How to Choose a Mountain Bike


Mountain bikes have smaller frames and wider tires than traditional bikes. See pictures of extreme sports.
©iStockphoto.com/hamurishi

People have been modifying bicycles to handle difficult terrain for decades, while competitive mountain biking competitions date to the 1970s and 80s [Mountain Bike Hall of Fame]. Today, numerous manufacturers produce bikes specifically designed to tackle tough terrain and rigorous riding. The options available can seem staggering, from frame geometry to suspension, brakes and tire tread patterns.

A mountain bike differs from a road bike (commonly known as a "ten-speed" bike) by having a smaller, more rugged frame along with wider tires that can handle muddy tails, rocks and fallen branches and even jumps or steep climbs. The narrow, lightly treaded tires on a road bike may be efficient for high-speed riding on a smooth surface, but even the most gentle forest trail can give them problems.

Of course, mountain bikes aren't restricted to mountains. A durable bike able to handle wide variations in terrain might be ideal even if you ride cross-country or in an urban area. Whether you're planning long weekend rides, daily commutes or an all-out downhill assault on the steepest mountain around, this article will offer some crucial advice on finding the right mountain bike for you.

Choosing the Right Style of Mountain Bike

Not every mountain bike is used in the same way, so the exact bike you want depends heavily on what you plan to use it for. As a general rule, the more aggressively you plan to use the bike, and the more difficult the terrain you plan to ride over, the more advanced features you'll want on your bike. Of course, there's the corollary of that rule: More advanced bikes are more expensive. You'll find the perfect bike for you at the point where your needs and your budget intersect.

Choosing a mountain bike is a constant compromise between features, weight and cost. For example, a titanium frame is light and strong, but pretty expensive. A front suspension adds weight and cost, but is very advantageous on many terrain types. A full suspension (both front and rear suspensions) adds more cost and weight, but may only be useful to the most hardcore riders. (Take a look at How Mountain Bikes Work for more information on suspensions.) One thing all serious mountain bikers will tell you: Don't buy a low-budget mountain bike at a big box store or online. They may be cheap, but they're a waste of money. Expect to spend at least $400 -- and you may have to compromise on quality. In fact, some mountain bikers spend more than that on their wheels alone.

Another factor to consider is the amount of time you're willing to spend on bike maintenance. Bikes with suspensions and other advanced components have additional opportunities for mechanical failure, which some riders might consider a disadvantage compared to simpler, though less effective designs.

Size is very important. Sizing a mountain bike seems more like an art than a science. You have to consider your height, the amount of clearance between your crotch and the top tube, whether you'd prefer to sit upright or leaning forward (which in turn depends on how you plan to use the bike) and the length of the cranks. The simplest sizing advice is to never buy a bike until you've taken it for a test ride at your local bike shop. If it needs adjusting, they can help, and if it just isn't the right size, they can suggest a bike with a better fit.

In the next section, we'll help you frame your choice of bike by picking the best chassis for the job.

Choosing the Right Mountain Bike Frame

If there's one area of your bike you don't want to cut corners on, it's the frame. The reason is simple -- you can easily upgrade gearsets, brakes and other features, but you can't really upgrade the frame without basically buying a new bike.

The two aspects of mountain bike frames to consider are material and geometry. Here are the most common frame materials, along with their pros and cons.

  • High-Tensile Steel. This material is inexpensive and strong, but very heavy. This is used on low-end bikes, and serious mountain bikers won't touch it.
  • Chromoly Steel. A different alloy (using chromium and molybdenum) than high-tensile steel, it's lighter and more rigid, but costs a bit more.
  • Aluminum. An aluminum frame is lighter than chromoly, but not quite as strong. A well-made chromoly frame is better than a cheap aluminum one. Aluminum is a good compromise between weight and cost for intermediate bikers.
  • Titanium. This material is very light and strong. However, welding titanium is tricky, so some titanium frames have a reputation for broken joints. The cost of titanium frames has come down considerably, but is still mostly found in high-end, expensive bikes.
  • Carbon fiber. While extremely light and rigid, carbon fiber is very expensive and prone to impact damage. Carbon fiber frames are for serious competitive mountain bikers.

