What you are about to read is proprietary to Full Moon Laboratory. It is a simple way to check if your bicycle is ready to ride. Kinda like a flight check a pilot does before take off.
And I arranged it alphabetically so no one goofs it up.
A is for Air pressure.
The most accurate way of doing this is to hook up a gauge to the valve and check the pressure. But, you can also check by pushing the palm of your hand into the contact patch of the tyre. NO pinching on the side wall.
B is for Brakes
Hold the handle bar of your bike while standing next to the bike and pull down on both brake levers, now try to push the bicycle forward, it should not. Now release the front brake and try pushing the bike forward, it should not. Now grab the front brake and release the back one and try to push the bicycle forward, it still should not move!
C is for change in direction
There is a chance that your stem bolts and head set bolts be be loose because of vibrations, standing next to the cycle, grab the bars and turn it side to side while checking if the front wheel is also turning corresponding to the movement of the handlebar. Now you know steering system is functioning properly or not.
D is for drop test
A drop test involves you picking up the cycle by the handle bar and the the top tube just under the seat, lifting the bike about 3-4 inches above the ground and releasing the bicycle to fall to the ground, if there are any parts of the bicycle which have loose bolts and are rattling, they will make an evident noise. By repeating this exercise multiple times, you can narrow down which part of the bicycle is affected and then fix it accordingly.
I recommend doing the A B C D test every time you start riding the bicycle, the more often you do these, the more attuned you will be to what is normal and therefore be able to identify the abnormal easily.