The easy part: You’re ready to buy a new bike. (Great!) The confusing part: You realize there are multiple frame material options, and you’re not sure which to choose. Generally speaking, there are four main options: aluminum, carbon fiber, titanium, and steel. Each has pros and cons, but depending on your budget and intended use, we can help you find the right choice.
Is weight a priority? How much money can you spend? Do you want it to last for 10 years? Or will you replace it after a season or two? Are you planning to buy a big brand bike from your local bike shop? Or are you after something a little more unique, maybe even a custom build? The answers to all these questions will factor into your decision-making matrix.
If, for example, you’re a cash-strapped aspiring road racer, an aluminum frame likely makes the most sense, as they are relatively light, stiff, and affordable. Carbon fiber ticks those same performance boxes (and often does a better job of absorbing road buzz), but it’s more expensive. Conversely if you’re looking for the ideal long-distance touring bike and money is no object, a titanium frame is arguably your best option due to its silky smooth ride quality and resistance to the elements. Steel is less expensive and delivers a smooth ride, but it’s generally heavier than the other three materials and doesn’t last as long.
“There’s no one perfect material,” says Aaron Barcheck, founder and lead builder for Boulder, Colorado-based Mosaic Bespoke Bicycles, which primarily builds custom steel and titanium road, gravel, and cyclocross bikes. “All the frame materials do some things really well, but there’s also going to be tradeoffs.” And that’s why it’s important to understand their various properties. Here’s a primer.
The most common bicycle frame material, aluminum is known for being corrosion resistant, fairly light (though typically not as light as carbon fiber), and having a high strength-to-weight ratio. It’s also reasonably affordable, making it a popular choice for riders and racers on a budget. Most high-end carbon fiber models from the big cycling companies like Trek and Specialized offer aluminum models with the exact same geometry and components at a significantly lower price point.
“As a bike builder, it is easier to work with,” Barcheck explains. “That helps keep costs lower. It’s also typically stiff and responsive, making it good for criterium racing bikes because it accelerates quickly and delivers snappy handling.”
The downside is that stiffness often means a harsher ride quality because it doesn’t absorb road buzz as well as the other frame materials. Translation: It’s not ideal for bikes that are going to be ridden on dirt roads or long distance touring, where comfort is of prominent importance.
It’s also tricky to repair, and aluminum fatigues more quickly over time. Thus, the best application of aluminum tends to be in entry level road and mountain bikes, which often costs $1,000 to $2,000 less than carbon frames with similar components.
By far the most commonly used frame material for higher-end mountain and road bikes (including virtually every bike being raced at the professional level), carbon fiber is a composite of carbon sheets that are bonded together in a mold using resin. The primary advantage of the material is that at a given stiffness, carbon fiber is significantly lighter than aluminum, steel, or titanium.
This lower density also means carbon frames do a better job of absorbing (rather than transmitting) road vibration, which translates into a more comfortable ride. And carbon fiber can be formed into complex shapes, giving bike makers greater creative design latitude. This is especially useful when trying to maximize the aerodynamic efficiency of a frame.
“With carbon, you can make shapes that just aren’t possible with other frame materials,” Barcheck says, adding that by varying the alignment of the individual fibers, bike makers can engineer different amounts of stiffness in different areas of the bike depending on need. “For example, you can make high stress areas like the bottom bracket stiffer, but allow for more compliance and flex in the seatstays, which improves comfort. And because it’s not a metal, carbon fiber is more corrosion resistant.”
But that creative flexibility comes with a price. Although their cost has come down some in recent years, carbon fiber bikes are typically the most expensive. These frames are also more prone to fracture than metal, and once that happens carbon becomes fragile, and thus unfit to ride.
Another frame material popular with custom bike builders, titanium shares many of the same properties of steel, but has a greater resistance to corrosion and fatigue (it has the highest strength-to-weight ratio of all metals). That means you can build long lasting, lightweight frames. No wonder many titanium frame makers offer lifetime warranties against manufacturing defects.
Titanium is also renowned for its smooth ride quality that’s on par (if not exceeding) carbon fiber, making it an especially popular choice for custom road, touring, and hardtail mountain bikes. It’s also easier to repair than aluminum or carbon fiber, so if it ever does break, it can be fixed.
“In my opinion, it’s the best material because it’s so versatile,” Barcheck says. “It can be really light and stiff, but still do a great job of soaking up road vibrations. I also find it to be a little snappier than steel, so it’s a touch more performance oriented. It also doesn’t corrode so there is no paint needed, which helps shave weight.”
The downside is that titanium is a relatively rare (and thus expensive) material that’s labor intensive to work with, meaning these bikes are typically quite pricey.
Once upon a time, steel was the bike-building material of choice. But its mainstream use has waned in recent years, with carbon fiber and aluminum frames now far more prevalent on bike shop floors. The primary reasons for steel’s decline: weight and cost. It’s heavier than both aluminum and carbon fiber, making it less desirable for high-end bikes. And it’s more expensive to mass manufacture than aluminum, hampering its use on lower end models.
But it might be the perfect material for someone who wants a custom bike without the high price tag of titanium. Indeed, it remains a popular material for custom builders, who revere it for its ride smoothing characteristics (especially for touring bikes). The reason for this is that steel is easier and less expensive to work with than carbon fiber, and it’s also denser and stronger than aluminum. That means you can use thinner walled tubes, and thus design vertical flex into a bike.
Steel is also very durable, highly resistant to fatigue, and unlike carbon fiber and aluminum, can easily be repaired. “I love it for road and cyclocross bikes,” Barcheck says. “It just has an awesome, almost springy ride feel that’s really comfortable on long days in the saddle, or when you’re spending a lot of time on bumpy terrain because you can build in a lot of compliance. The downside is that it can rust. So if you live on a coast, you have to take a little extra care so it doesn’t corrode.”
As bike-packing and bike-touring grow in popularity, steel may make a comeback as a great material. If it breaks mid-trip, there’s almost always a welding shop that can help you put it back together or bang out a dent in the frame.
Bamboo + More
We won’t get into the other options too deeply here, but wooden bikes are no joke: Brands like Boo and Calfee have been building bikes out of bamboo for years, and while crashes can be costly, the frames are sturdy, lightweight, and surprisingly durable.
Alloys are popular in frame-building as well. Chromoly—chromium-molybdenum—is another common frame material used on many lower-end department store bikes. It’s a chrome-alloy steel that’s lighter than plain steel while maintaining the flexibility that makes steel a great material to use for frames.
Lastly, you may hear about scandium frames occasionally: They were popular in the early aughts, though now they’re hard to find. Easton Sports introduced scandium as a cycling-friendly tubing material, and for a while, it was everywhere: Ridley, Redline, Rock Lobster and Kona all had scandium cyclocross frames in their lineup years ago.
Scandium is mixed with aluminum in order make it stronger, but fell out of favor after only a few years on the market. Rumors around its fall from grace include a marketing issue because it was not well-understood compared to aluminum, or a knockoff problem that resulted in a bad reputation after the poorly-welded cheap frames began to fall apart. Now, many bikes that are made with an aluminum alloy contain small amounts of scandium, but you likely won’t see it prominently mentioned.
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