The higher-quality frames undergo a process called butting, in which the walls of the frame tubes are thinned in the middle, with thicker tube walls at the ends. This saves weight and makes welded joints stronger. You may see frames described as double or triple butted. Non-butted frames are known as straight-gauge.

The frame geometry you choose will depend on whether you want a rear suspension and how advanced a rider you are. Beginners and many intermediate mountain bikers do well with traditional diamond frames. To accommodate a rear suspension, you may need more exotic type of frame geometry, and competitive riders may prefer exotic geometries to save weight or increase performance.

It is also recommended that you get a frame with mounting spaces for optional equipment. A basic mountain bike can be upgraded easily as long as the hubs are able to mount disc brakes and the front suspension can be changed. If you want to take your bike for longer rides at some point, mounting spaces for mudflaps and cargo baskets will come in handy.

One last note: Look for a sloping top tube (the tube that runs from the seat to the front of the bike). Almost all mountain bikes have them, since they provide extra clearance for the rider in the event of a crash. Don't take it for granted, though. One painful encounter with a top tube will instantly remind you why sloped is better.

How do you keep a mountain bike under control during steep descents or while negotiating trail obstacles? We'll talk mountain bike suspensions in the next section.

Choosing the Right Mountain Bike Suspension

The bike's suspension helps keep the tires in contact with the trail, which lets the rider stay in control over obstacles like roots and rocks.
The bike's suspension helps keep the tires in contact with the trail, which lets the rider stay in control over obstacles like roots and rocks.
©iStockphoto.com/craftvision

A rigid frame bike has no suspension. It's actually difficult to find a rigid frame mountain bike, although a few manufacturers do offer one or two rigid models. Even low-end mountain bikes usually come with a front suspension, also known as a suspension fork. A bike with a suspension fork but no rear suspension is known as a hardtail. If a bike has both a front and rear suspension, that's known as a full-suspension bike.

Which is the right one for you? Each suspension element adds complexity and weight to the bike. A suspension fork trades this for increased control and comfort. A rough ride can take a toll on your wrists and arms if they're absorbing every impact. The control aspect is even more important. Without a front suspension, the bike's front tire will have a tendency to bounce off of obstacles like rocks or branches. When your front tire is bouncing, you can't steer. Plus, if you hit something on an angle, it can send your front tire bouncing to either side. That can lead to serious crashes. Unless you plan to ride exclusively on groomed trails or bike paths, a good suspension fork is crucial.

We've mentioned front suspensions, but do you need a rear suspension? Not necessarily. A rear suspension adds more weight, and requires a different frame, which makes it difficult or impossible to add a rear suspension to a hardtail bike. You could add a shock absorber to the seat post, which will add comfort but won't help you stay in control in rough terrain, which is really the point of a suspension. Many mountain bikers swear by rear suspensions -- in fact, they're the standard for competitive riders.

This leads to the question: Which type of rear suspension is the right one? Mountain bike rear suspensions have undergone extensive development in the last 20 years. They are difficult to design because the suspension is not just affected by impacts with obstacles, but also by the rider's weight, plus acceleration and deceleration forces. The unified rear triangle (URT) design common several years ago is now falling out of favor, as it tends to react poorly to acceleration, and becomes almost entirely ineffective if the rider stands on the pedals. Most bikes today are made with a raised low pivot (RLP) design, which uses an independent swingarm. There are endless variations on the basic RLP suspension, with each manufacturer developing its own particular type. Only experience and test rides will tell you the type that will work best for you.

Now you're hurtling down a mountain trail on your bike. How do you stop? Find out in the next section.

Choosing the Right Mountain Bike Brakes

The bicycle brakes you're most familiar with are rim brakes. You pull the brake lever on the handlebar, and a cable transmits that pull to a pair of brakes pads that squeeze against the rim, slowing the bike. There are a couple of different versions of this technology (some terms you might hear include U-brakes, V-brakes, direct pull brakes or caliper brakes). They all do pretty much the same thing and have the same limitations.

