In a mid-to-high-range bicycle, titanium stands as one material with its various benefits and negative aspects compared to other materials like aluminum and carbon fiber. Titanium bikes are gradually finding their niche in the market, which is prestigious enough to have them sold at really expensive prices. They are, therefore, increasingly being embraced by cycling enthusiasts. What sets it apart from aluminum and carbon fiber? Let’s look at the differences and see some pros and cons.
First, understand the general terms and concepts about metallic materials.
- Stress and Deformation
- Stress: The load per unit cross-sectional area (σ = Load / Area); basically, the weight that can be supported per unit area.
- Deformation: It could be elastic and plastic deformation.
Elastic Deformation: In that, when it gets stressed, it deforms but after the removal of stress goes back to its pre (initial) state.
Plastic Deformation: If the application of stress results in deformation, and the material is not able to get back into its original shape even after the applied stress has been removed.
- Elastic Modulus: Elasticity is in simple terms the degree of deformation. Materials with a high elastic modulus are stiffer and more resistant to deformation under load, while materials of low elastic modulus are softer and more deformed under load. There are places in bicycle construction that have to deform more and others less.
  Aluminum Alloy | 69-79 |
  Titanium | 116 |
  Titanium Alloy | 80-130 |
  Carbon fiber | 70-200 |
Young’s Modulus is the elastic modulus. The larger the value, the larger the elastic modulus. The following table gives Young’s Modulus for some of the materials with which bicycles are made.
It may be seen from the table that carbon fiber has the largest average elastic modulus and aluminum has the smallest. In this respect titanium is not remarkable. Let’s see other properties and make a full comparison.
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- Yield Strength and Tensile Strength
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Yield Strength: It is the limit of elastic deformation and also known as the yield point. Upon increasing the stress to a particular limit, the material results in plastic deformation; it ultimately bends.
Tensile Strength: This is the point that, on increasing the stress to a particular limit, the material not only undergoes plastic deformation but results in breaking down.
Materials Used In Bicycles | Tensile Strength | |
  6061(6000 series aluminum alloy) |   no heat treatment | >100 |
  heat treatment(T6) | >246 | |
  7005(7000series aluminum alloy) |   heat treatment(T6) | >345 |
  7075(Extra hard aluminum, aircraft alloy) |   no heat treatment | >230 |
  heat treatment(T6) | >597 | |
  CPTi(pure titanium)Heat treatment(T6)More pure titanium is used as follows:TT800 800.Grde4588~753,UTT75 753 | >597 | |
3-2.5T(3%8J-2.5V Ti alloy) | >685 | |
  6-4T(6%6J-4V Ti alloy) |   heat treatment | 1160 |
  no heat treatment | 980 |
3. Density
Density is the unit weight per unit volume. It is a very important consideration in the weight determination of the bicycle frame. If one wants to build a lightweight frame, this can’t be a data point that can be ignored. A low density doesn’t necessarily automatically translate to a lighter frame, though.
Materials Used In Bicycles | Density |
Aluminum Alloy | 2.6-2.9 |
Titanium | 4.5 |
Titanium Alloy | 4.3-5.1 |
Carbon fiber | 1.5-1.6 |
From the brief history that was given about titanium bicycles, it was the U.S. who first employed the use of titanium alloys in bicycle frames in the 1960s. It was considered that titanium alloys were “light and hard.” As a result of immature manufacturing techniques, early titanium frames could only select the relatively easier processing titanium alloys. Consequently, insufficient stiffness resulted in these frames being unsuitable for long-distance racing. Not applicable in all competitions, however, they were ideal in situations where lightweight bikes were required. Yet, some fans were so enthusiastic when early titanium bicycles appeared that they even changed all the screws to this material.
Given the impression of some people, titanium bicycles are not only expensive but also very rare. However, the cost of the material itself does not play the key role in creating such a high price of the bicycle. The complexity of the manufacturing process and the difficulty in processing titanium alloys make them more expensive. Basically, it is of light weight, high strength, and resistant to corrosion. Normally, it is applied in a specific environment. The pure titanium does not have adequate strength. Therefore, in current material processes, titanium was alloyed with aluminum, vanadium (Al, V) to form a kind of titanium alloy with higher elasticity compared to the aluminum alloy, which benefits the design capability. Similarly, as with the aluminum alloys, strength can be improved by heat treatment through aging processes.
All in all, titanium bicycles offer a singular combination of properties that appeal to targeted segments of the cycling community. While unlikely to ever be considered highly practical due to cost and application constraints, their unique properties-a particularly high stiffness-to-weight ratio and durability–make them appealing to cyclists desiring the ultimate experience.
