I'm going to play music with a speaker on my bicycle.
Why do you want to do that?
I like the idea of making people happy in the streets.
While you might think it will make people happy, many people find others playing loud music in the streets to be disturbing and unpleasant. You should check with your neighbors first before playing music loudly outside.
I think it's helping my cause.
Not everyone wants to listen to or likes the same music as you do. Play it at a reasonable level and don't push your music on other people.