El chip de cronometraje es tan ligero como el dorsal.

Because tan ... como is the pattern used to compare adjectives and adverbs.

• tan ligero como = as light as
• tan rápido como = as fast as

By contrast, tanto/a/os/as ... como is used with nouns:

• tanto peso como = as much weight as
• tantos kilómetros como = as many kilometres as

So here, since ligero is an adjective, tan is the correct choice.

De cronometraje means for timing or used for timing.

It is a very common Spanish structure:

• noun + de + noun

So:

• chip de cronometraje = timing chip
• literally, chip of timing

Spanish often uses de where English prefers a noun used like an adjective.

Similar examples:

• gafas de sol = sunglasses
• tarjeta de crédito = credit card
• zapatillas de running = running shoes

It uses es because ser is normally used for characteristics, definitions, and general descriptions.

Here, ligero describes a quality of the chip:

• El chip es ligero = The chip is light

That is treated as a characteristic, not a temporary state or location.

Compare:

• es ligero = it is light in weight / it has that quality
• está ligero would sound unusual here

So es tan ligero como el dorsal is the natural choice.

Because ligero agrees with el chip, which is masculine singular.

Agreement in Spanish:

• masculine singular: ligero
• feminine singular: ligera
• masculine plural: ligeros
• feminine plural: ligeras

Since the subject is el chip, the adjective must match:

• El chip ... es tan ligero...

If the noun were feminine, it would change:

• La pulsera es tan ligera como...

Loanwords in Spanish are often assigned a gender, and chip is normally treated as masculine: el chip.

There is not always a deep logical reason; sometimes gender follows usage rather than a strict rule. In modern Spanish, especially in technology and sports contexts, el chip is the standard form.

So you would usually say:

• el chip
• un chip
• este chip

In Spain, el dorsal often means a runner’s race bib or bib number.

It originally relates to something worn on the back or associated with a number in sports, but in race contexts it commonly refers to the numbered bib you wear during an event.

So in this sentence:

• el dorsal = the race bib / bib number

This is a very common sports term in Spain.

Because dorsal here is a specific noun, and in Spanish it normally takes the article:

• el dorsal

After como, Spanish still keeps the article when needed:

• tan ligero como el dorsal = as light as the bib

You are comparing the chip with the bib, not with the abstract idea of bib.

Compare:

• Es tan grande como la mesa = as big as the table
• Es tan rápido como el coche = as fast as the car

Not very different in this sentence. Spanish and English line up quite closely here:

• El chip de cronometraje = The timing chip
• es = is
• tan ligero como = as light as
• el dorsal = the bib

So the structure is very natural and direct.

One small difference is that Spanish often uses de + noun where English uses a noun as an adjective:

• chip de cronometraje instead of
• timing chip

Yes, if the context already makes it clear which chip you mean.

• El chip de cronometraje is more specific.
• El chip is shorter and works if everyone already knows you are talking about the race timing chip.

So both are possible:

• El chip de cronometraje es tan ligero como el dorsal.
• El chip es tan ligero como el dorsal.

The longer version is simply more precise.

Yes. Ligero is the normal and natural adjective for light in weight.

For example:

• una mochila ligera = a light backpack
• un reloj ligero = a light watch

You may also see liviano, but ligero is generally more common and more neutral in everyday Spanish, including Spain.

So tan ligero como el dorsal sounds perfectly natural.