Shift to the smallest chainring and smallest rear cog
Place the bike on a stand or flip it so the drivetrain is accessible
Gather supplies: degreaser, chain cleaner brush or old toothbrush, microfiber rags, chain lube, optional chain cleaning tool, gloves
Wipe off loose dirt with a dry rag
Apply degreaser to the chain (and jockey wheels/derailleur pulleys if needed)
Scrub the chain thoroughly with a brush, rotating the pedals backward to expose all links
If using a chain cleaning tool, fill with degreaser and run the tool along the chain while rotating the pedals
Rinse/wipe away degreaser with a clean damp rag (avoid soaking bearings)
Dry the chain completely with a clean dry rag
Inspect for remaining grime and repeat degreasing/scrubbing if necessary
Apply chain lube sparingly to the inner side of the chain on each link while rotating the pedals backward
Let lube sit briefly (a few minutes)
Wipe off excess lube with a clean rag to prevent attracting dirt
Spin the cranks to distribute lube and ensure smooth shifting
Test ride briefly and re-check that the chain is clean and not overly oily