Which Frame is for You?

By Curtis Henry

In the early days of modern bicycle racing in the 1970s, there was nothing higher tech or faster than a hand built steel frame made from Reynolds or Columbus tubing.   At the time, the focus on advancing the design of bicycle frames was limited by the available materials and the technology and the required to manufacture them. The thought of using such advanced materials like aluminum or carbon fiber was truly in its infancy, and the early attempts to use these materials produced unsafe and poorly made frames and forks.

However, as time and manufacturing technology progressed, so did bicycle materials and design. The current bike market is flooded with options, and can be an overwhelming process to navigate the myriad of choices. Regardless of what type of bike you are looking for, (Road, Tri or Mountain) your choice of frame material can be limitless, and each one has pros and cons depending on what’s important to you. Wither it is Steel, Titanium, Aluminum or Carbon Fiber, each material is unique and produces a uniquely different set of ride properties.
Steel

Steel

As the grandfather of frame materials, steel has the longest and most tested history of all the available options. Steel’s history dates back to the 13th century BC, and its discovery sparked a new age in human history as one of the building blocks of modern society. It has been extensively studied by thousands of engineers in every field of science and is accurately predictable in almost every one of its uses. From an engineering perspective, steel is by far the most tested material to build a bicycle frame from. Its characteristics can be accurately calculated, it can be easily manufactured, it has excellent ride properties, and it is extremely durable. Just as other frame materials have advanced, so has steel. Today’s modern steel tubing in thin and light and is blended with other metals to produce a stiff and strong tube. So why isn’t every bike made of steel?

Steel is limited to a relatively small amount shapes and designs and consequently has a limited capacity to produce exotic or aerodynamically shaped tubes. As aerodynamics play an in increasingly important role in frame design, steel seems to have reached its limiting factor. Because steel tubes are drawn or rolled into shape, the dimensions of the tubes must be symmetric and cannot be easily made into unique or non-prismatic shapes. Steel also is also somewhat limited by its weight, as it is the heaviest of the four main frame materials when compared dimensionally; that is when exact sizes are compared. However, because steel has such high tensile strength (pulling strength), a high modulus of elasticity (bending strength), and very high toughness, it can be made thinner and lighter when compared on a strength to weight ratio basis.

Although steel has a few limiting design factors when it comes to building a super aerodynamic and ultra-light frame, it does have some exclusive characteristics that can produce a beautiful and well riding frame for the right rider. Steel is one of the longest lasting and most durable materials available and has a very long fatigue life, which means you will be able to ride the same frame for as long as 30 years with the proper care. So if you’re looking for a bike to last you a lifetime of riding, it might be a good choice. Steel has unique ride characteristics and has often termed as having “soul." Because steel is somewhat “springy” and stiff at the same time, it does a great job of deadening the road buzz and vibration while still allowing you to “feel” the road or trail through the bike. So if you’re looking for a long lasting and durable frame, with excellent ride properties, and you are not too concerned with aerodynamics and weight, take a look at steel. You will find that is has a steadfast following of riders and is it truly an exceptional choice given the current trends in the bicycle world.

Aluminum

Almost as old as steel frames, Aluminum has come a long way from its early days as a great material for making Canoes and airplane parts. Originally conceived as an attempt to reduce the bicycle’s weight, manufacturers began to experiment with the lighter metal, and found that it was easy to work with and showed promise. The early aluminum frames were certainly lighter, but were built with relatively soft and smaller diameter tubes which were often lugged like many of the steel frames were. Because aluminum technology was fairly new and untested, these early frames were very soft, whippy, and often pretty scary to ride. Some of the early Aluminum frames from such companies as Vitus and Alan, were pretty scary to ride to say the least. I can attest to this, as my first road bike was an anodized Vitus with down tube shifters; it was a pretty sketchy bike and had a short lifespan, as aluminum is less durable than steel or titanium. Later Aluminum frame pioneers such as Cannondale and Klein figured out that an aluminum tube set needed to be oversized, and could be Tig welded to form a clean and strong weld which eliminated the lugged design. However, these early oversized tube frames were incredibly harsh, and soon created a reputation for aluminum as a terribly riding bike. Never the less, manufacturers began push the design and build capacities to accommodate the new material, and aluminum found its place in the available line-up of frame materials. However, it was not without its issues.

Today’s version of aluminum frames take full advantage to the manufacturing and building technology that has been developed over the decades of it history, and hove completely overcome many of it early problems. Aluminum has proven itself as both an inexpensive material for entry level bikes, as well as a boutique material for some mid to high end frames. Straight gauge (continuous tube wall thickness) tubes work very well for entry level bicycles in which the ride quality is not quite as important as the price and overall value. Whereas, a butted (tapering tube wall thickness) tube set frame is more tune-able, and can build into a very light and stiff frame that has excellent ride characteristics. By adding strategically placed sections of Carbon Fiber tubes and distinctive curves to specific sections of the frame, a high quality aluminum frame can have a ride quality better than many more expensive materials. So, if you are looking for a value oriented bike to get started into cycling with, take a look at aluminum. You’ll find that many of the stigmas of yesteryear's early frames are not true anymore, and aluminum is a versatile material that won’t break the bank.

