How do I know When to change Brake pads?
 

When can I notice that I have to change the brake pads?

Look at the pads...seriously though take a look at how much friction material(pad) is left...if it is thin then replace em...

I think if you look in your owner's manual or in the mechanic guide that is available for the f4i; try to google it, or look around on this forum. It says that there are wear grooves on each brake pad, and if they are wore pass this groove (groove disappears) then its time to replace them. I'm pretty sure thats its right in the middle of the brake pad and runs horizontal. You should be able to see it without taking anything off the bike.

It's easier to see if you take the calipers off (takes one socket) and then you can check the wear groove (big groove in the middle). If there is no groove replace the pads other wise put the calipers back on and ride (don't forget to pump the brakes after you put the calipers back on).