How to Choose Mountain Bikes

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two people riding mountain bikes on a trail

Trying to figure out which mountain bike is right for you? Here’s how to approach the question:

  • Bike style: Different riding styles require different bike styles, so your first consideration is where and how you plan to ride.
  • Key features: The biggies are suspension, wheel size, frame materials, gearing and brakes.
  • Fit: Last, but not least, be sure your bike fits you well. This is best done in person at a bike shop like REI.

Note: This article covers the basics of mountain bikes. (See below for a brief glossary of terms used in this article.) For a more detailed discussion, talk with the bike pros at your local REI store.

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Types of Mountain Bikes

Trail Bikes

Trail Mountain BikeThis is arguably the most common mountain biking style because the category isn’t grounded in any specific type of racing. If you’re interested in meeting up with friends at the local trailhead and riding a mixture of climbs and descents, then this is the style for you. Bikes in this category place equal emphasis on fun, efficiency and sensible overall weight.

Typical specs: 120–140mm of suspension travel; 67–69° head-tube angle

(Suspension travel is the amount of movement offered by the bike’s front and rear suspension. Head-tube angle is the angle that the head tube forms with the ground. A steeper head-tube angle generally indicates that a bike will turn faster and climb better. A slacker (lower) angle generally indicates that a bike will provide better stability at high speeds but won’t climb as well.)

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Cross-Country Bikes

Cross-country mountain bikeThis style of riding typically implies riding fast, with an emphasis on climbing prowess. Distances vary from just a few miles to 25-plus, and bikes tend to focus on efficiency and low weight. These bikes can be great if you’re considering getting competitive or would like a racier ride for your local trails.

Typical specs: 80–100mm of suspension travel; 70–71° head-tube angle

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Fat-Tire Bikes

Fat bikeOversize tires, from 3.7 in. to 5+ in. wide, give these bikes excellent traction, especially in sand or snow. Fat-tire bikes are great for beginners because the wide tires are reassuringly forgiving as a rider picks a line through rough terrain.

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All-Mountain Bikes

All-mountain mountain bikeThink of all-mountain riding as trail riding on steroids, with bigger leg-burning climbs, longer, scarier descents and more technical features—both man-made and natural. Bikes for all-mountain riding are designed to perform well on steep descents while also being light and nimble enough to pedal uphill.

Typical specs:140–170mm of suspension travel; 65–68° head-tube angle

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Downhill/Park Bikes

Mostly ridden at lift-serviced bike parks, these bikes aren’t sold by REI. Downhill bikes are big and tough, and riders wear full-face helmets and body armor as they encounter jumps, berms, rock gardens and wooden ladders.

Typical specs: 170–200+mm of suspension travel; 63–65° head-tube angle


Mountain Bike Features

Suspension type and wheel diameter are two key attributes that determine the type of terrain a bike is capable of handling. You’ll also want to consider things like frame material, number of gears and type of brakes as you narrow down your bike choice.


Mountain Bike Suspension Types

Rigid mountain bikeRigid: Not the most common type of mountain bike, “rigid” mountain bikes don’t feature any suspension. They are easy to maintain and usually less expensive, but most riders prefer bikes with suspension for greater comfort. Most fat-tire bikes are rigid because riders find that the wide tires and low tire pressure provide all the squish needed to absorb bumps on the trail.

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Hardtail Mountain Bike


Hardtail: These bikes have a suspension fork in the front to help absorb impact on the front wheel, but the rear of the bike has no suspension—ergo a hardtail. Hardtails are typically less expensive than full-suspension bikes and have fewer moving parts (which often translates into less maintenance). Most hardtails have the ability to lock out the front fork for times when a fully rigid bike is desired.

Cross-country riders typically gravitate toward hardtails as these bikes allow more direct transfer of power between the pedal stroke and the rear tire. Hardtails can also be at home on all-mountain trails, and the lower cost and easier maintenance make them a solid option for everything except serious lift-serviced downhill trails.

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Full suspension mountain bike


Full suspension: There are many variations of full-suspension bikes, but the general idea is for the front fork and rear shock to absorb the impacts of the trail. This drastically reduces the impact on the rider, increases traction, and makes for a more forgiving and enjoyable ride.

A full-suspension bike can soak up a lot of a trail bumps and chatter, but the bike can also “bob” a bit and you lose some of the energy transfer when climbing uphill. As a result, most full-suspension rigs have the ability to lock-out the rear suspension to offer better power transfer and more efficient climbing.

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Mountain Bike Wheel Size

Mountain bike wheel size26 in.: In the not too-distant past, all adult mountain bikes were equipped with 26 in. wheels. It still is an available wheel size, but now when you walk into a bike shop and inquire about mountain bikes, you are likely to be asked, “26 in., 27.5 in. or 29 in.?”

27.5 in. (650b): Offering a middle ground between standard 26 in. wheels and 29ers, these bikes apply a “best of both worlds” solution, more easily rolling over terrain than the 26s, but more maneuverable than 29ers. 27.5 in. wheels can be found on both full-suspension and hardtail rigs.

29ers: These bikes feature 29 in. wheels that are a little slower to accelerate, but once you start moving you can conquer considerably more terrain far easier than on a bike with 26 in. wheels. They are more efficient for longer rides as they keep their momentum up and they have a higher “attack angle,” meaning the wheel rolls over trail obstacles easier. These bikes have become extremely popular for the cross-country crowd. 29ers can be found in rigid, hardtail and full-suspension rigs.

