Ettersom dekktrykket er lavt, starter sykkelverkstedet serviceettersynet.

Here ettersom introduces a reason, so it works like since, as, or because.

Compared with fordi, ettersom often sounds a little more formal or written. In many everyday situations, both are possible:

• Ettersom dekktrykket er lavt, ...
• Fordi dekktrykket er lavt, ...

In this sentence, ettersom is simply a subordinating conjunction introducing the reason clause.

Norwegian makes compounds very freely, much more than English does. So dekktrykk is a single compound noun:

• dekk = tire
• trykk = pressure

Together, dekktrykk means tire pressure. Then the definite ending is added, giving dekktrykket = the tire pressure.

Dekktrykket is the definite form, meaning the tire pressure. Norwegian often uses the definite form where English also uses the.

In this sentence, the pressure is treated as a specific, known thing: the tire pressure of the bike being checked. So dekktrykket sounds natural.

Compare:

• Dekktrykk er viktig. = Tire pressure is important. (general)
• Dekktrykket er lavt. = The tire pressure is low. (specific)

Because dekktrykk is a neuter noun. In Norwegian, predicate adjectives often agree with the gender and number of the noun.

So:

• en bil → bilen er lav
• et trykk → trykket er lavt
• dekkene → dekkene er lave

Since dekktrykket comes from et dekktrykk, the correct form is lavt.

This is because of Norwegian V2 word order in main clauses. The whole first clause Ettersom dekktrykket er lavt takes the first position, so the finite verb in the main clause must come next:

• Ettersom dekktrykket er lavt, starter sykkelverkstedet serviceettersynet.

If you remove that first subordinate clause, the normal order is:

• Sykkelverkstedet starter serviceettersynet.

So the subject is not missing or inverted randomly; this is a regular word-order rule.

For the same reason: it is a compound noun.

• sykkel = bicycle
• verksted = workshop / repair shop

Together, sykkelverksted means bicycle workshop or bike repair shop. The ending -et makes it definite:

• et sykkelverksted = a bike workshop
• sykkelverkstedet = the bike workshop

In Norwegian, compounds like this are normally written as one word.

Because it refers to a specific inspection or check, not just any inspection. The base noun is et serviceettersyn, and the definite form is serviceettersynet.

This follows the same pattern as the other nouns in the sentence:

• sykkelverkstedet = the bike workshop
• dekktrykket = the tire pressure
• serviceettersynet = the service inspection / the service check

English uses a separate word the; Norwegian usually adds the definite ending to the noun.

Because Norwegian usually marks definiteness by attaching an ending to the noun:

• et verksted = a workshop
• verkstedet = the workshop

So in this sentence, the meanings of the bike workshop, the tire pressure, and the service inspection are built into the noun forms themselves.

A separate article can appear too, but usually when there is an adjective:

• verkstedet = the workshop
• det nye verkstedet = the new workshop

Starter is the present tense of starte. In Norwegian, the present tense often corresponds to English starts, is starting, or sometimes even a near future meaning depending on context.

So starter here is simply the normal present-tense verb form.

Yes. In Norwegian, it is standard to put a comma after a subordinate clause when it comes first:

• Ettersom dekktrykket er lavt, starter sykkelverkstedet serviceettersynet.

If the subordinate clause comes last, there is usually no comma before it:

• Sykkelverkstedet starter serviceettersynet ettersom dekktrykket er lavt.

So the comma matches the sentence structure.

Yes, absolutely. You can say:

• Sykkelverkstedet starter serviceettersynet ettersom dekktrykket er lavt.

That is also correct. When you do that, the main clause keeps normal subject-verb order: sykkelverkstedet starter.

So both versions are grammatical; the original just puts the reason first for emphasis or flow.