BIKE FRAME MATERIALS - Aluminum, Titanium, Chro-Moly...Does It Matter?


Mar 5, 2004


The Bottom Line Does It Really Matter? Oh Yeah!

Mountain biking is one of my favorite sports. I've been mountain biking (MTB) for over 12 years. I've mostly ridden in the Northwest: Washington, Oregon, Idaho, and Montana. But I've also ridden in Florida and Texas.

For me, finding the right bike is a very important process. It's much like choosing a car except more important in many ways, especially if you compete. Your bike will go through a lot with you (like a good pair of shoes for a runner) and it's important to find the right qualities so the experiences are efficient and fun.

A very basic consideration when looking at a bike is - "What's the price?" That is often the first question people have, especially beginners who don't necessarily know much about bikes. One of the major contributors to the overall price of a bike is the frame material. Other factors include suspension and components among other things.

It is important that the buyer - you - has a good idea of what the bike is going to be used for. If you're just riding with the kids on the weekend you can pass buy the titanium and carbon fiber frames and look at a low cost cro-moly bike. But if you've been training and you're looking for a bike you can race with then you have to take a closer look. Be honest with yourself though because bikes can cost a lot of money. The most expensive bike I've owned was a 2001 Specialized FSR Enduro Comp which I bought for $1,699. High-end bikes can easily break the $4,000 mark.

This review will probably be the most helpful for those that are budding MTB competitors.

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Frame material affects several characteristics of a bike. They are stiffness, weight, and strength. So it's important to get a proper mix of stiffness, weight, and strength that's is appropriate for your biking activities. Though most inexperienced riders won't really be able to tell a difference, with the exception of weight, until they've been riding for a while.

There are two major types of MTB racing - downhill and cross-country (XCR). Obviously, weight is not much of a factor for downhill racers where as weight is very, very important for cross-country racers. Other types of racing include dual slalom and trials.

There really is no "perfect" material though I think some might disagree with me. With that in mind, lets take a look at the different frame materials available...


Chro-Moly

Chro-moly is a fancy name for steel. Steel is heavy. But, steel is stiff. A frame made with chro-moly will usually have small tubes. To help reduce weight many steel frames have thin walled tubes. But remember, the thinner the tube walls are the less stiffness you'll have. If you're a heavy rider you'll want a thicker tube wall to support your weight. Reynolds 853 is usually considered the best type of steel for bike frames because it gains strength as it cools after the welding process. All steel has the same inherent stiffness.

Positives:
* Very Strong
* Stiff Ride
* Durable
* Cheap

Negatives:
* Heavy
* Prone To Rusting


Aluminum

Aluminum is one of the most common frame materials because it is light and fairly affordable. Aluminum provides the rider with a very stiff ride. Aluminum frames have large diameter tubes that help improve strength and stiffness. This material is often used for unique frame shapes.

Positives:
* Light
* Stiff
* Inexpensive
* Rust-Proof

Negatives:
* Less Strength Than Steel
* Can Break Under Heavy Use
* Difficult To Repair
* Thin Walled Tubes Dent Easy


Carbon Fiber

Carbon fiber frames are very strong and stiff. They are made by braiding fibers of carbon and affixing them with a very strong glue (epoxy). These kind of frames allow for unique frame shapes because they can be molded to the proper shape much easier than metal alloys. Carbon fiber can crack so watch out for that.

Positives:
* Great Strength
* Great Stiffness
* Very Light
* No Rust

Negatives:
* Expensive
* Prone To Breakage


Titanium

In my opinion, titanium is one of the best materials for any frame. It combines a great balance of lightness, strength, durability, and stiffness. The best alloys of titanium are as strong as the best alloys of steel frames. For a stiffer titanium frame look for larger tubes. Titanium frames usually come in two alloys:
- 3Al/2.5V alloy (3% aluminum / 2.5% vanadium)
- 6Al/4V (6% aluminum / 4% vanadium)

The 6Al/4V is stronger but more expensive.

Positives:
* Super Light
* Very Strong
* Rust Proof
* Great For Large Riders

Negatives:
* Very Expensive
* Somewhat Flexible (compared to steel)


Butt My Frame Sucka! - When looking at aluminum frames and some large diameter tubed steel and titanium frames you'll want to make sure that the tubes are butted. This increases strength and it's important.

What's Up With Flex? - Flex is when there is lateral movement in the frame. This most often happens with the tire but can also come from the seatpost. But there can also be flex in the frame itself. That is why stiffness is important. Be sure to ask about the flex characteristics of the bike you're looking at. Flex can steal power from your pedal stroke and, especially with full suspension bikes, is detrimental when riding uphill (crosscountry racing for example).

Ooh, It's So Stiff! - You sick-o I know what you were thinking! Stiffness refers to how much the frame itself absorbs vibrations and bumps in the surface you are riding on. Aluminum is notorious for offering a very unforgiving ride. Steel frames are known for being absorbant.

Who Designed This? - In addition to the frame material, what determines a lot as far as stiffness, flex, strength, and even weight is the design of the frame. I would recommend reading some reviews in MTB magazines. Also, since you're on Epinions check out some of the reviews. Frame design is very important.


Summary:

If you're doing cross-country (XCR) riding you'll want to get the lightest possible bike that has the least amount of flex. For downhill riders, focus on suspension travel, strength, and durability. Light frames and components are important for both, but even more so for XCR. I like aluminum a lot but I would love to be able to afford titanium! There are some nice carbon fiber bikes out there too!

My FSR Comp has an aluminum frame. My complaint about it is there's way too much flex in the rear swing arm for it to be a good XCR bike. The rear swing arm is the part attached to your rear tire, rear suspension, and bike frame.


Good Mountain Bike Companies:
* Specialized
* GT
* Trek
* Barracuda

And many more...


Final Say:

Be sure to research your purchase carefully!

Also, be sure you know what you and the bike will be doing, then focus on your price range. Obviously, try to get the best mix of quality components, suspension (if desired), and frame material. Other than that - have fun and enjoy your new ride!

Time to shred!




Over The River
And Through The Woods...

Thanks For Reading!





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