When buying a bicycle, do you ever wonder "how long will this bicycle last?"

When considering how long something will last, there are the terms "lifespan" and "useful life."

Although similar, please note that they refer to different things.

Lifespan and Useful Life

First, let's confirm the terms "lifespan" and "useful life."

Lifespan can also be rephrased as "durability period."

It refers to the period from when a product is bought new until it breaks down and can no longer be ridden.

Naturally, the more you ride it, the shorter its durability period will be.

It also increases or decreases depending on the storage conditions.

On the other hand, "useful life" is a legal term.

It refers to the depreciation period.

It is the period during which you can receive tax deductions legally after buying a bicycle.

The statutory useful life is two years.

By the way, new cars have a useful life of 6 years, and used cars have 4 years.

This is information that is usually not needed at all, but it is the value of a bicycle that you only consider when you need to think about how much a bicycle is worth, for example, after an accident.

To determine how many years it will last, consider its durability period.

When thinking about the lifespan of a bicycle, you should consider its "durability period."

It can be considered that the period until something critical goes wrong and it can no longer be ridden as a vehicle is its "durability period" and "lifespan."

Bicycle deterioration is not caused by the frame.

Now, let's consider what goes wrong that causes a bicycle to become unusable.

Conversely, by taking good care of those parts that tend to fail and performing maintenance, you can extend its lifespan and ride it for a longer time.

Unfortunately, there was no data found on how long it takes for a bicycle to become unusable.

Therefore, the following information is a general overview.

The general durability period of a bicycle is 4 to 5 years.

However, looking at each part of a bicycle, as mentioned in other articles, aluminum frames can typically be used for 5 to 10 years.

Carbon also easily lasts 10 years.

Depending on how it's used, it can last much longer, so the bicycle doesn't become unusable due to problems with the frame.

Just to be clear, the difference between an aluminum frame and a carbon frame is not in strength.

Generally, the strength of materials is compared using "tensile strength."

Test pieces are prepared and pulled from both sides, and the breaking strength is determined by the force at which the test piece fractures.

Carbon steel like chromoly is 400 N/mm2.

Aluminum is 80 N/mm2, and carbon is 15 N/mm2.

In terms of strength, steel is overwhelmingly strong, followed by aluminum, and then carbon.

One of the properties that indicates the toughness, which is the strength of a material, is the coefficient of linear thermal expansion.

Iron is 12.0, aluminum is 24.0, and carbon is 12.0.

Incidentally, the unit is 10-6/℃.

To explain toughness in an easy-to-understand way, it's fragility.

A wire bends easily when force is applied.

Materials like this are described as having low toughness.

Conversely, something like a Japanese sword, which is sharp, hardly bends up to a certain force, but breaks cleanly if more force is applied.

Would it be easier to understand if I described it as not bending but easily breaking?

Materials like this are described as having high toughness.

Iron and carbon do not bend to a certain extent and are relatively strong materials.

However, if a certain amount of force is applied, they suddenly fracture.

Compared to that, aluminum might be described as a softer material, but it is a material that won't suddenly break because it is relatively easy to bend to some extent.

Even if the toughness of iron and carbon are relatively similar, comparing their densities, which is the weight of the same size material, iron is 7.8, aluminum 2.7, and carbon about 1.75.

Carbon is overwhelmingly lighter.

If there was a frame of the exact same shape and iron weighed 7.8 kg, an aluminum frame would weigh 2.7 kg, and a carbon frame would only weigh 1.75 kg.

The characteristic of a carbon frame is that it is overwhelmingly light, but not as prone to bending as iron.

Reasons why bicycles break down

When you ride a bicycle for a long time, the parts that break down are limited to a certain extent.

From here on, my personal opinion will become stronger, but I will tell you which parts tend to break down.

One is the "chain."

It constantly engages with the gear (sprocket) and transmits the force applied to the pedals to the tires.

Therefore, if maintenance is neglected, it will rust, break, or deteriorate.

Regular oiling can make it last longer.

It is recommended to clean it to some extent and then oil it.

Second is the "sprocket."

Many people also call this a "gear."

If maintenance is neglected, it will also rust, which can contribute to the bicycle's demise.

In addition, the "derailleur" also deteriorates.

If it gets hit while riding or rusts, it will need to be replaced.

Since it is somewhat expensive, it often becomes a target for replacement with a new one.

Summary

It is good to consider the durability period of a bicycle to be about 4 to 5 years.

And the causes can be attributed to the chain, sprocket, and derailleur.

By performing maintenance, you can expect your bicycle to last 10 years.