Drive to the marked location after receiving this job. Get off your Bike and examine the corpse by the pond. As soon as you finished examining the body, your target will ride past you. Quickly return to your bike and give chase.
This is your Tutorial for Bike Combat. Tap L1 to highlight the target then press R1 to fire your sidearm. To make your shot more accurate, you have to wait for the reticule to become smaller. This is affected by your relative distance to the target.
You can also deliberately ram your Bike at the target to conserve ammo. If you ran out of ammo, you have no choice but to rely on this crude method. Take note that your bike will also take damage while doing this.
If your Bike took a lot of more damage first and when you’re having a hard time catching up, just keep following him. As long as his bike is critically damaged, it will blow up automatically after a while, leading to his capture. Mission complete.