Vites teli çekilince arka aktarıcı hareket ediyor.

Çekilince comes from:

• çek- = pull
• -il- = passive suffix, giving çekil- = be pulled
• -ince = when / once / as soon as

So çekilince means when it is pulled or once it is pulled.

This -ince form is very common in Turkish for when X happens, Y happens.

Because çekilince is passive: when it is pulled.

• çekince would mean when he/she/it pulls
• çekilince means when it is pulled

In this sentence, the cable is not doing the pulling; it is the thing being pulled. So the passive form is the natural choice.

Compare:

• Vites teli çekilince... = When the gear cable is pulled...
• Vites telini çekince... = When someone pulls the gear cable...

Those are close in meaning, but the grammar is different.

Because vites teli is a very common Turkish noun-compound pattern.

In Turkish, when one noun describes another noun, the second noun usually takes a compound ending:

• vites = gear
• tel = wire / cable
• vites teli = gear cable

This is the same pattern you see in things like:

• kapı kolu = door handle
• araba kapısı = car door

So teli here is not saying his/her cable. It is part of the compound structure.

Because these are two different structures:

1. vites teli

This is a noun + noun compound:

• vites = gear
• tel = cable
• compound form = vites teli

In this structure, the second noun gets a compound ending.

2. arka aktarıcı

This is adjective + noun:

• arka = rear / back
• aktarıcı = derailleur / transfer mechanism

Since arka is acting like an adjective here, there is no extra compound ending on aktarıcı.

So:

• vites teli = noun compound
• arka aktarıcı = adjective + noun

Because in this sentence it is not a direct object in an active clause.

In Vites teli çekilince, the verb is passive: çekilince = when it is pulled.
So vites teli is the thing affected by the action, and in Turkish passive structures it appears without the accusative here.

If you made the clause active, you would normally use the accusative:

• Vites telini çekince... = When someone pulls the gear cable...

So the difference is:

• vites teli çekilince = passive
• vites telini çekince = active, with definite object

The subject of the main clause is arka aktarıcı.

The sentence breaks down like this:

• Vites teli çekilince = When the gear cable is pulled
• arka aktarıcı hareket ediyor = the rear derailleur moves / is moving

So the thing that moves is arka aktarıcı.

The first part is a time/circumstance clause telling you when that movement happens.

Yes, Turkish word order is flexible, but this order is very natural.

A common Turkish pattern is:

[time/condition clause] + [main clause]

So:

• Vites teli çekilince = when the gear cable is pulled
• arka aktarıcı hareket ediyor = the rear derailleur moves

You could rearrange it for emphasis, but this version sounds neutral and natural, especially in explanation or description.

Literally, it is something like is doing movement, but you should learn it as the fixed expression hareket etmek = to move.

So:

• hareket etmek = to move
• hareket ediyor = is moving / moves

This is a very common Turkish pattern where a noun combines with etmek to make a verb.

Other examples:

• yardım etmek = to help
• kontrol etmek = to check
• fark etmek = to notice

So don’t translate it word-for-word every time; treat hareket etmek as one unit.

Both are possible, but they feel slightly different.

• hareket ediyor often sounds more immediate, descriptive, or like you are explaining how something works right now
• hareket eder sounds more general, habitual, or textbook-like

In technical explanation, Turkish often uses the present continuous form in a way English learners may find broader than English is moving.

So here hareket ediyor can still describe a general mechanical fact, not only something happening at this exact second.

Not always exactly. Depending on context, -ince can mean:

• when
• once
• as soon as
• sometimes something close to if in practical explanations

So çekilince could be understood as:

• when it is pulled
• once it is pulled
• as soon as it is pulled

In a mechanical sentence like this, all of those are quite close in meaning.

Because Turkish does not have articles like English the and a/an.

Turkish often leaves nouns bare, and the exact meaning comes from context.

So:

• vites teli can mean the gear cable or a gear cable
• arka aktarıcı can mean the rear derailleur or a rear derailleur

In a sentence about how a mechanism works, English usually uses the, but Turkish does not need a separate word for that.

Yes. That is a very good way to think about it.

Vites teli çekilince is a subordinate clause meaning something like:

• when the gear cable is pulled

It sets the condition or time for the main clause:

• arka aktarıcı hareket ediyor

Turkish often uses verb endings like -ince instead of separate words such as when plus a full finite clause.

So instead of building the clause the way English does, Turkish packs the meaning into the verb form itself.