Instead its structure that consist a lot of spoke that carry a load, the material that use to make rims also important. Rim first made from wood. It is very uncomfortable and easy to break when put a heavy load on it. Nowadays, the rim is created with many type of material. Those are steels, aluminium, and also carbon.
Steel is heavy metal, so lot energy need to paddle the bicycle. Thus also if damaged can be difficult to pull back into shape. But because it's so strong it is quite difficult to bend in the first place and steel is cheaper than all the other materials. It is easy to rusted
Aluminum has greater use of bicycle rim. It can be made in any shape and profile, flat or aero. Aluminum also has light weight compare to steels. It has resistant on been rusted. Aluminum is easy to manufacture. Greater stiffness in an aluminum wheel requires the use of more material, adding weight and producing a rougher ride.
Carbon suitable for bicycle rim. It usually used at racing bicycle because its weight is light. Carbon's higher tensile modulus increases rim stiffness, which reduces power loss as the rider's energy is transmitted to the rear wheel.