Learn Hardcore Turkish: Bisiklet zinciri yağlanmalı; yoksa bisikleti sürmek zor olur. - The bicycle chain must be oiled; otherwise riding the bicycle becomes difficult.

yağlanmalı means must/should be oiled or needs oiling. It is the necessity form of the passive verb yağlanmak:
• yağla- (root: “to oil”)
• -n (passive suffix → “to be oiled”)
• -malı (necessity suffix: “must/should”)
By vowel harmony, since yağlan- has the vowel a, the suffix appears as -malı (not -meli).

Why is it bisiklet zinciri and not something like zincir bisikleti or bisikletin zinciri?

bisiklet zinciri is a common compound noun meaning bicycle chain. Turkish often forms such compounds by:
• putting the first noun without a suffix: bisiklet (“bicycle”)
• adding the 3rd-person possessive suffix -i to the second noun: zincir-i (“its chain”)
→ bisiklet zinciri (“the bicycle’s chain” → “bicycle chain”).
You could also say bisikletin zinciri (using the genitive -in + possessive -i) to emphasize “the chain of that bicycle,” but the compound is shorter and more idiomatic.

Where is the subject in Bisiklet zinciri yağlanmalı? Why isn’t there a pronoun?

Turkish often omits subject pronouns when the meaning is clear. Here, bisiklet zinciri (“the bike chain”) is the subject of yağlanmalı (“must be oiled”). In passive constructions the object of the active verb becomes the (nominative) subject, so no extra pronoun is needed.

What role does yoksa play, and how does it compare to using the conditional suffix -mazsa?

yoksa means otherwise or or else, linking two clauses:
Bisiklet zinciri yağlanmalı; yoksa bisikleti sürmek zor olur.
You can express the same idea with a negative conditional:
Bisiklet zinciri yağlanmazsa, bisikleti sürmek zor olur.
Here -mazsa = -maz (negative) + -sa (if) = “if it isn’t oiled.” Both forms show that without oiling, riding the bike becomes difficult.

How does the infinitive bisikleti sürmek function in this sentence?

Adding -mek/-mak to a verb turns it into a noun (infinitive):
• bisikleti (accusative: “the bicycle”) + sürmek (“to ride/drive”)
= bisikleti sürmek (“riding the bicycle”).
This infinitive phrase acts like a noun (the subject of zor olur).

Why is sürmek used for riding a bicycle, rather than binmek?

• sürmek is used with vehicles (cars, bikes, horses) meaning to drive/ride.
• binmek literally means to mount/get on and is common with animals or public transport (bus, train).
With bicycles, native speakers say bisiklet sürmek.

What is the construction zor olur, and why use the aorist olur instead of a future form like zor olacak?

zor olmak means to be difficult.
• olur is the aorist tense, often used for general truths or a future-sense consequence: becomes/is difficult.
Using zor olur expresses a general result, while zor olacak (“will be difficult”) sounds more specifically future.

Why does the sentence use a semicolon before yoksa, and could it be a comma or period instead?

A semicolon shows a close link between two independent clauses, similar to English. In informal writing you could also write:
• Bisiklet zinciri yağlanmalı, yoksa bisikleti sürmek zor olur.
• Bisiklet zinciri yağlanmalı. Yoksa bisikleti sürmek zor olur.
Choose comma or period based on formality and clarity.