction in challenging trails. Difficult trails will demand more suspension travel as you descend to be able to cope with the increasing speed and obstacles you encounter. More travel does mean that your bike will be suited for a wider variety of trails and bigger jumps.
However, more suspension travel is not always better. In your next bike, you want to make sure you get as little travel as possible for the trails you're riding in. Although counter-intuitive, this ensures your new bike is not overkill for the trails you ride, it keeps being weight low and might even save you a few dollars down the road. XC bikes feature 100mm to 120mm of travel, Trail and Enduro bikes run 140mm to 160mm of travel and Downhill bikes come with 180mm to 200mm of travel. Remember this, the more travel you have available, the harder it is to pedal the bike uphill.
With all these mountain bike types, there are also different wheel sizes, 27.5 inch (650b), 27.5 Plus and 29 inch (29er). The larger diameter wheels are easier to roll over obstacles, but the bike becomes less agile, slower to accelerate and a tad heavier. You should pick your wheel size based on your height, riding style, and cost.
Dirt Jump, Slopestyle and BMX bikes are specifically designed for big jumps & tricks on skate parks and dirt jumps. These bikes aren't designed to be pedaled due to the saddle position and general bike geometry, which places all components as close to the ground as possible to allow more room for aerial maneuvers.
Frame sizes are measured in inches, or sizes such as Small, Medium, Large and Extra Large. You often have fewer size options when compared to road bikes, mainly because you move your body weight forward and backward as you negotiate obstacles, climbs, descents, and jumps. With that in mind, bike designers create frames that offer a lot more adjustability within size options.