Bisiklet bakımında iç lastik değiştirildi.

Because bisiklet bakımı is a noun compound meaning bicycle maintenance or bike service.

• bisiklet = bicycle
• bakım = maintenance, care
• bakım-ı = the compound form used in bisiklet bakımı

Then the locative ending -da/-de is added to that whole compound:

• bisiklet bakımı → bisiklet bakımında

The n is a buffer consonant that appears before the case ending after this kind of ending.

So:

• bakımda = in maintenance / at maintenance
• bisiklet bakımında = in/during the bicycle maintenance

Here it means something like:

• during the bike service
• in the course of bicycle maintenance
• while the bicycle was being serviced

It gives the context in which the action happened. It does not mean the maintenance itself changed; it means the replacement happened as part of that maintenance.

İç lastik literally means inner tire, but in normal English this is usually inner tube.

In bicycle vocabulary:

• iç lastik = inner tube
• dış lastik = outer tire / tire

So even if the literal words look a little unusual, this is the standard Turkish term.

Because değişmek and değiştirmek are different verbs.

• değişmek = to change, to become different, to be changed on its own
• değiştirmek = to change something, to replace something

Here the inner tube is an object being replaced, so Turkish uses değiştirmek.

Then it is put into the passive:

• değiştirdi = he/she/they changed it
• değiştirildi = it was changed / it was replaced

So iç lastik değiştirildi means the inner tube was replaced.

Yes. It is a passive form.

You can break it down like this:

• değiştir- = replace / change something
• -il- = passive
• -di = past tense

So:

• değiştirildi = was changed / was replaced

This is very common in repair, maintenance, and service language, where the person doing the action is not important or is left unstated.

Because in this sentence iç lastik is not the object anymore; in the passive sentence, it functions as the grammatical subject.

Compare:

• Active: Usta iç lastiği değiştirdi.
  = The mechanic replaced the inner tube.
  Here iç lastiği is the direct object, so it takes accusative -i.

• Passive: İç lastik değiştirildi.
  = The inner tube was replaced.
  Here iç lastik is the subject of the passive sentence, so there is no accusative ending.

Because that is the normal Turkish sentence pattern. Turkish typically puts the finite verb last.

So the order here is:

• Bisiklet bakımında = during the bike service
• iç lastik = the inner tube
• değiştirildi = was replaced

This is very natural Turkish word order.

Yes, that is also possible.

Both are grammatical, but the emphasis changes slightly:

• Bisiklet bakımında iç lastik değiştirildi.
  More naturally sets the scene first: During the bike service...

• İç lastik bisiklet bakımında değiştirildi.
  Puts more focus on the inner tube.

Turkish word order is flexible, but the verb usually still stays at the end.

Because Turkish does not normally use articles like English a/an/the.

Whether English translates it as:

• an inner tube
• the inner tube

depends on context.

In a service note like this, English often uses the inner tube was replaced, but Turkish just says iç lastik değiştirildi.

Yes, but it means something slightly different in tone.

• bisiklet bakımında = in bicycle maintenance / during the bike service
  This is a standard noun compound and sounds very natural.

• bisikletin bakımında = in the maintenance of the bicycle
  This is more explicitly possessive and can sound more specific.

In many everyday contexts, especially short service-style statements, bisiklet bakımında is the more natural choice.

Yes, very much so.

It sounds like a brief maintenance note or service record entry. Turkish often uses short passive sentences in this kind of context, for example:

• Fren balataları değiştirildi. = The brake pads were replaced.
• Zincir temizlendi. = The chain was cleaned.
• İç lastik değiştirildi. = The inner tube was replaced.

So the style is concise and practical, just like a workshop or maintenance log.