Alloy |  Distinguish | strength of extension σb (MPa) |
Yield strength   00.2 (MPa) |
Elongation (%) |
Young modulus E(GPa) |
pure titanium | JIS Three | Â Â 480~620 | Â Â 345 | 18 | 105 |
Grade 4 | 550 | Â Â 480 | Â Â 15 | Â | Â |
PTT800 | 800 | Â | Â | Â | Â |
UTT75 | 750 | Â | Â | Â | Â |
3-2.5Ti | annealing | Â Â 685 | Â Â 590 | 20 | Â |
6-4Ti | annealing | Â Â 980 | Â Â 920 | 14 | 110 |
  Aging treatment | 1160 |   1100 |   10 |
Advantages of Titanium Alloy Frames:
Lightweight: Being one of the light metals, the “lightness” of titanium alloys is one of their most prominent features.
Corrosion Resistance and Rust Prevention: Titanium is almost never corroded in a general environment.
Great Riding Feel: Titanium is also used in the springs of shock absorbers. Titanium frames made nowadays are suitable for long rides. Some riders are fond of titanium frames, believing they offer an excellent riding experience. However, after comparing it with chromoly steel, some think that chromoly steel frames have better shock absorption and a superior riding feel. But chromoly steel’s biggest flaw is its susceptibility to rust, making it suitable only for mid-to-low-end bicycles. Should titanium tube processing technology improve in the future, it’s believed it could achieve a riding feel similar to chromoly steel.
Disadvantages of Titanium Alloy Frames:
The relatively expensive raw materials, combined with complex processing techniques, lead to a high price. Titanium exists in nature as titanium dioxide, and its extraction and processing are complicated, requiring high technical standards and time, thus increasing costs. Welding is also extremely difficult, requiring the use of inert gases with great care. The commonly mentioned TIG welding is a method using a tungsten electrode and argon gas for arc welding. Titanium welding must be performed in an oxygen-free environment. Due to these reasons, titanium frames are quite expensive.
Relationship between Titanium and the Environment:
Titanium has excellent corrosion resistance (used in nuclear-related applications), is not afraid of rain, injury, or water droplets that don’t need to be wiped clean. Using this material for bicycles may seem wasteful? However, titanium also has disadvantages, such as galvanic corrosion. When aluminum parts are joined with titanium parts, they can gradually corrode. Similar galvanic corrosion occurs with other metals, especially in the seat tube area. For example, if an aluminum seat tube is joined to a chromoly steel frame and left unchecked, the contact surface turns brown, and they may become inseparable.
Metal Fatigue
Bicycles and Fatigue: Titanium Frames: There are titanium frames with a thickness of 0.6mm by Panasonic. Additionally, the most famous American company in titanium frames, Litespeed, advertises that the fatigue life of their titanium alloy can reach five times that of aluminum and steel.
As cycling enthusiasts, riding a frame with walls processed to the limit to be thin and lightweight is acceptable. However, the more you ride, the more the strength decreases, and if you need to replace your bike every year, what’s the point of a light frame? Of course, professional riders are different as they have training bikes and competition bikes. The ability to maintain performance characteristics should be a criterion for selecting a frame.
Frame Appearance: Bicycles that rust easily are disliked. Despite careful maintenance, rust always occurs, causing pain to those who care for their bikes. Thus, people look for rust-resistant bicycles like those made of aluminum or titanium.
Aluminum Alloy (Al-Mg-Si, Al-Zn-Mg-(Cu))
Lightweight and affordable are its advantages. Aluminum alloys are alloys of pure aluminum with metals like Mg, Zn, Si, and Cu. Aluminum itself has advantages of lightness, good malleability, and corrosion resistance, and the addition of other metals significantly improves mechanical properties. After heat treatment (aluminum is heat-resistant and changes properties at high temperatures), various materials can be produced.
Alloy | Â 7005 | 7003 | 7075 | T6 |
Heat treatment | T53 | Â Â 0 | Â Â 0 | T651 |
strength of extension σb (MPa) | 345 |  |   230 | 597 |
Yield strength σ0.2 (MPa) | 305 |  |   107 | 526 |
fatigue strength | 130 | Â | Â Â 163 | 163 |
Elongation(%) | Â | Â | Â Â 17 | 11 |
Young modulus E(GPa) | Â | Â Â 74 | Â Â 74 | 74 |
Advantages of Aluminum Alloy Frames:
Lightweight Frames: Light but not very hard, so it’s made into an alloy and subjected to heat treatment in order to strengthen. Many aluminum alloy frames are made of 6061T6 material. The T6 mark means heat treatment and aging. Without the heat treatment, strength could be reduced to 1/2 or even 1/5.