Titanium

Regarded as the most exotic frame material in today’s current bike market, Titanium is rare and generally more expensive than steel or aluminum. Titanium was first discovered in the 1790s, but didn’t make its debut into the frame market until the 1970s when it struggled with many of the same issues that aluminum had.   Although titanium is found in nature as a pure element, its commercial and aerospace version is blended with aluminum and vanadium to aid in its manufacturing and to increase its strength. In terms of durability, there are only a few other materials that stack up to its incredible properties. Titanium is naturally corrosion resistant, which means it will never rust, discolor, or corrode even when subjected to extreme conditions. As a uniquely tough material, titanium can withstand more abuse than any other frame material, and works well for riders who are generally hard on their equipment or have a particularly corrosive chemistry to their sweat. Titanium has an exponentially longer fatigue life than all the other frame materials, which means that it can withstand the rigors of any cyclist for many decades of riding.

The idea behind a titanium frame is to meld the low weight of the aluminum tubes with the strength and ride of a steel frame. Over the years of its development, manufacturers such as Litespeed and Merlin have learned to produce light weight frames with butted tubes and a true blend of aluminum and steel in terms or its ride characteristics. Titanium retains much of the “soul” of a steel bike, and yet reduces the frame weight by as much as 1/3 of its heavier counterpart.    Its manufacturing process allows it be seam welded which means that it can be made into slightly more exotic shapes than steel, which aids in its ability to be shaped into a more aerodynamically shaped tube. So if you’re looking for a truly exotic and ultra high quality frame for decades of service, have a look at titanium. You’ll most likely find a customizable and incredibly riding material that is truly versatile as a road, mountain, or tri bike.

Carbon Fiber

By far the youngest member of the frame material line up, Carbon Fiber has the shortest and consequently least tested background. Because the material is a composite (made of two distinctly separate components) it is difficult and somewhat complicated to predict and test its behavior and fatigue life, relative to the other materials. Carbon Fiber found currently in the products you have seen and used is comprised of a “baked” carbon fiber which is usually woven into a fabric and impregnated with an epoxy resin. To build a part or tube requires the fabric to be shaped, pressurized, and baked to activate the epoxy resin glue. It is typically a lengthy process which requires a good deal of accuracy to produce a reliably high quality and durable part.   That being said, lets relate it to a bike frame.

The early versions of carbon bike were, believe it or not, built from graphite golf club shafts and carbon tubes and glued into aluminum lugs at the joints. With polished lugs and clear coated carbon tubes, the Graftek frame made by The Exxon Corporation (yes, the oil company) was a pretty unique innovation. However, these early carbon bikes had questionable ride quality due to frame stiffness issues and were not well received due to the cost and reliability. Many of these early versions of carbon frames and forks mimicked the size and shape of their steel counterparts, and quickly developed a reputation for being soft and under designed. Eventually, the science behind the new material progressed to a point where engineers were able to develop frames and components that were able to showcase the true nature carbon composite as a stiff and light material. Manufactures have progressed from a tube and lug design to a monocoque type design in which the joints and tubes are made as one piece and fewer glued joints are needed.

Fast forward to today and you’ll find that carbon fiber composite has made a distinctive impact on cycling design and has dynamically progressed cycling equipment into what it is at present. Almost every aspect of a current bicycle and its components has been revolutionized by the advent of composite design. No other event in the history of bicycles has made such an impact on aerodynamics, weight, and ride quality. Carbon is truly a versatile material in terms of how it can be shaped, tuned, and constructed. Manufactures can construct almost any shape from the raw material, and by modifying the lay-up of the final part with different types of fabric, the ride of the bike can be “tuned” for stiffness, comfort, or a mix of both. The fibers of the woven fabric do a great job of handling the stresses and loads that riding places on a frame while the epoxy deadens the road buzz and vibration.

Be warned however, carbon composites are not without fault. Because of the labor intensive aspects of the construction process a good quality carbon frame can be pretty pricey. With costs regularly in the $3000 - $4000 range, a good carbon bike is by far the most expensive option. Although the material itself is very durable, it handles the applied loading differently than other materials and is more susceptible to surface damage and cracking. Carbon composite does great job of handling loads spread across its surface, but is more susceptible to damage from point loads and surface scratching. Care must be taken to avoid clamping the tubes improperly or damaging the surface with scratches or gouges. Also, because the materials strength and stiffness are not linear in their performance, there is often a distinct difference between a cheap carbon frameset and one of higher quality.

Be careful when making a carbon frame purchase; a poorly tuned carbon frame can be a nightmare to ride, and is often worse than a cheap aluminum frame! On the other hand, a properly tuned composite frame should have excellent riding characteristics and will be both laterally stiff (side to side stiffness) and vertically compliant (up and down comfort). It is often better to avoid the carbon hype and allure of an inexpensive and cheaply made composite frame in favor of a higher quality and similarly priced aluminum or blended material frame. Be sure to do some research here, and you’ll find that you can immediately feel the difference between a cheaper composite frame and a good quality one. So if price is less of an issue and aerodynamics and weight are ultimately important, take a look at a carbon composite frame. You’ll find some sexy looking equipment, with some serious technology behind it!

Both a Master Cycling Mechanic and Mechanical Engineer, Curtis Henry is the owner of Cannon Cyclery. He can be reached at cannoncyclery@gmail.com or www.cannoncyclery.com