Strength
A measure of a metal's strength is the load it can hold before the metal yields and will not return to its original shape. As a metal, steel is stronger than aluminum. While increasing aluminum tube diameter and width compensates for its reduced strength, it will still generally be weaker than a steel frame. As a rider, this means a steel bike will uphold better under high loads and on rough terrain. This may be important for a heavier rider, for touring cyclists and others who use their bikes to transport cargo.
Stiffness
The stiffness of a metal refers to how much it flexes when put under a load. As a metal, steel is stiffer than aluminum. When riders refer to the stiffness of a bike, they talk about how much a bike gives both under the force of a pedal stroke and to the bumps on the road. A steel bike flexes more than an aluminum bike. This is because the tube diameter on a steel frame is smaller than that of an aluminum bike. To compensate for the reduced strength of aluminum, the frame tubes must be larger, which makes for a stiffer ride.
Weight
Looking at metal properties, steel weighs more than aluminum. This holds true with bike frames. While frame design can significantly reduce the weight, steel frames generally weigh more than aluminum frames. New technologies have reduced the weight of steel frames so the difference is not nearly as dramatic as compared to a 1970s steel frame. Some cyclists prefer the slight gain in weight in order to have more flex in their ride.
Article Written By Kathrine Cole
Kathrine Cole is a professional outdoor educator. She teaches rock climbing, backpacking, cycling, and bike maintenance classes. She is a graduate of the National Outdoor Leadership School, a Wilderness First Responder, and a Leave No Trace Trainer.
