Bike frames are made from a variety of materials, the most popular being steel, aluminum, titanium, carbon fiber, and even bamboo. If you are looking for a new bike for commuting, running errands or adventure cycling to exploring new parts of the city, each choice has advantages and disadvantages for price, ride comfort, durability, style, and maintainability. While bike brands usually have standard materials they like to use for their bikes, if you look around you can usually find the bike style and frame material you prefer in a hybrid, road, gravel, mountain, or ebike. Which frame material is the best choice?
Steel Bike Frames
Chromoly steel is what is commonly used today in a steel frame bike because it is the more high-tech version of carbon steel. It’s lighter than carbon steel and equally as strong, although it costs a little more. Steel tends to be the least stiff of frames on the market, so it offers responsiveness and flexibility which translates into a comfortable ride. Pavement is seldom smooth in the city with pot holes and road debris common but a steel frame, due to its flexibility, can absorb shocks. A steel frame bike has been described as offering a “springy” ride making it comfortable for a long day in the saddle. Steel is denser, stronger, more durable and resistant to fatigue than aluminum, but if you do get into a crash and need a repair, it can be done by many local frame building shops. Steel is a popular material for ebikes due to its strength.
If you want a custom-made bike, steel is usually the choice of hand-made frame builders because it is easier to work in a small manufacturing facility. You can use thinner walled tubes enabling the design of vertical flex into a bike. For mass production, steel is more expensive to manufacture than aluminum which it why it is less common on lower end models.
You may be familiar with the steel frame bikes produced in the 1960s with thick, heavy tubes that were designed to make the bike practically indestructible. That is why there are so many vintage Schwinns and Raleighs still around today. Modern steel bikes are nothing like these--chromoly steel is lighter and the tube interior is thinner but just as strong. It may be hard to tell just by looking at a bike what the frame material is, although they usually have a sticker at the bottom of the seat tube. One way you can verify that a bike frame is steel is to hold magnet to it.
Disadvantages of steel bike frames are that although relatively light, it is still heavier than aluminum and steel can rust if not well maintained.
Aluminum Bike Frames
The most common bike frame material is aluminum because it is fairly light, affordable, and corrosion resistant. It is used on both recreational, mountain, and race bikes because it has a high amount of strength compared to its weight. Improved manufacturing processes have resulted in budget friendly prices. In fact, some brands offer the same geometry and components of their higher priced models just swapping out the carbon fiber or titanium frame with an aluminum one for a lower price. Aluminum frames are in good supply and are a good choice if you are looking for a light, strong, solid ride.
The disadvantage of aluminum is that compared to steel it is stiffer, which means less shock absorption and less comfort for riders. It’s not ideal for bikes that are going to be ridden on dirt roads or long distance touring, where the rider is spending long hours in the saddle. Other disadvantages are that it is more difficult to repair and aluminum fatigues more quickly over time.
Titanium Bike Frames
Titanium is a like steel with additional desirable features such as being lighter weight and corrosion-proof. Although it is not as flexible as steel, it is more flexible than aluminum and carbon fiber and has good shock-absorbing properties. The smooth ride and durable qualities make it popular choice for high end road and mountain bikes. Failure of a titanium frame is rare which is why you find many titanium frame makers offering lifetime warranties against manufacturing defects. But even if it should break in a crash, it is easier to repair than aluminum or carbon fiber, although not as easy as steel. Because it does not rust, you do not need to paint it.
The disadvantage of a titanium bike frame is that it is labor intensive to fabricate and because it is relatively rare and pricey, a titanium bike frame will be more expensive that other options.
Carbon Fiber Bike Frames
The process for manufacturing carbon fiber was invented in 1963 and it was initially used in aerospace, civil engineering, and military applications, but it was later adapted for bicycle frames along with other uses. Carbon starts out as fibers woven into sheets. These sheets are combined with a glue-like resin and shaped into any desirable form. The advantage of a carbon fiber bike frame is that is the lightest of all materials, corrosion free, and stiff. It can be repaired but it must be in a facility with specialized equipment.
The price of a carbon fiber bike is dependent on the grade of the carbon used, how efficient and automated the manufacturing process is where it was fabricated, and the complexity of the design. It is popular on high end road and mountain bikes and is used on virtually every bike being raced at the professional level.
With carbon fiber you can make shapes not possible with other materials giving designers flexibility for innovative designs, aerodynamic features and comfort. For example, you can make a high stress area like the bottom bracket stiffer but allow for more flexibility in the seat stays, thus the frame has different properties - stiff where it needs to be and more flexible where that would be beneficial. It can give a smoother ride than aluminum.
Disadvantages are its failure rate, which traditionally has been higher than steel or aluminum, although advances in engineering have reduced this as a risk. It is not as durable as steel and, like aluminum, is prone to dings and damage. Although cost of a carbon fiber frame has come down it is still more expensive than other materials.
Bamboo Bike Frames
There are specialty brands that have been building bikes out of bamboo for years. They claim the manufacturing process is more sustainable and materials are easier to recycle than any other. You will not have a complete bike made from wood, they often incorporate carbon-liners for stiffness and carbon or titanium forks and dropouts. Bamboo frames can be stiff, durable and comfortable, but are not as durable, with a life span of 10-15 years.
A traditional steel or aluminum frame bike is the most popular bike for city riding because it offers a smooth ride on a durable frame at a good price that will stand the test of time. Combine one of these frames with a good set of medium width tires, quality components, and a rear rack and bike bags and bike lights and you will ready to zip around town with a smile on your face. Is there anything more fun than this?
Earth Rider Blog about Cycling
Sharon Kaminecki and others comment on adventures in bicycling and other stories