This diagram and the
detail photos below it, show what the parts of a modern road bicycle
are called. Knowing the bike component names (nomenclature) and how
to correctly identify them will help you when you need to explain
something to a mechanic working on your bike, when you’re shopping
for upgrades and when you’re talking about bikes to other cyclists.
Another excellent resource is Sheldon
Brown’s bicycle glossary.
Hidden by the crankset in this picture is the bottom bracket.
There are actually two bottom brackets.
You call the bearing
assembly that the crankset spins on, the bottom bracket (marked A
in the photo; the mechanic is holding the end of the bottom bracket
axle that runs through the frame and that the crankarms attach to).
Mechanics and cyclists often say “BB” instead of bottom
And you also call the
part of the frame that the