Concepts

Cycling concepts you should know about - do the homework and search for the details

Drivetrains

Chains: speeds, direction, quick link, half link, lubrication, chain rotation, checking wear, shortening

Bottom brackets: types (square taper, JIS vs ISO; ISIS/Octalink; Hollowtech I-II, Campagnolo UltraTorque/PowerTorque), shell width and thread types, PressFit, tools

Chainline (43.5 mm road, 50mm MTB...)

Chainrings: BCD - bolt circle diameter; direct mount, frame devices, clearance

Front derailleur: mounting, min/max teeth, top/down/both pull, trim

Rear derailleur: min/max teeth, cable pull (actuation ratio), cage length, pulleys, limit screws, Shimano clutch, manufacturer cross compatibility