For help choosing between 27.5 in. and 29 in. wheels, see 27.5” vs. 29er: Which Mountain Bike is Right for Me?

27.5+ in.: The plus symbol simply indicates extra-wide wheels and tires, typically 2.8 in. or more in width. Wider tires offer a more comfortable and more forgiving ride. They also encounter less rolling resistance, so the trend is for bikes to have wider wheels and tires these days.

24 in.: Kids’ mountain bikes typically have 24 in. wheels to accommodate the shorter legs of children. Most are less-expensive versions of adult bikes with simpler components. Generally speaking, these suit kids ages 10 to 13, but this depends more on the size of the child than the age. Younger/smaller children can get started on mountain bikes with 20 in. wheels.


Mountain Bike Frame Materials

The frame influences a bike's weight, strength, longevity, ride quality and price.

Aluminum alloy is the most commonly used material for mountain bike frames. Some more-expensive models have lighter aluminum frames as a result of the manufacturer expending more dollars and effort in the selection of materials, tubing design and the manufacturing process.

Other frame materials include steel, titanium and carbon fiber. Steel is tough, inexpensive and offers a smooth ride, but is relatively heavy for a mountain bike. Titanium is light and strong but too expensive for all but high-end mountain bikes. Carbon fiber is fairly common on cross-country bikes, fat-tire bikes, and high-end trail and all-mountain bikes because of its strength and low weight, but it is relatively expensive because it requires labor-intensive manufacturing.

For more information, see the REI Expert Advice article, Understanding Bike Frame Materials.


Mountain Bike Gears

The number of gears a bike has is a result of the number of front chainrings multiplied by the number of sprockets on the cassette. Mountain bikes are available with everything from a single speed to 30 or more gears. When you factor in the many combinations of chainrings and cogs and the numbers of teeth on them, things can get complex.

To keep it simple, the most important things to consider are your fitness level and the terrain you'll be riding. If you'll be riding lots of steep hills and you find climbing challenging, then you'll want to opt for more gears. If you're a strong mountain biker or you only ride flat terrain, you won't need as many low gears to power up a hill so you can get away with fewer gears, which will also help keep your bike light.

Mountain bikes have traditionally come with two or three chainrings to provide a variety of easy gears for climbing. However, mountain bikes with single chainrings and a wide-range cassette with 9, 10 or 11 cogs are now very popular. Bikes with one chainring are lighter and simpler because you need only one shifter to move through the gears on the cassette, and they offer most of the gears you’ll need.

Keep in mind that bike gearing is fairly easy to modify after you buy a bike, so it doesn’t need to be your primary concern when choosing a bike.

Learn more about bike gears in our article, Bike Gears and Shifting Basics.


Mountain Bike Brakes

Disc brakes have replaced rim brakes on all but entry-level mountain bikes.

Disc BrakeDisc brakes: These feature brake pads that grip onto a brake rotor mounted to the wheel hub. Disc brakes come in two versions: Hydraulic disc brakes offer more progressive and stronger braking with less finger effort, and they self-adjust for brake pad wear. Cable-activated (mechanical) brakes need manual adjusting as the pads wear.

  • Advantages compared to rim brakes: More consistent braking in all conditions; much cheaper to replace a worn rotor than a whole wheel; superior performance in steep and wet terrains; less finger strain.
  • Disadvantages compared to rim brakes: More difficult to inspect pad wear and replace pads. Hydraulic brakes are more expensive to service.

Rim BrakeRim brakes: Some entry-level mountain bikes come with rim brakes. Rim brakes feature pads that grip onto the wheel rims.

  • Advantages compared to disc brakes: Economical; easy to observe brake pad wear and replace worn pads.
  • Disadvantages compared to disc brakes: Gradually wears out the wheel rim, requiring the wheel to be replaced; less stopping power; less effective in wet or muddy conditions; requires more finger effort on the levers to brake aggressively.


Mountain Bike Fit

Mountain bike fitA bike that fits well and is right for your height, flexibility and riding style is a bike you’ll love riding. A properly fitting bike can improve your handling and confidence on the trail to help you tackle more technical and challenging rides.

How mountain bikes are sized: Mountain bikes come in standard sizes (S, M, L) and are generally similar across brands. Sizes generally correspond to your height. Many bike manufacturers include size charts that list a height range for each bike size. If you’re in-between sizes, it’s best to err on the smaller side as more sizing accommodations can be made with a smaller frame than with one that’s too large. To learn more about fitting a mountain bike, see our Mountain Bike Fitting Basics article.

Get the best fit by going to a bike store: Armed with a general sense for what kind of bike you’re looking for, now is a good time to head to REI or another specialty bike retailer to identify some suitable models and try out a few bikes. That’s the best way to get the best fit.

Go for a test ride. Ask to ride several bikes. With the help of a sales specialist, you should be able to narrow down your selection to two or three bikes. Though they may have similar prices and components, each will feel different to ride. Take each on a five- to 10-minute ride over some varied surfaces, including up a short hill. In most cases, one bike is just going to feel better for you than the others. You want a bike to feel like a natural extension of your body.


Mountain Bike Maintenance

Any REI bike shop will give your bike a final mechanical safety inspection before you wheel it out the door. Also, ask for the suspension settings to be adjusted for your body weight.

Make sure you have at least the bare essentials for repairs and maintenance: spare tube, patch kit, tire levers, pump, multi-tool, chain lube and something to carry it all in. And, don’t forget a helmet. 

Many shops like REI provide a free first tune-up. Be sure you bring back your new bike to take advantage of that offer.