You want to treat yourself to a new bike but without breaking your piggy bank, the second-hand bike is a solution.
It is nevertheless advisable to make a small inspection tour before buying it and to evaluate the necessary repairs:Is it a stolen bike?Buying a second-hand bike on the internetBicycle inspection, tips & tricks to check frame, transmission, brakes, bearings, wheelsSpare parts price listFirst step: check that it is not a stolen bike!The invoice and the engraving of the bike will already allow you to detect if the seller is really the owner. Is the frame repainted? The price is abnormally low? The size of the bike and the seller do not match? Then, beware!Next, you’ll have to carefully check various sensitive points on the bike: the frame, transmission, brakes, bearings, wheels and peripheral components.Inspecting the bikeThe frameworkThe frame and welds must not be cracked;the condition of the paint will show the owner’s care and practice;be careful: your bike must be adapted to your size!The transmissionCheck that the sprockets and chain are in good condition. To do this, place the chain on the large chainring and gently pull it out: if you can see two teeth, it will be good for recycling! Note that the chain and sprockets (and even the chainrings in some cases) are always changed together;check that the derailleur(s) do not have too much normal play, in which case they will have to be replaced. Check the cable/gear chain assembly: if it is difficult to shift to the different gears, you will need to replace them. The same applies if they are chewed, oxidized, frayed… ;Finally, check that the shifters have their notches well marked (the little “click” you hear when shifting).BrakingCheck that the brake pads are always in good condition (the groove must be sufficiently marked) ;check that the cable/brake shoes assembly is in perfect condition: by pulling on the brake lever, you may or may not notice its flexibility. The brake shoes must not be chewed or oxidized;if it is a disc brake system, check that there is no air in the circuit (spongy brake lever), that the lining on the brake pads is thick enough (more than 2mm) and that the disc is not warped;Bearings: Track the game!At the bottom bracket: move back and forth outwards by pulling one of the cranks. If there is play, or if the bottom bracket axle does not rotate (the bearing is seized up), you will have to replace it;Steering: Apply the front brake by moving the bicycle back and forth. If you feel play (usually expressed by the onomatopoeia “klok klok”), it will be necessary to tighten it. Also, if you feel resistance when turning the handlebars, you may need to replace the headset bearings;at the wheels: make them move sideways (from left to right) with your hand. If you feel a flutter, if they do not turn freely or if you hear a cracking sound, you will most likely have to replace the balls and/or cones.The wheelsCheck that the wheels do not wobble and that there are no “jumps” in the wheels when you turn them;check that all spokes are still present and that their tension is correct (neither too much nor too little);check (in the case of rim brakes) that the rim flanks are not too hollow. Run your finger over the rim: if the indentation is too deep, you will have to replace the rim;check that the freewheel (which holds the rear sprockets) on the rear wheel is not too quiet, does not have too much play and transmits the power from the chain to the sprockets;worn or cracked tires will need to be replaced.