When people want to buy a used road bike they are often influenced by what they would look at when purchasing a second-hand car, such as checking the tires, which really doesn’t make sense in the world of cycling considering it is very easy to replace a worn tire.
In reality there are several components that can give us a clear and truthful idea of the wear and tear of a used road bike.
First of all it is important to check the braking track of the rims, especially if you are interested in only buying the wheels: wheels that look beautiful but whose braking tracks are worn down can simply be thrown away. Carbon wheels are often sold at fabulous prices on the internet, but more often than not the braking tracks are completely worn down. This can also be very dangerous: wear can break the rim causing the cyclist to fall with a 360 degree somersault over the handlebars.
In any case, the wheels may have been replaced, so we will now look at other features.
The second thing to inspect is the crankset: the foot rubs against the crankset and scratches it. This happens to more or less everybody, but surely a crankset with no external paint means that it has covered many kilometers. The wear of the crank teeth must also be examined.
You then obviously have to check the chain and sprocket set; remember it is always a good thing to replace them together in order to avoid a skipping bike chain. There are specific tools to check the lengthening of the chain. Having them would provide objective data on the kilometers covered by the bike chain.
Another thing that people often forget to do is inspect the brake/shift levers. Examining these carefully provides information not only on whether they have lost colour or clarity but also on whether the bike has crashed. The levers are the first thing that generally hit the ground. A small scratch may simply imply that the bike has been leant against a wall clumsily, whilst a larger scratch may imply that the bike has crashed.
Even a non-perfect alignment of the lower end of the handlebar is a sign of collision.
Another detail involves the rubbing of the brake/gear cable housings with the steering tube: if the owner has not had the foresight to protect them with transparent tape or rubber, the housings rub against the steering tube and can reveal the actual age of the bike.
Often the buyer checks the saddle, but in reality this is a component subject to severe wear and is frequently replaced. A more indicative feature, on the other hand, is the condition of the pedals; it is not important to inspect the paint of the pedals, which is easily removed, rather any dents or inclinations.
That said, buying a used product from a shop is always advisable. The shop is obliged to give a 1 year warranty by law, and therefore will sell the bike in the best possible condition, the safest. Avoid the “best deals” that can often be seen around: it is difficult to check everything, you may risk spending a much higher amount in mending the bike afterwards.