to learn/learning

[wowenglish1]

1. It took me a long time to learn to ride a bike.
If "It" means "to learn to ride a bike",
I think that "1"="2", I wonder why "1"="3".
2. To learn to ride a bike took me a long time.
3. Learning to ride a bike took me a long time.

[euncu]

***neither a teacher nor a native-speaker***

I'd say;
It took a long time to learn to ride a bike for me
or
It took a long time for me to learn to ride a bike

[nuharani]

As far as I know "IT" is impersonal. It means : I found that I took a long time to learn how to ride a bike.for #1

#3 is gerund. Learning to ride a bike took me a long time, I learn every time.

[tedtmc]

not a teacher

'Something' took me a long time
That something is 'learning to ride a bike' (gerund), not 'to learn to ride a bike'. (verb).

[Jaskin]

Hi
Note I'm not a teacher nor a native speaker,

1. It took me a long time to learn to ride a bike.

If "It" means "to learn to ride a bike",

I think that "1"="2", I wonder why "1"="3".
2. To learn to ride a bike took me a long time.
3. Learning to ride a bike took me a long time.

Yes, 'It' has a preparatory function here. If I'm correct it's a preparatory subject. To-infinitive and gerund structures can be used as the subject of a sentence.
It's more common to use gerund forms as a subject especially in an informal style. Using to-infinitives as a subject makes the sentence sounds more formal and distant.
I've heard an opinion that using to-infinitive refers to the event in more general and theoretical way than gerund which refers more to one's own experience.

Unfortunately I'm unable to explain why it so.

I hope it helps,
Cheers

[Searching for language]

***neither a teacher nor a native-speaker***

I'd say;
It took a long time to learn to ride a bike for me While I believe that most people would understand this sentence to mean that you are learning to ride the bike, it is incorrect. You are suggesting that someone else is learning to ride the bike, and they are doing it as a favour to you. If you were incapable of riding a bike because of a physical limitations, your brother might say, "O.k. I don't really want to learn to ride a bike, but as a favour to you, I'll do it.
or
It took a long time for me to learn to ride a bike

I am not a techer.