syataizyuuryou ga karui kara, hakobi yasui wake da.

車体重量 is a compound noun:

• 車体 = the body of a vehicle or machine
• 重量 = weight

So 車体重量 means something like the weight of the main body or vehicle body weight. It sounds fairly technical, like wording you might see in product specs, manuals, or advertisements.

They are read:

• 車体重量 → しゃたいじゅうりょう
• 運びやすい → はこびやすい

Also, the full sentence is read:

しゃたいじゅうりょう が かるい から、はこびやすい わけ だ。

Here, が marks 車体重量 as the thing that has the property 軽い.

So the structure is basically:

• 車体重量が軽い = the body weight is light

If you used は instead, it would sound more like setting up 車体重量 as the topic, often with a contrastive or explanatory feel:

• 車体重量は軽いから…

That is also possible, but が is very natural when simply describing what is light.

Yes, and that is completely normal in Japanese, just as light weight is normal in English.

Japanese often uses:

• 重い = heavy
• 軽い = light

with nouns related to weight, including 重量. So 重量が軽い is not strange. It simply means the weight is low/light.

から means because or since.

In this sentence:

• 車体重量が軽いから = because the body weight is light

A key point is that から can attach directly to the plain form of an adjective:

• 軽い + から

So there is no extra word needed between 軽い and から.

Because 〜やすい attaches to the verb stem, not the dictionary form.

The verb is:

• 運ぶ = to carry / transport

Its stem is:

• 運び

Then you add やすい:

• 運びやすい = easy to carry / easy to transport

This pattern is very common:

• 読みやすい = easy to read
• 使いやすい = easy to use
• 分かりやすい = easy to understand

They are related, but not the same.

• 運びやすい = easy to carry
• 運べる = can carry / be able to carry

So 運びやすい talks about ease or convenience.
運べる talks about possibility or ability.

For example:

• 運べる: It is possible to carry it.
• 運びやすい: It is not difficult; it is convenient to carry.

In this sentence, the point is not just that carrying is possible, but that the light weight makes it easy.

わけだ gives a sense of that explains it, that’s why, it follows that, or sometimes no wonder.

Without it, the sentence would simply say:

• 車体重量が軽いから、運びやすい。
• Because the body weight is light, it is easy to carry.

With わけだ, the speaker sounds like they are drawing a logical conclusion from the reason:

• Because the body weight is light, that’s why it’s easy to carry.

So わけだ adds an explanatory, concluding nuance.

Here, だ is the plain-form copula attached to わけ:

• わけだ

This is a common expression. It gives the sentence a plain, direct style.

Compare:

• わけだ = plain
• わけです = polite

So the sentence could also be made polite as:

• 車体重量が軽いから、運びやすいわけです。

Yes. You can say:

車体重量が軽いから、運びやすい。

That is grammatically fine and very natural.

Adding わけだ makes it sound more like the speaker is explaining the result or pointing out a conclusion. In other words:

• without わけだ: a simple statement
• with わけだ: an explanatory conclusion

Japanese often leaves out information that is obvious or unimportant from context.

In this sentence, the focus is on the item’s property:

• it has a light body weight
• therefore it is easy to carry

Who carries it does not need to be stated. English often wants a clearer subject, but Japanese frequently omits it when the meaning is already understood.

The comma after から is not strictly required, but it is very natural.

It helps separate:

• the reason: 車体重量が軽いから
• the result/conclusion: 運びやすいわけだ

So it improves readability, especially in explanatory writing.

It sounds plain in grammar but somewhat technical in vocabulary.

Why:

• 車体重量 is a technical/specification-like term
• わけだ is plain style, not highly polite
• the overall sentence would fit well in product explanations, catalogs, reviews, or manuals

So it is not slangy casual speech, but it is also not especially polite unless you change the ending to わけです.