Mountain Bike Frames: So Many Out There...How do I Choose?

With all the mountain bike frames out there, does it really matter which frame I choose? Can't I get by with a cheap, low-end bike frame and then upgrade components later? And how do I know if the bicycle frame is the right size? Those were questions I asked when I was looking for a mountain bike so I am passing on what I have learned to you.

This site will provide information on...

  • strengths and weaknesses of different types of bike frame materials, including, aluminum alloy, steel, carbon fiber, and titanium so you can make an informed decision based on your riding needs when choosing a bicycle frame
  • tips on choosing the right mountain bike frame size so you know if the frame fits you properly

The frame is the foundation of your bike. You can add as many fancy parts as you want to a bad frame and it will still ride like a bike with a bad frame. Sort of like putting lipstick on a pig. That said, make sure you get a bike with a quality frame that fits you well and serves the purposes of what you want to do on your bike, whether it is riding scenic singletrack trails with some technical parts or mostly riding downhill doing jumps and steep drop-offs.


Closeout Prices on Bike Frames

Based on what you want to do with the mountain bike, you will be able to narrow down your bicycle frame selection to a hardtail, cross country, all mountain, freeride, or downhill frame. If you need more help figuring this out, check out the page on Types of Mountain Bikes and then click your back button to come back to this page.

Now that you have decided on what type of riding you are going to do, it makes it easier to figure out the type of mountain bike frame you want. If you are planning on an all mountain, freeride, or downhill mountain bike, you will be choosing a frame that has a rear shock built into it. If you are planning on cross country trail riding or racing, you may be interested in either a full suspension or a hardtail. If you are planning on a hardtail, you don't have to worry about the rear shock because they do not have one.

With all of the options out there, prices range between hundreds and thousands of dollars, so it's a good idea to set a budget of how much you are wanting to spend. The cost of the bicycle frame is mostly determined by the material and rear suspension, if it has one.

Frame Materials

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Mountain bike frames come in many different materials, which affect the weight, strength, and stiffness of the frame. The most common types of bicycle frame materials include steel, aluminum, carbon fiber, and titanium.

There are advantages, disadvantages, and cost differences of each material. Different ways of making the frame, such as heat treating, tube diameter, and butting, also affect the performance and cost of the frame.


Steel is affordable, durable, and easy to repair. Disadvantages of steel are that it is heavy and rusts easily. Two common steel alloys that are used to make mountain bike frames today include high tensile steel and chromoly steel.

High tensile steel is low cost and is often found in entry level bikes. This alloy makes a very durable frame, but it is heavy.

Chromoly steel has additives called chromium and molybdenum added to it, which is how it got its name. Chromoly is lighter than high tensile steel, but still heavy in comparison to other bicycle frame materials.

Sometimes, a bike will be made with a high tensile frame that has a chromoly seat post. Chromoly has been around for a long time. The cost varies based on whether the frame has parts that are heat treated and butted.


Aluminum alloy mountain bike frames are lighter than steel frames and do not rust. They are stiff and very commonly used for full suspension mountain bikes. Aluminum bicycle frames are not as strong as steel frames and cannot take as much abuse. They can crack if they are crashed or used for extreme riding with large drop-offs and jumps.

Aluminum frames have been around for a while, but not as long as steel mountain bike frames. There are many different aluminum alloys that are used or making bicycle frames. Like steel alloys, aluminum alloy bicycle frames are lower cost than carbon fiber and titanium mountain bike frames.

Carbon Fiber Frames

Carbon Fiber mountain bike frames are made of fibers of carbon held together by a very strong glue. They make very light frames that are rust resistant.

Carbon fiber frames can be made into many different shapes and designs because of the molding process. When building these mountain bike frames, the strength and flexibility can be controlled on different areas of the frame. This ability to fine tune the frame is a major advantage.

Because carbon fiber bike frames are very light, it is no surprise that they are great for road bikes, but there is controversy about their use in mountain bikes. Carbon fiber bikes are strong, but cannot take a lot of abuse.

A deep enough gouge will weaken the frame so that it will eventually crack open. Sometimes scratches or chips can be repaired at the bike shop, but the frame will never be as strong in that area as before. If the gouge is too deep, it is irreparable.

If you are buying a secondhand carbon fiber mountain bike frame, make sure it has not had previous damage.

Carbon fiber frames are more expensive than steel or aluminum frames.

Titanium Frames

Titanium bicycle frames are the lightest and strongest of all frame materials. Titanium frames are rust resistant, hard, and difficult to scratch. They usually are not painted, but polished to reveal their natural shine.

Titanium frames are very durable and will usually last a lifetime. The downside is that they are very expensive and above the price range for many of us.

Frame Fit

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One of the most important things to consider is the fit of the mountain bike frame. Fit is determined by many factors, including the length of the seat tube and the length of the top tube. For more information about how to determine whether a mountain bike frame fits properly, please visit our page on Mountain Bike Frame Size

For more information about fitting your mountain bike, including how to adjust your seat, handlebars, and suspension, please visit our page on Mountain Bike Fit

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