אילו השלדה הייתה קלה יותר, הייתי קונה את האופניים.

Here אילו means if.

That is because it introduces a whole conditional clause: אילו השלדה הייתה קלה יותר... = if the frame were lighter...

Hebrew אילו can also mean which in a more formal style, but in that use it normally comes directly before a noun phrase, for example:

• אילו אופניים אתה רוצה? = Which bicycle(s) do you want?

So in this sentence, the structure makes it clear that אילו is the conditional word if, not the question word which.

Also, אילו sounds a bit more formal or literary than אם.

Because Hebrew often uses a past form in unreal / hypothetical conditions.

So:

• אילו השלדה הייתה קלה יותר
  literally looks like if the frame was lighter
• but functionally it means if the frame were lighter

This is very similar to English, which also uses a past-looking form in counterfactual sentences:

• If it were lighter, I would buy it.

So הייתה does not mean the frame actually was lighter in the past. It is part of the hypothetical pattern.

Because השלדה is a feminine singular noun.

In Hebrew, both the verb and the adjective often agree with the noun in gender and number:

• השלדה = feminine singular
• הייתה = was / were (feminine singular)
• קלה = light (feminine singular)

If the noun were masculine singular, you would expect masculine forms instead, for example:

• הכיסא היה קל יותר = the chair was/were lighter

So the feminine forms here are simply agreement with השלדה.

Hebrew usually forms the comparative with יותר = more.

So:

• קלה = light (feminine)
• קלה יותר = more light = lighter

Hebrew often does this instead of using a special one-word comparative like English lighter, bigger, better, and so on.

You may also hear יותר קלה in everyday speech. Both are possible, and קלה יותר is perfectly natural.

Hebrew does not have a separate single-word conditional form like English would buy.

A very common way to express this idea is:

• a form of להיות in the past
• the present-tense form of the main verb

So:

• הייתי קונה = I would buy

Literally, it looks like I was buying, but in the right context—especially after if—it means I would buy.

Compare:

• אני אקנה = I will buy
• הייתי קונה = I would buy

So the sentence is using the normal Hebrew pattern for a hypothetical result.

Yes. By itself, הייתי קונה can also mean something like I used to buy or I would buy habitually, depending on context.

For example:

• כשהייתי צעיר, הייתי קונה ספרים כל שבוע
  = When I was young, I used to buy books every week

But in your sentence, the first clause with אילו makes the meaning clearly conditional:

• If the frame were lighter, I would buy the bicycle.

So here there is no real ambiguity.

In unpointed Hebrew spelling, קונה can represent either:

• masculine singular
• feminine singular

So the written form stays the same.

In speech, the pronunciation differs, but in normal everyday writing you usually do not see that difference. That means הייתי קונה could be said by either a man or a woman.

So this sentence does not clearly show the speaker's gender in ordinary spelling.

Because אופניים is one of those Hebrew nouns that is normally used in a plural/dual-looking form even when it refers to a single item.

This is a bit like English words such as scissors or pants, which look plural even when referring to one object.

So:

• אופניים = bicycle / bike
• האופניים = the bicycle / the bike

Grammatically, it usually behaves as a plural noun. For example, speakers often use plural agreement with it.

If you want to count bicycles more explicitly, Hebrew often uses:

• זוג אופניים = a bicycle / a pair of bicycles
• שני זוגות אופניים = two bicycles / two pairs of bicycles

Because the sentence is talking about specific things:

• השלדה = the frame
• האופניים = the bicycle / the bike

This suggests that the speaker and listener already know which bicycle is being discussed. In other words, it is not just any frame and any bicycle in general, but a particular one.

If you wanted a more general or indefinite idea, the sentence would probably be phrased differently.

No. Hebrew does not need an extra word like then in an if-sentence of this kind.

So this is already complete:

• אילו השלדה הייתה קלה יותר, הייתי קונה את האופניים.

You can add אז for emphasis:

• אילו השלדה הייתה קלה יותר, אז הייתי קונה את האופניים.

But in many cases it is unnecessary, and the version without אז sounds more natural.

Yes, it is grammatical and natural, but it sounds a little formal because of אילו.

In everyday conversation, many speakers would more likely say:

• אם השלדה הייתה קלה יותר, הייתי קונה את האופניים.

You might also hear:

• אם השלדה הייתה יותר קלה, הייתי קונה את האופניים.

So the original sentence is good Hebrew, but it has a slightly more written or literary feel than the most casual spoken version.