Какой бы чай ты ни выбрал, я всё равно возьму кофе.

It is a set pattern meaning no matter which or whichever.

So Какой бы чай ты ни выбрал means something like:

• no matter which tea you choose
• whichever tea you choose

This construction is very common in Russian:

• кто бы ни пришёл = no matter who comes
• что бы ты ни сказал = no matter what you say
• где бы он ни жил = no matter where he lives

It expresses that the result in the main clause does not change.

Because together they form this special free-choice / concessive construction.

Very roughly:

• бы helps create a hypothetical or non-factual idea
• ни reinforces the meaning it does not matter which / who / what

So какой бы ... ни is a fixed grammatical pattern. If you remove one of them, the sentence either becomes ungrammatical or changes meaning.

For example:

• Какой бы чай ты выбрал sounds incomplete by itself in this meaning.
• Какой чай ты ни выбрал is not the normal standard way to express this idea.

So it is best to learn какой бы ... ни as one chunk.

Because ни is the correct particle in this construction.

A native English speaker often expects ordinary negation, but this is not really a negative sentence. It is a concessive pattern: no matter which tea you choose.

Compare:

• не usually makes standard negation
• ни often appears in emphatic or dependent constructions like this one

So here ни does not mean simple not. It is part of the structure:

• кто бы ни
• что бы ни
• как бы ни
• где бы ни
• какой бы ... ни

Because in Russian, the form used with бы is built from the past-tense form of the verb, even when the meaning is hypothetical, non-past, or future-like.

So выбрал here is not really you chose in a past-time sense. It is part of a structure meaning:

• you might choose
• you were to choose
• you choose, in a hypothetical sense

This is similar to how Russian forms the conditional/subjunctive:

• я сделал бы = I would do
• ты выбрал бы = you would choose

In your sentence, бы is attached to какой, but it still affects the whole clause.

Because this specific construction normally uses the бы + past-form pattern, not the regular future tense.

So:

• Какой бы чай ты ни выбрал = no matter which tea you choose
• not Какой бы чай ты ни выберешь

The form выберешь is a normal future tense, but after какой бы ... ни, Russian uses the past-form-based subjunctive pattern.

This is one of those places where Russian grammar does not line up neatly with English grammar.

Because the verb agrees with ты, and here the speaker is apparently talking to a male person.

With ты, past-tense forms show gender:

• ты выбрал = you chose / would choose, addressing a man
• ты выбрала = addressing a woman

So if the speaker were talking to a woman, the sentence would be:

Какой бы чай ты ни выбрала, я всё равно возьму кофе.

Because чай is the object of выбрал, so it is in the accusative case. For masculine inanimate nouns, the accusative often looks exactly like the nominative.

So:

• nominative: какой чай
• accusative: какой чай

They look the same here.

If the noun were feminine, you would see the case more clearly:

• Какую книгу ты выбрал? = Which book did you choose?
• Какую бы книгу ты ни выбрал... = No matter which book you choose...

So какой agrees with чай in gender, number, and case.

Всё равно means something like:

• anyway
• all the same
• regardless
• it makes no difference

So я всё равно возьму кофе means:

• I’ll take coffee anyway
• I’ll still have coffee
• I’m going to choose coffee regardless

It emphasizes that the other person's choice does not affect the speaker’s decision.

Возьму is the 1st person singular future of the perfective verb взять.

In this context it means:

• I will take
• I’ll have
• I’ll choose

Russian often uses взять in situations like ordering or choosing food and drinks:

• Я возьму чай. = I’ll take tea.
• Я возьму кофе. = I’ll take coffee.

The perfective form fits well because it refers to a single completed choice.

Yes, often it can.

Russian frequently omits personal pronouns when the verb form already makes the subject clear. So you may see:

Какой бы чай ни выбрал, я всё равно возьму кофе.

But in your sentence, ты is included for clarity or emphasis. It can sound more direct:

• ты = explicitly you

Including the pronoun is completely natural.

Russian word order is flexible, but not every order sounds equally natural.

The standard, natural order here is:

Какой бы чай ты ни выбрал...

You may also encounter variants, but Какой бы ты ни выбрал чай is less neutral and can sound awkward in ordinary speech. Russian usually keeps какой close to the noun it modifies:

• какой чай

So for learners, the safest pattern is:

• Какой бы + noun + subject + ни + past-form verb

Example:

• Какую бы книгу ты ни купил...
• Какой бы фильм они ни посмотрели...

Because the first part is a subordinate clause, and the second part is the main clause.

• Какой бы чай ты ни выбрал = subordinate clause
• я всё равно возьму кофе = main clause

Russian separates them with a comma, just as English often separates no matter which tea you choose from the main statement.

So the comma is required.

Yes, but the nuance may change.

For example, you could say something simpler like:

• Выбирай любой чай, я всё равно возьму кофе.
  = Choose any tea; I’ll take coffee anyway.

Or:

• Что бы ты ни выбрал из чая, я всё равно возьму кофе.
  = Whatever tea you choose, I’ll take coffee anyway.

But Какой бы чай ты ни выбрал... is a very natural and elegant way to express whichever tea you choose. It is especially useful to learn because the same pattern works with many question words:

• кто бы ни
• что бы ни
• где бы ни
• как бы ни
• какой бы ... ни