Why isn't there a lot of black people in rock bands?

There are black people in rock and metal, just heavily lacking in numbers, but maybe not quite as bad as we thought.
Off the top of my head: singer of Sevendust, singer of killswitch engaged, like half of Suicidal Tendencies are black, the death metal band Suffocation has a couple black members, lead guitarist of Blasphemy is black, singer of Hirax is black, all of In Living Color are black, Jada Smith (Will Smith's wife) got into hard rock and made a hard rock band sometime in the 2000's. And a little fun fact: Rapper Ice-T is a big fan of metal, rock, and some punk and started a band called Bodycount, he even did guest vocals for a death metal band on one of their albums. And I'm not 100% sure, but I think he's done work with Suicidal Tendencies before as well.

Same reason there aren't many white people in rap and hip hop.

There are a lot more than you think. There are actually more black people in metal than in rock, from what I suspect. The only thing is they don't seem to come out to the concerts as much as everyone else does. I have a few black friends that are diehard though and frequent concerts more than my white ass does. I went to a predominately black and latino high school and they would low key listen to at least 1 rock or metal band. And whenever they heard my music, they liked it. I did a project in music class of a female-fronted metal band and everyone loved this one song I chose, a bunch of my classmates downloaded it. And I'm one of 5 white people in that school. Most of them are too concerned about what other black people will think about them. I think this is because it is sometimes called "white people music" when in fact it is music for everyone.

Some very racist stereotypes here. Little Richard, Bo Diddley and Chuck Berry are black, and they invented rock

Stereotyping, originally Rock-Bands were very mixed, but with the stereotyping/image-culture that developed in the late-70s, and 80s, we segregated rock to a 'white' hobby.

Do you know there are more Asian rock bands and singers than anywhere else in the world ?

Black people are soulful.

Rap is their thang

Black people are soulful.

Idk. Same thing is why aren't they're many white rappers in mainstream music.(other than eminem) everyone is pretty much raised into stereotypes :/

I don't know - I guess black people tend to go into the hipster, indie, rap, break areas while 'white' people go into rock, scene,emo, gothic, and indie/hipster areas.
But everyone can be what they want so I suspect that it's the way kids are raised and their environment (not saying anything against any races).

Mainly they are not into rock music. Maybe some of them like Rage against the machine.