Chúng tôi đạp xe cùng nhau.

Because chúng tôi means we, but it does not include the person being spoken to.

• chúng tôi = we (excluding you)
• chúng ta = we (including you)

So if the speaker is talking about a group that does not include the listener, chúng tôi is the right choice.

For example:

• Chúng tôi đạp xe cùng nhau. = We rode bikes together. (not including you)
• Chúng ta đạp xe cùng nhau. = We rode bikes together. (including you)

This is a very common distinction in Vietnamese and often surprises English speakers, since English uses just we for both.

đạp xe is a common Vietnamese verb phrase meaning to ride a bicycle or to cycle.

Literally:

• đạp = to pedal
• xe = vehicle

But together, đạp xe is understood as riding a bike/cycling.

So learners should treat đạp xe as a set phrase, not translate it word by word every time.

This is a very common point of confusion.

• xe đạp = bicycle
  
  • literally, a pedal vehicle
• đạp xe = to ride a bicycle / to cycle

The same two elements appear, but the order changes because the grammar changes:

• xe đạp is a noun
• đạp xe is a verb phrase

So:

• Tôi có một chiếc xe đạp. = I have a bicycle.
• Tôi đạp xe mỗi sáng. = I cycle every morning.

cùng nhau means together.

It emphasizes that the action was done jointly.

• Chúng tôi đạp xe. = We rode bikes.
• Chúng tôi đạp xe cùng nhau. = We rode bikes together.

In many situations, you could omit cùng nhau if the idea of doing it together is already clear from context. But adding it makes the meaning more explicit and natural when you want to stress the shared activity.

Usually, in this sentence, cùng nhau is the more natural expression for together.

• cùng nhau = together, with each other

Using cùng by itself often means with someone or together with, and it often needs another word after it:

• Tôi đi cùng bạn. = I go with you.

So for this exact meaning, Chúng tôi đạp xe cùng nhau is better than just Chúng tôi đạp xe cùng.

The sentence follows a very common Vietnamese pattern:

subject + verb phrase + adverb/complement

So here:

• Chúng tôi = subject
• đạp xe = verb phrase
• cùng nhau = adverbial phrase meaning together

That gives:

Chúng tôi | đạp xe | cùng nhau.

This is similar to English word order in a sentence like We rode bikes together.

By itself, it does not clearly mark tense.

Vietnamese verbs do not change form the way English verbs do. So đạp xe can mean different things depending on context:

• We ride bikes together
• We rode bikes together
• We have been riding bikes together

If you want to make the time clearer, Vietnamese often adds markers like:

• đã for past
  
  • Chúng tôi đã đạp xe cùng nhau. = We rode bikes together.
• đang for ongoing action
  
  • Chúng tôi đang đạp xe cùng nhau. = We are riding bikes together.
• sẽ for future
  
  • Chúng tôi sẽ đạp xe cùng nhau. = We will ride bikes together.

So the base sentence is neutral unless context tells you the time.

Yes, chúng tôi is standard and neutral, and it can sound a bit more formal or careful than some everyday alternatives.

Depending on region and situation, speakers might also say:

• tụi tôi
• bọn tôi
• bọn mình (this one can be more nuanced depending on context)

For learners, chúng tôi is a very safe choice in standard Vietnamese.

Yes. That is also natural.

Compare:

• đạp xe = to cycle / ride a bike
• đi xe đạp = to go by bicycle / ride a bicycle

Both can work here. In many everyday situations, the difference is small.

• Chúng tôi đạp xe cùng nhau.
• Chúng tôi đi xe đạp cùng nhau.

Both can mean We rode bikes together or We bike together, depending on context.

A learner-friendly breakdown is:

• Chúng — rising tone
• tôi — level tone
• đạp — heavy, low stopped tone
• xe — level tone
• cùng — falling tone
• nhau — level tone

A rough approximation for English speakers is:

• chúng tôi ≈ choong toy
• đạp xe ≈ dap seh
• cùng nhau ≈ koong nyow

But these are only rough guides. The tones and Vietnamese vowel quality matter a lot, so it is best to listen to native audio and imitate the rhythm of the whole phrase.

Not literally in the same way English does.

Vietnamese usually does not mark singular vs. plural on nouns unless it needs to. In this sentence, đạp xe is a verb phrase meaning ride a bike / cycle, so there is no separate plural noun like English bikes.

English often chooses bikes in translation because it sounds natural, but Vietnamese leaves the number unspecified unless context makes it important.