Bicycle Check: ABC Quick Check
This is an easy way for you to remember what parts of the bike you need to check.
A is for air in your tires. Check everything to do with the tires, such as inflation, trueness, loose axle bearings, worn treads.
B is for brakes. Check if the levers are far enough from the handlebars; brake pads worn or in the correct position; are the cables working. Also check the headset (apply brakes, rock the bike back and forth); check the handlebars for looseness (hold the front wheels between the knees and try to twist the handle bars side to side, up and down)
C is for Chain. Check everything with the drive train: chain lubrication; pedals spin freely, derailleurs work; looseness in the bottom bracket.
Quick is for Quick release. Are the levers on tight, nuts on axles tight; levers flush against the forks.
Check is for a Final Check Over. Drop the bike from a few inches off the ground and listen for loose parts. Try your brakes as you ride off.