Crouch at the none-Drive side of the bicycle and grab the crank arms. Try to rock the crank side to side to identify lateral play in the bearings. Grab the pedals and try to do the same. You should not feel any play in these bearing.
Next select a gear on the front and rear derailleurs that gives you a straight chain line from the front cogs to the rear, once selected, rotate the cranks backwards. The cranks should rotate relatively freely without binding and the chain should not skip and catch on the sprockets.
Finally check that the sprockets do not have any missing teeth and that they are not twisted or bent and check that the front mech runs parallel to the chain rings and that it cannot be moved under pressure.
This is a visual inspection that can only be carried out effectively when the frame is clean Check along the head tube, top tube, down tube, seat tube, chain stays, seat stays, and around the bottom bracket feeling for dents and possible cracks. A cracked frame is a major safety issue and the bike should not be ridden if failures are found.
Saddle and post
Grab the bike by the saddle and first apply lateral pressure to ensure the seat clamp is properly tightened. Next apply vertical pressure to ensure that the bolts holding the saddle to the post are tight. You should not feel any play when carrying out this stage of the m check.
Check the alignment and tension on your quick release skewer it should be palm tight and pointing upwards or backwards. The wheel should sit centrally to the chain stays if the wheel does not align with the centre of your chain stays the quick release may not be seated properly and will need correcting.
Lift the back wheel off the floor and spin the wheel slowly. You will need to check the condition of the tyre and its tread. You’re looking for any cuts or foreign objects embedded in the tyre. The tyre should have tread or in the case of road bikes you should have a tread wear indicator. Look for small round dents in the tyre tread which are around 2-3mm in diameter. When these indicators disappear it is time to change the tyre.
Next you’ll need to check the spoke tension, the tension should be even over all of the spokes and should flex slightly when you grab and attempt to squeeze two spokes together.
Spin the wheel faster and check the true of the wheel. The wheel should be true the bearing should be smooth and the tyre should not bulge out from the rim at any point. The rim should not catch on the brake pads as the wheel rotates.
Make sure that the cage of the rear derailleur sits parallel with the rear cassette sprockets and that it is not bent or twisted.