Bicycle rims are the metal or carbon fibre hoops that hold the tyres on your bike wheels. They are attached to the hubs by spokes, which provide tension and support. Rims have different shapes and sizes depending on your bike and riding type.
Rims are important for several reasons. First, they affect the performance and handling of your bike. For example, wider rims can accommodate wider tyres, which offer more grip and comfort on rough terrain. Narrower rims can reduce weight and aerodynamic drag on smooth roads. Second, they influence the durability and safety of your bike wheels. For example, stronger rims can withstand more impact and wear from bumps, crashes and jumps/drops. Third, they contribute to the aesthetics and style of your bike. For example, carbon hoops or colourful rims with flashy decals can add flair and personality to your ride.
When buying new rims for your bike wheels, there are some factors to consider:
Size: You need to choose rims that match the size of your tyres and tubes. The most common sizes for road bikes are 700c (622 mm diameter) and 650b (584 mm diameter). The most common sizes for mountain bikes are 29er (622 mm diameter), 27.5” (584 mm diameter) and 26” (559 mm diameter).
Width: You need to choose rims that fit the width of your tyres and tubes. The width of a rim is measured from one inner edge to another (inner width) or from one outer edge to another (outer width). The inner width determines how well a tire fits on a rim. The outer width affects the aerodynamics and weight of a rim.
Material: You must choose rims that suit your budget and preferences. The most common materials for rims are aluminium and carbon fibre. Aluminium is cheaper, lighter and more durable than steel but heavier than carbon fibre. Carbon fibre is more expensive but lighter than aluminium alloy but less durable than steel.
Brake type: You need to choose rims that match the brake type of your bike. There are two main types of brakes for bikes: rim brakes and disc brakes. Rim brakes use pads that squeeze against the sides of a rim to slow down or stop a wheel. Disc brakes use rotors that attach to the hub of a wheel and callipers that clamp onto them to slow down or stop a wheel.
Design: It helps to choose rims that appeal to your taste and style. There are different designs for rims, such as deep-section (which has deeper sides), shallow-section (which has shallower sides), box-section (which has flat sides), clincher (which has hooks that hold clincher tires), tubular (which has smooth edges that glue tubular tyres) etc.