هيكل الدراجة نظيف.

In present-tense Arabic nominal sentences, there is usually no written or spoken word for is.

So:

هيكل الدراجة نظيف
literally: the bicycle’s frame clean
natural English: The bicycle frame is clean

This is called a nominal sentence. It has:

• هيكل الدراجة = the subject/topic
• نظيف = the predicate/comment

If you wanted was or will be, Arabic would normally use a verb, but for simple present is, it is usually omitted.

It literally means the frame of the bicycle.

This is an iḍāfa construction, often translated as X of Y or Y’s X.

• هيكل = frame / structure
• الدراجة = the bicycle

So:

• هيكل الدراجة = the bicycle’s frame
• or more naturally in English, the bicycle frame

In Arabic, the possessed thing comes first:

• هيكل = frame
• الدراجة = of the bicycle

Because this is how the iḍāfa structure works.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun can be definite, and that makes the whole phrase definite

So:

• هيكل = frame
• الدراجة = the bicycle
• هيكل الدراجة = the bicycle frame

Even though هيكل does not have الـ, the whole phrase is definite because الدراجة is definite.

Compare:

• هيكل دراجة = a bicycle frame
• هيكل الدراجة = the bicycle frame

In an iḍāfa construction, the second noun is in the genitive case.

So the fully vowelled form would be:

هيكلُ الدراجةِ نظيفٌ

Notice:

• هيكلُ = nominative, because it is the subject of the sentence
• الدراجةِ = genitive, because it is the second part of the iḍāfa
• نظيفٌ = nominative, because it is the predicate

In normal Arabic writing, these short vowels are usually not written, but they are still understood grammatically.

Because here نظيف is the predicate of the sentence, not an adjective directly attached to the noun.

There is an important difference:

1. Predicate adjective
   هيكل الدراجة نظيف
   = The bicycle frame is clean

2. Attributive adjective
   هيكل الدراجة النظيف
   = the clean bicycle frame

In Arabic, an adjective that directly describes a noun usually matches it in definiteness, so if the noun phrase is definite, the adjective is also definite.

But in this sentence, نظيف is not part of the noun phrase. It is the statement being made about the noun phrase, so it stays indefinite.

Because نظيف describes هيكل, and هيكل is masculine.

Even though الدراجة is feminine, it is not the main noun being described here. The main noun is:

• هيكل = frame

So the adjective agrees with هيكل, not with الدراجة.

That is why we get:

• هيكل الدراجة نظيف = The bicycle frame is clean

If the main noun were feminine, the adjective would be feminine too.

With full case endings, it is:

هَيْكَلُ الدَّرَّاجَةِ نَظِيفٌ

A rough pronunciation is:

haykalu d-darrājati naẓīfun

Notes:

• الدراجة begins with a sun letter (د), so the l of الـ is not pronounced separately.
  So الدراجة sounds like ad-darrāja / d-darrāja rather than al-darrāja.
• In pause, the final case endings are often not fully pronounced in everyday reading, so someone may simply say:
  هيكل الدراجة نظيف

Yes, but the basic sentence as given is the most straightforward:

هيكل الدراجة نظيف

Arabic can sometimes move parts around for emphasis, but for a learner, this order is the safest and most natural here:

• subject first: هيكل الدراجة
• predicate second: نظيف

If you change the order, it can sound marked, poetic, or context-dependent. So for normal learning and normal usage, keep it as:

هيكل الدراجة نظيف

Yes, depending on context, هيكل can mean frame, structure, or skeleton/framework.

So هيكل الدراجة most naturally means:

• the bicycle frame

But in a different context, it could be understood more generally as:

• the structure of the bicycle

For everyday objects like bicycles, frame is usually the most natural translation.

Because Arabic does not need a separate pronoun here.

English says:

• The bicycle frame is clean

Arabic can simply say:

• هيكل الدراجة نظيف

The relationship between the subject and the predicate is clear without adding هو.

Sometimes Arabic does use a separating pronoun in certain contexts, but in a simple sentence like this, it is not necessary.

You would say:

هيكل الدراجة النظيف

Here, النظيف is an adjective attached directly to the noun phrase, so it matches it in definiteness.

Compare carefully:

• هيكل الدراجة نظيف = The bicycle frame is clean
• هيكل الدراجة النظيف = the clean bicycle frame

This is a very important distinction in Arabic:

• predicate after the subject: usually indefinite
• attributive adjective inside the noun phrase: matches the noun in definiteness, gender, and number