Bicycle consists of multiple part groups – frame, that holds everything together, fork that absorbs impacts on the front wheel, drivetrain, wheel set, seat and seat post, stem and handlebar. Each part of bicycle holds an important role in bicycle structure and how the ride on the bike feels. Bicycle parts can cost from under dollar for smaller bolts to couple of hundred or even thousand dollars for large and expensive parts like frame and fork.
Each type of bicycle has different parts. For example bmx bikes have smaller frame and wheels, rigid fork, high rise bar, strong and heavy stem, only one speed, stronger cranks and rim brakes. In opposite, a mountain bike will have different type parts. Mountain bikes have larger frames, often made from aluminum alloy, suspension fork to absorb impacts on the front wheel, aluminum handlebar and stem, multiple speed gear with shifters, derailleurs and special chain guards. Mountain bikes usually have disc brakes instead of rim brakes, but also rim brakes are used on mountain bikes. Disc brakes are used more often, because they do not lose braking power in rain and mud. All bicycles, except special trail bikes used in sports, have seat and seatpost. Seat is chosen in matter of comfort level rider want. For cruising rider will choose softer and larger seat, for longer distances a more lighter and comfortable seat. For sports the lightest and durable seat possible, as there is no need for comfort. Handlebar and stem are also different for each bicycle type. Main type of handlebars used on most mountain bikes are aluminum alloy bars with little or no rase. Road bikes have special handlebars types called bull horns. On bmx bike you will see a high riser bar that is durable and made specially for racing and tricks. On bicycles used for downhill you may also see chromoy and carbon handlebars.
Frame and Fork
Bicycle frame is made from aluminum or chromoly. You will find aluminum frames on many mountain bikes and chromoly frames on bmx bikes. Frames comes in many different sizes, the size of frames is measured in inches. Bicycle frame manufacturers are making frames from size XS to XXL similar as with clothes. So if you are an average height person, you will need a M size frame. Forks are also made for different bicycle types. Some bicycles like bmx, roads, fixed gear and some mountain bikes will have rigid forks. Rigid fork do not absorb impact on front wheel, but allows rider to accelerate faster and do not waste so much energy while pedalling. Suspension fork is much more comfortable, but also more heavier. This means that suspension forks are not used in cycling sports, where bike weight plays an important role. Suspension forks comes with different travel lengths. Forks used for riding in city will have 60 – 80 mm travel and forks used on tracks, in woods or on mountain will have fork travel from 100 – 180 mm and more.
There are also multiple types of brakes. The most popular brakes on bmx and fixed gear bicycles are rim brakes. Rim brakes are braking bicycles rim with special rim brake pads. Mountain bikes mostly uses disc brakes. There are two types of disc brakes – mechanic and hydraulic. Mechanic disc brakes are the most basic version of disc brakes and are used on mountain bikes that do not need that much braking power. Hydraulic disc brakes works with oil pressure, similar as car brakes. Hydraulic disc brakes are used on high end mountain bikes. Hydraulic disc brakes can be found on most xc and downhill racing bicycles.
Wheels used on bicycle mainly differs in size. Smaller bicycles will have smaller wheels, as bmx, and larger bicycle will have larger wheels, as road and fixed gear bikes. Average wheel size for mountain bike is 26 inches, for bmx 18 inches and for road and fixed gear bikes up to 29 inches. There are also 29 inch mountain bikes or 29ers that are becoming more popular in past few years. Most types of bicycles used freewheel hub, but fixed gear bicycles uses fixed gear hub. Freewheel means that bicycle movement does not move cranks and pedals. Fixed gear hub means that movement of bicycles back wheel is also moving the cranks and pedals.