There are two main problems with rim brakes. First, the brakes make contact at the outer edge of the rim. If conditions are wet or muddy, it's very easy for the rims to get slippery. Obviously this can seriously affect the performance of the brake. Second, braking power is inherently limited by the small surface area the brake pads have to grab on to. If you're taking a downhill trail at high speed, there's no way rim brakes would have the braking power to slow you effectively.

The more advanced option is a set of disc brakes. These function just like disc brakes on a car. The hub holds a metal disc that normally spins freely along with the wheel. The fork has a caliper that squeezes the disc when the brakes are applied, slowing the bike. Disc brakes work better than rim brakes for a few reasons:

  • They're farther away from the trail than the outside edge of the rim, so they're less likely to pick up mud or water.
  • Braking power at the center of the wheel translates to greater overall breaking power because of the difference in speeds between the center and outside edge of the wheel.
  • You can build larger discs and calipers for more braking power.

Disc brakes sometimes add weight to a bike, but some companies have engineered advanced disc brake systems that weigh less than rim brakes.

You can also choose between mechanical and hydraulic disc brakes. Mechanical brakes squeeze the calipers with the same force that you squeeze the brake lever. Hydraulic brakes use hydraulics to amplify the force, resulting in even greater braking ability.

While the frame, suspension and brakes might be some of the most important parts of a mountain bike, they certainly aren't the only parts. What about the tires, gears and safety equipment? That's coming up next.

Choosing a Mountain Bike Saddle

While you're out shopping for a mountain bike, don't forget to spend a little time finding the perfect bike saddle. Your safety could depend on it.
While you're out shopping for a mountain bike, don't forget to spend a little time finding the perfect bike saddle. Your safety could depend on it.
©iStockphoto.com/marcosborne

A mountain bike's saddle cannot be overlooked. The tires provide contact between bike and trail; the saddle is the key point of contact between bike and rider. It supports some of the rider's weight and also provides lateral control. The wrong kind of seat can cause discomfort over long rides and reduce the rider's ability to effectively control the bike.

To find the right seat, you first have to consider two important parts of the seat: the pads and the nose. The pads are the rearmost portion of the seat; this is where most of your weight will rest when you're sitting back on the seat. Specifically, the two bony protrusions of your pelvis known as the ischial tuberosity (or sitting bones) bear your weight when you're in a seated position. Make sure these bones are actually resting on the pads. If your pelvis is too wide for the seat, the sitting bones will extend beyond the edges of the pads. Soft tissues will end up bearing your weight, which isn't very comfortable. Women tend to have wider pelvises than men, which is why companies offer saddles specially designed for female riders.

The nose can be a source of discomfort if the seat is not adjusted properly. However, it serves an important function, allowing the rider's thighs to exert lateral control over the bike. There are alternative saddle designs that omit the nose, but serious riders wouldn't consider them. If you focus on long cross-country rides, then comfort may be a more important factor than control.

The best way to find the right saddle and adjust it properly is to take it on a trail (wearing your usual biking clothes). A spin around the bike store parking lot won't tell you much about a saddle. Luckily, some bike shops offer test saddles that can taken on trails for real testing. There's definitely trial and error involved, but eventually you'll find the saddle perfectly suited to your riding style and body shape.

For more information on mountain biking and other outdoor sports, take a look at the links on the next page.

Related HowStuffWorks Articles

Sources:

  • Hopwood, Troy. "Buying your first mountain bike." Dirtworld.com, June 4, 2004. Accessed Feb. 15, 2010.http://www.dirtworld.com/TipsAndTricks/TipsStory.asp?id=35
  • Langton, Mark. "Choosing the right bike." MountainBikeSkills.com. Accessed Feb. 15, 2010.http://www.mountainbikeskills.com/choosing_bike.htm
  • Mountain Bike Hall of Fame. "The History of Mountain Biking." Accessed Feb. 15, 2010.http://www.mtnbikehalloffame.com/page.cfm?pageid=4
  • VanIngewen, Myra. "A beginner's guide to buying a mountain bike." Accessed Feb. 15, 2010.http://www.myra-simon.com/bike/mtb-advice1.html