To help reduce weight many steel frames have thin walled tubes, which lessen the overall stiffness. Some of the positive characteristics of steel are that it’s very strong, provides a stiff ride, durable, and cheap. Its negative characteristics are it’s heavy and prone to rusting. Aluminum is one of the most common frame materials because it is light and fairly affordable. Aluminum provides the rider with a very stiff ride and is often used for unique frame shapes. Aluminum frames have large diameter tubes that help improve strength and stiffness. The positive characteristics of Aluminum are, it’s light, stiff, inexpensive, and rust proof. Some of Aluminum’s negative characteristics are, it has less strength than steel, can break under heavy use, it’s difficult to repair, and it’s thin walled tubes dent easy. Carbon fiber frames are very strong and stiff. They are made by braiding fibers of carbon and affixing them with a very strong glue or epoxy. These kind of frames allow for unique frame shapes because they can be molded to the proper shape much easier than metal alloys. Its positive features are its great strength, its stiffness, it’s very light, and it doesn’t rust. Some negative aspects of Carbon fiber are it’s expensive and it’s prone to breakage. Titanium combines a great balance of lightness, strength, durability, and stiffness. The best alloys of titanium are as strong as the best alloys of steel frames. Titanium frames usually come in two alloys: 3A/2.5V alloy 3% aluminum / 2.5% vanadium or 6A/4V alloy 6% aluminum / 4% vanadium, being stronger but more expensive. Titanium is super light, very strong, rust proof, and great for large riders. However, Titanium is very expensive and somewhat flexible compared to steel