how did sonic get so fast in the first place

[classic sonic]

I think it is because of a accident in dr. robotnik's place

[Polkadi~☆]

Because Sonic is naturally fast. There's no reason why, he doesn't need a reason. He just is fast.

[Rabid-Coot]

Blast processing.

[MetalSkulkBane]

Officially?
No answer. He just is.

Semi-officially?
There was story in Sonic Early Canon (like Fleetway Comic) that Sonic was "normal" brown talking hedgehog, friend with nice scientist Kintobor and then few accidents happened and here we are. Obviously that is no longer canon, arguably never was.

My head canon?
In Sonic 1 he was fast athlete-fast, not magic-fast. Since so many Sonic characters can run fast, it's not impossible. Spin Attack isn't much different from martial arts, many people can learn it. But hedgehogs are natural at it.
Add hundreds of rings, seven chaos emeralds and few visits to Special Stage and Sonic can now boost and ignore psychics. His speed got naturally enhanced by all his adventures and exposure to chaos energy. Thus being a hero in a first place, made him a hero he is today.

[LeviTheGreat]

3 hours ago, MetalSkulkBane said:

Officially?
No answer. He just is.

Semi-officially?
There was story in Sonic Early Canon (like Fleetway Comic) that Sonic was "normal" brown talking hedgehog, friend with nice scientist Kintobor and then few accidents happened and here we are. Obviously that is no longer canon, arguably never was.

My head canon?
In Sonic 1 he was fast athlete-fast, not magic-fast. Since so many Sonic characters can run fast, it's not impossible. Spin Attack isn't much different from martial arts, many people can learn it. But hedgehogs are natural at it.
Add hundreds of rings, seven chaos emeralds and few visits to Special Stage and Sonic can now boost and ignore psychics. His speed got naturally enhanced by all his adventures and exposure to chaos energy. Thus being a hero in a first place, made him a hero he is today.

Just building on what was very well said by @MetalSkulkBane.There have been many stories of how Sonic got his speed.

The early ones started on Sat-am with Sonic and his shoes.

Another was already adressed.(Fleetway Comic)

If you know Sonic Underground maybe Sonic had father who had speed but Robotnik/Eggman is hiding that secret from him (Theory).

Sonic X seems the most logical to me because it connects with the games and shows how the whole cast of characters are affected if Sonic isnt around>

[Blue Blood]

16 hours ago, Polkadi~☆ said:

Because Sonic is naturally fast. There's no reason why, he doesn't need a reason. He just is fast.

Quote for truth. 

Sonic's a simple, easy to digest and understand character. Not everything needs lore behind it. He doesn't have a backstory or a history explaining why he's so fast because it's not necessary for him to gave a story any deeper than "he's good and he's cool", and it detracts from the simple premise. The movie does a surprisingly good job at not explaining Sonic's speed or heroism. He just is. That's the way it always has been officially and I hope that that never changes.

Of course there have been various explanations offered in different canon/non-canon sources. Regular-hedgehog turned blue and fast by science experiments, it's all about his shoes and whathaveyou, but none of them really hope up under am ounce of scrutiny and all create more questions than they answer. 

[Plumbers_Helper]

On 12/21/2020 at 7:46 AM, LeviTheGreat said:

The early ones started on Sat-am with Sonic and his shoes.

Another was already adressed.(Fleetway Comic)

Those were just the origins of Sonic's shoes, and in Sonic the Comic's case also why Sonic is blue, not where he got his Super Speed from. Sonic was already super fast before he got his shoes from Dr. Kintobor or his Uncle Chuck.

The only piece of media that I'm aware of to explain how Sonic got his speed and abilities in detail comes from the now non-canon Sega of America Bible/Stay Sonic Novel/Sega of America website. Basically, Sonic learned all his abilities from the animal friends you rescue in Sonic 1. All three sources say Sonic learned to run fast from the rabbit Pocky: "Johnny Lightfoot, a rabbit and Mobius's undisputed sprint champion at the time, coached Sonic, and soon he was able to outstrip every other creature in the forest." - Stay Sonic Pg 18. The pig Picky/Porker Lewis is only mentioned in in the bible and Flicky isn't mentioned in the Stay Sonic novel for some reason. In an early version of the bible a note in pen says "BORN FAST - NOT SUPERMAN W/O KRYPTONITE".

Although Fleetway's Sonic the Comic used the Kintober origin story found in this early canon, it never used the origin of Sonic learning his speed and abilities from his friends.

[classic sonic]

On 12/20/2020 at 5:27 PM, classic sonic said:

I think it is because of a accident in dr. robotnik's place

thanks for answering and also here's the Tails Doll for you