Problems with 'The Collector' mission in Endless Summer

[Dude Rain]

How exactly does one go about doing this?

Every time I try to nab the bike from the person riding it, I'm almost immediately accosted by a cop and wrestled to the ground.

One time I managed to get one bike, but was arrested on the second bike. I have no idea how I'm supposed to get 3....

Am I missing something?
Thanks in advance.

EDIT: And of course I get it on the second try after posting here.

I didn't realize you could "carjack" a bicycle by just running up to the cyclist and pressing Y. I was trying to shoot them off with the slingshot. Doing that causes cops to spawn all around you.

[KrAzY aLbAnIaN]

as soon as u press the y button to rob the bike he will first kick the guy off the bike, after this is done do not try to get to teh bike right away as the cops will bust you, rather jus run around making them chase u then as u have them at a certain distance behind u, u can pick up the bike as u run

[BluntedSaboteur]

I am also struggling mightily with this mission, but I also did not know that you could bike-jack someone using the y button. Thanks for the tip as I am going to give it a go...

EDIT: First try using this technique...I fully agree that using the sling-shot/rocket gun is not the way to approach this mission