Tamircinin söylediği üzere zincir ölçer bisiklet bakımında kullanıldı.

Because tamircinin söylediği is a subordinate clause built with a -DIK form.

In this pattern, the subject of the subordinate clause usually takes the genitive ending:

• tamirci = mechanic / repairman
• tamircinin = the mechanic’s / of the mechanic

So:

• tamircinin söylediği = what the mechanic said / that which the mechanic said

This is very common in Turkish:

• öğretmenin anlattığı = what the teacher explained
• arkadaşımın yazdığı = what my friend wrote

Söyledi is a normal finite verb: he/she said.

But söylediği is a verbal adjective / participial form built from söylemek. Here it means something like:

• what he/she said
• that which he/she said
• the thing he/she said

So:

• tamircinin söylediği = what the mechanic said

The ending here is basically the -DIK participle plus a possessive marker:

• söyle-dik-i → söylediği

You do not need to translate it word-for-word every time, but it helps to recognize that this is a noun-like clause, not a main verb.

Here üzere means something like:

• as
• as stated
• in accordance with
• just as

So:

• Tamircinin söylediği üzere = As the mechanic said / As stated by the mechanic

This use is fairly formal or written-sounding. In everyday speech, learners may hear other options more often, depending on context.

Yes, it is very close to a set expression.

The pattern X-in söylediği üzere is commonly used to mean:

• as X said
• as X stated
• as mentioned by X

Examples:

• Doktorun söylediği üzere... = As the doctor said...
• Uzmanın belirttiği üzere... = As the expert stated...

So even though it is grammatically analyzable, it is also worth learning as a chunk.

They can overlap, but they are not identical.

• ... söylediği üzere = as stated by... / as ... said
  More formal, often written.

• ... dediği gibi = as ... said / like ... said
  Very common and natural in speech.

• ...e göre = according to...
  More like reporting a source or point of view.

So these are similar:

• Tamircinin söylediği üzere...
• Tamircinin dediği gibi...
• Tamirciye göre...

But the nuance is slightly different:

• üzere sounds more formal and structured
• gibi sounds more conversational
• göre emphasizes according to

Because bisiklet bakımı is a noun compound in Turkish.

• bakım = maintenance
• bisiklet bakımı = bicycle maintenance

In Turkish noun compounds of this type, the second noun usually takes a 3rd person possessive ending:

• bisiklet bakımı
• araba kapısı = car door
• ev çatısı = house roof

Then when you add the locative ending -da / -de, it attaches to that possessed form:

• bakımı + nda → bakımında

So:

• bisiklet bakımında = in bicycle maintenance / during bicycle maintenance

Because the noun already has a possessive ending:

• bakım-ı = its maintenance / maintenance-of-it (part of the compound)
• then locative: -nda

So the structure is:

• bisiklet bakım-ı-n-da

That -n- is a buffer consonant used after possessive endings before certain case endings.

This is why you get:

• evinde = in his/her house
• arabasında = in his/her car
• bakımında = in its maintenance / in the maintenance of it

It is a noun phrase meaning something like chain measurer, chain gauge, or chain checker.

• zincir = chain
• ölçer comes from ölçmek = to measure

In Turkish, forms like ölçer can name a device or instrument:

• something that measures

So zincir ölçer is a tool used to measure chain wear or chain condition.

This kind of formation is common:

• ısıölçer = thermometer
• ses ölçer = sound meter
• nem ölçer = moisture meter

Depending on writing style, such terms may appear as one word or two words, but the meaning is the same idea: a measuring device.

Kullanıldı means was used.

It is passive because the sentence focuses on the tool, not on the person using it.

• kullandı = used
• kullanıldı = was used

So:

• Tamirci zincir ölçeri kullandı. = The mechanic used the chain checker.
• Zincir ölçer kullanıldı. = The chain checker was used.

Turkish uses the passive a lot when the user/doer is unknown, unimportant, or simply not the focus.

It comes from kullanmak = to use.

Step by step:

• verb stem: kullan-
• passive marker: -ıl-
• past tense: -dı

So:

• kullan-ıl-dı = was used

This same pattern appears in many verbs:

• açıldı = was opened
• yazıldı = was written
• görüldü = was seen

Because Turkish normally places the main verb at the end.

So the sentence structure is very natural:

• Tamircinin söylediği üzere = As the mechanic said
• zincir ölçer = the chain checker
• bisiklet bakımında = in bicycle maintenance
• kullanıldı = was used

That final-verb pattern is one of the biggest differences from English word order.

Yes, Turkish word order is flexible, but the neutral/default order keeps the verb at the end.

For example, you could also say:

• Zincir ölçer, tamircinin söylediği üzere, bisiklet bakımında kullanıldı.

This gives a slightly different emphasis, but the meaning stays essentially the same.

Still, the original sentence sounds normal and natural.

Turkish has no articles exactly like English the and a/an.

So zincir ölçer can mean:

• a chain checker
• the chain checker

The exact interpretation depends on context.

Similarly:

• tamirci can mean a mechanic or the mechanic
• bisiklet bakımı can mean bicycle maintenance in a general sense

English translations must choose a or the, but Turkish often leaves that unstated.

Very roughly, yes — that is actually a useful way to think about it at first.

A literal breakdown is something like:

• tamircinin = of the mechanic
• söylediği = the thing that he/she said

So:

• tamircinin söylediği = what the mechanic said

That is not the best natural English translation, but it helps explain the grammar.

It sounds a bit formal or written, mainly because of söylediği üzere.

A more conversational version might use:

• tamircinin dediği gibi

So a more everyday-sounding alternative could be:

• Tamircinin dediği gibi, zincir ölçer bisiklet bakımında kullanıldı.

Both are correct; the original just sounds more polished or formal.