Learn Hardcore Polish: Teraz jadę tramwajem do centrum, ale na co dzień jeżdżę tam rowerem. - Now I am going by tram to the center, but on a daily basis I ride there by bike.

Teraz jadę tramwajem do centrum
= Right now I’m going by tram to the center (one concrete trip happening now).
ale na co dzień jeżdżę tam rowerem.
= but on a daily basis I go there by bike (how I usually do it, as a habit).

So jechać = one direction / one occasion;
jeździć = “back and forth”, “generally”, “habitually”.

Why is it jadę and not something like jestem jadący for “I’m going”?

Polish does not have a separate continuous tense like English “I am going” vs “I go”.

Present tense forms usually cover both:

jadę can mean:
- I go / I am going (now, currently, in progress)

To show that it’s happening now, you add an adverb like teraz (now), w tej chwili (at this moment), etc. The grammar form is just the plain present tense.

Why is it jadę and not idę?

Polish uses different verbs for going on foot vs by vehicle:

iść (idę) – to go on foot, one specific trip
chodzić (chodzę) – to go on foot, habitually / generally
jechać (jadę) – to go by some vehicle (car, tram, train, bike, etc.), one specific trip
jeździć (jeżdżę) – to go by vehicle, habitually / generally

Because this sentence talks about going by tram and by bike, it must use jechać / jeździć, not iść / chodzić.

So:

Teraz jadę tramwajem – I’m going by tram (now)
Na co dzień jeżdżę tam rowerem – I usually go there by bike

Why are tramwajem and rowerem in that -em form? What case is that?

Tramwajem and rowerem are in the instrumental case.

In Polish, the instrumental is used to express “by / with / using” something as a means:

jadę tramwajem – I go by tram
jadę rowerem – I go by bike
piszę długopisem – I write with a pen

Masculine (and neuter) singular instrumental typically ends in -em:

tramwaj → tramwajem
rower → rowerem

You don’t add a preposition like by; the case ending -em itself shows the “by/with” meaning.

Why is there no preposition with tramwajem and rowerem, like “z tramwajem” or “na rowerze”?

With means of transport, Polish usually uses the bare instrumental case (no preposition) to mean “by …”:

jadę tramwajem – I’m going by tram
jeżdżę rowerem – I go by bike
lecę samolotem – I fly by plane

If you added a preposition, it would mean something else:

z tramwajem – with a tram (accompanying a tram, sounds strange)
na rowerze – on a bike (physically on top of a bike; can be used in some contexts but not the standard “by bike” after jechać / jeździć)

So the natural, standard way to say “by tram / by bike” is instrumental without a preposition.

What does na co dzień mean exactly, and how is it different from codziennie?

Both relate to things done regularly:

na co dzień = in everyday life, as a rule, in general, “normally”
codziennie = every day (literally, “daily”)

In the sentence:

ale na co dzień jeżdżę tam rowerem
= but in everyday life / normally I go there by bike.

You could also say:

ale codziennie jeżdżę tam rowerem
= but every day I go there by bike (emphasising daily frequency).

Na co dzień is more about your usual way of doing something, not necessarily literally every single day.

Why is it do centrum? What case is centrum, and why doesn’t it change?

The preposition do (“to, towards”) always takes the genitive case.

do
- genitive → do centrum

But centrum is a neuter noun that looks the same in nominative and genitive singular:

nominative: (to) centrum
genitive: (do) centrum

So the form doesn’t visibly change, but grammatically it is genitive because of do.

More examples:

do szkoły (from szkoła → szkoły, visible genitive)
do pracy (praca → pracy)

Why is tam used here? Isn’t do centrum already “to the center”?

Tam means “there” and is often used to refer back to a place that was just mentioned or is known from context.

In this sentence:

Teraz jadę tramwajem do centrum, ale na co dzień jeżdżę tam rowerem.

tam refers back to centrum: “I usually go there by bike.”

Is it strictly necessary? No, grammatically you could say:

…ale na co dzień jeżdżę rowerem do centrum.

But tam is very natural in spoken Polish and makes the contrast clearer:

now I’m going there (to that place) by tram,
usually I go there by bike.

Could I change the word order, like Teraz do centrum jadę tramwajem or Teraz jadę do centrum tramwajem?

Yes. Polish word order is quite flexible. All of these are correct:

Teraz jadę tramwajem do centrum. (neutral)
Teraz jadę do centrum tramwajem.
Teraz do centrum jadę tramwajem.
Teraz tramwajem jadę do centrum.

The differences are mostly about emphasis:

Putting something earlier tends to give it more focus.
Teraz tramwajem jadę do centrum could suggest a contrast like “by tram (not by car / not on foot).”

But for learners, the original order Teraz jadę tramwajem do centrum is a good, very natural default.

Can I replace na co dzień with something like zwykle or normalnie?

Yes. Several adverbs can express “usually / normally”:

na co dzień – in everyday life / normally
zwykle – usually
normalnie – normally
przeważnie – mostly, for the most part

So you could also say:

Teraz jadę tramwajem do centrum, ale zwykle jeżdżę tam rowerem.
…ale normalnie jeżdżę tam rowerem.

The meaning is very similar; na co dzień just sounds a bit more like “as my everyday habit.”

Do jadę and jeżdżę change depending on whether the speaker is male or female?

In the present tense, verb forms do not change for gender, only for person and number.

So:

Ja jadę / ja jeżdżę
- is used by a man or a woman, same form.

Gender affects:

past tense (e.g. jechałem vs jechałam)
some adjectives and participles

But in the present tense sentence:

Teraz jadę tramwajem do centrum, ale na co dzień jeżdżę tam rowerem.

the forms are identical for male and female speakers.

What are the full present tense conjugations of jechać and jeździć?

Present tense of jechać (one specific trip):

ja jadę – I’m going (now, one trip)
ty jedziesz
on / ona / ono jedzie
my jedziemy
wy jedziecie
oni / one jadą

Present tense of jeździć (habitual / general):

ja jeżdżę – I (usually) go / ride
ty jeździsz
on / ona / ono jeździ
my jeździmy
wy jeździcie
oni / one jeżdżą

In the sentence:

jadę ← jechać (one trip, now)
jeżdżę ← jeździć (habitual).