Stability of appearance with time: While being a metal that rusts easily, when exposed to the air, aluminum forms a thin, very dense oxide film that prevents the further intrusion of air and water, thus preventing the continued rusting. In normal circumstances, the oxide film is almost colorless, hence changes in appearance are not easily noticeable.
Disadvantages of Aluminum Alloy Frames :
Aluminum is a low-modulus-of-elasticity material, and it is also low in stiffness. It has to be heat-treated; otherwise, it will not have sufficient strength.
Carbon Fiber (CERP)
Carbon Fiber (CERP): Frames of high-performance bikes are made from carbon fiber and are regarded as the finest for their lightness, stiffness, and great shock absorption. Carbon fiber is actually a composite material manufactured by embedding carbon fibers in resin. Its properties are amazingly lightweight yet directional, strong in tension, yet prone to breaking easily-overcome by layering thin sheets. However, this process of layering makes the production of a carbon fiber bicycle frame so labor-intensive that there are plenty of mistakes and inconsistencies in quality as skilled craftsmen become scarce. Besides, the quality of carbon fiber material itself might be seriously different from one manufacturer to another. Yet, despite all these challenges, carbon fiber frames offer certain unparalleled advantages not available with other materials, like the potential for manufacturing bicycles as light as 8 to 9kg. In particular, the lightness of a carbon fiber bike is felt while pedaling up a hill: the ride upwards is smooth and pleasurable.
Advantages of Carbon Fiber Frames:
The Light and High Tensile Strength: Carbon fiber frames derive their strength from the direction of the alignment of the fibers in relation to the stress placed upon it. The low density combined with high tensile strength makes the frames very light.
Excellent shock absorption: Carbon fiber is also utilized in the prosthetic limbs of athletes and special springs in many industries, for its shock-absorbing properties. It can be even used in bicycles without shock absorbers. However, quality may differ greatly among the different manufacturers.
Versatile Frame Design: Carbon fiber frames are produced by wrapping fiber sheets around molds and impregnating them with resin. This process provides designers with a plethora of frame shapes as well as other applications in the industry.
Cons of Carbon Fiber Bike Frames:
Loss in Strength: Although the carbon fibers are powerful in tension, concerning shear strength, they are fragile. This attribute demands the application of complicated calculation of stresses during manufacturing. As there are various manufacturing techniques, the quality differs accordingly.
Difficulty in modifying dimensions: The mold is once made, and changing the size of the frame is difficult. Molds are high cost and have to be shared across several products; hence, accommodating orders with different dimensions poses a problem.
Degradation over time: the resin used can degrade by sunlight, turning white in time. That is a matter of the producer’s technology, and one should not keep carbon fiber bikes exposed to direct sunlight.
Aluminum offers lightness, and carbon fiber is great in shock absorbency; meanwhile, titanium is not in the highest rank in any particular category but can be considered one of the more promising materials in the future.
Aluminum Bicycle Tubes: New generation’s designs seem to be pushing the envelope, as most are forgetting that aluminum does not have a fatigue limit. The wall thickness should be increased in order to decrease the level of stress; hence manufacturers prefer thin wall constructions with new alloys. Doing so may curtail the fatigue life of the frame. It seems that Al frames may evolve into a specialized application for racing competition as their performance would certainly diminish considerably with usage.
Titanium: The Metal of the Future?
There is, however, still room for development within the area of titanium frames, and their strength might surpass chromoly steel sometime in the future. Already, frames as light as 1.5kg have been made, and 1kg frames could be realized shortly, meaning that aluminum will lose the throne of the lightweight material. Yet another positive side of titanium is that it does not require painting, which reduces its weight even further. The chosen beta titanium alloy, Ti-15Mo-5Zr-3Al, is exceptional, as shown by the table below:
This is purely a theoretical discussion that invites cyclists to consider what the future of bike materials may hold. If the right alloy is used, titanium can be considered as the ultimate, but this remains a matter of further discussion and argument.
Alloy | PTT800(Pure Ti) | Ti-3AI-2.5V | Ti-6AI-4V | SCM415 | Ti-15mO-5Zx-3Ai |
strength of extension σb (MPa) |   800 |   685 |   1160 | >830 |   1470 |
Elongation (%) | >18 | >20 | >10 | >16 | Â Â 14 |