פעם הייתי נוסע לעבודה באופניים, אבל עכשיו אני נוסע באוטובוס.

Here פעם means in the past / once / back then, not necessarily one single time.

In this sentence, פעם helps set up the contrast with עכשיו (now), so the sense is:

• Back then / I used to...
• But now...

So it is functioning a lot like English used to in meaning.

Because הייתי נוסע expresses a habitual or repeated past action: I used to travel / I would go.

Compare:

• נסעתי לעבודה באופניים = I went/traveled to work by bicycle
  
  • a simple past fact
• הייתי נוסע לעבודה באופניים = I used to go to work by bicycle
  
  • something repeated regularly

So this pattern:

• היה / הייתי / היית... + present participle

is very common for used to / would regularly in the past.

Because Hebrew usually does not use a separate verb like English am/is/are in the present tense for ordinary verbs.

So:

• אני נוסע = I travel / I am traveling / I go
• not literally I am travel

The word נוסע itself is the present-tense form being used here.

In the first clause, הייתי already tells you the subject is I.

• הייתי = I was

So Hebrew does not need to add אני there.

In the second clause, נוסע does not show person. It shows only gender and number:

• נוסע = masculine singular
• but it does not by itself mean I, you, or he

So Hebrew normally includes the pronoun:

• אני נוסע = I go / I am traveling

Because נוסע is a broad verb meaning travel, go, ride, or go by some means of transport, depending on context.

In English, we often switch verbs:

• go to work by bike
• go by bus
• ride a bike

Hebrew often keeps נסע for movement by transport in general. So using נוסע in both clauses is very natural.

The prefix ל־ means to.

So:

• לעבודה = to work

This is very normal Hebrew for going to a destination.

Also, when Hebrew means to work in the everyday sense of going to one's workplace, it often does not use the article the. So לעבודה is more natural here than a more literal אל העבודה.

Here ב־ means something like by / in / on, and it marks the means of transportation.

So:

• באופניים = by bicycle
• באוטובוס = by bus

This is a very common Hebrew pattern:

• באוטו = by car
• ברכבת = by train
• במטוס = by plane

So the idea is: using that vehicle as your method of travel.

Both are possible, but they emphasize slightly different things.

• רוכב על אופניים = ride a bicycle
  
  • focuses more on the physical act of cycling
• נוסע באופניים = go/travel by bicycle
  
  • focuses more on the means of transportation

Since the sentence is about how the person gets to work, נוסע באופניים fits well.

Because אופניים is the normal Hebrew word for a bicycle, even though it has a plural-looking form.

Historically and grammatically, it behaves like a plural/dual form, but in everyday Hebrew it simply means bicycle.

That is why learners often notice forms like:

• אופניים חדשים = a new bicycle (literally with plural agreement)

So yes, it looks plural, but it is the standard everyday word for one bicycle.

In this sentence, it most naturally means now / these days / currently, not necessarily at this exact moment.

Because the sentence contrasts:

• פעם = in the past
• עכשיו = now

the meaning is:

• I used to go to work by bike, but nowadays I go by bus.

So עכשיו can be broader than just right this second.

Because נוסע is the masculine singular form.

If the speaker were female, it would be:

• פעם הייתי נוסעת לעבודה באופניים, אבל עכשיו אני נוסעת באוטובוס.

Notice:

• הייתי stays the same
• נוסע changes to נוסעת

So the gender is shown by the participle נוסע / נוסעת.

Not necessarily. In unpointed Hebrew, באוטובוס can be a little ambiguous in spelling.

It can represent:

• בְאוטובוס = by/in a bus
• or בָאוטובוס = by/in the bus

Without vowel marks, both are written the same way: באוטובוס.

In this sentence, the meaning is clearly the general one: by bus.

So the important thing for a learner is:

• ב־ is attached directly to the noun
• the spelling may look a little tricky when the word starts with א