Used to be called as hangers, bike bottom brackets are the axis that let the crankset rotate efficiently. A bottom bracket is composed of a spindle and bearings. These parts are enclosed inside a bottom bracket shell that connects other parts in a bicycle frame other than bike drivetrain components.
Bike bottom brackets are commonly classified according to its design and size. There is that so-called bottom bracket types and interface types. The bottom bracket type is made up of an axle and a group of equally-made bearings intended to make the pedaling action more efficient. The three-piece bike bottom brackets, loose bearing, cartridge bearing, Ashtabula, Thompson and external bearings fall under this type. Another set of bike bottom brackets called the interface brackets are produced to connect the crank arms to other parts of the bottom bracket. Shimano, Truvativ initiated the creation of bike bottom brackets that acquiesced to the requirements of the International Splined Interface Standard. In general, ISIS aims to create parts and bike single tools that will match immediately with the rest of the bike models. It also aims to create a more durable taper interface.
As a principle, higher prices of bike bottom brackets may mean higher quality as well. Light but durable materials may cost higher than regular models. It is also helpful to compare prices, features and compatibility of other products. FSA, SRAM and Truvativ also feature more advanced breakthroughs every now and then. There are also models with specialized lightweight aluminum materials designed for specific heavy duty purposes like dirt jumps, skate parks, mountain biking and racing. Remember that brackets are not the same as bike cargo racks so please keep that in mind.