hi im new to this forum and i think its great so far, so im asking you professionals, my fixie currently has been making the clicking noise where the cog is whenever i pedal and i also notice that when i pedal my chain gets tighten looking then loose looking then tighten looking, wave like looking ..., if you guys know what i mean. thx ahead of time guys.

So it gets real tight then gets loose in spots.

Remove wheel from frame and try to spin the hub axle, if you can't, you need new bearings, that could be what is causing the clicking, also check the spokes for a loose spoke.

For the tight and loose spot, it's likely something to do with the chainring up front. I've had luck getting rid of this by simply loosening up the chainring bolts without removing them while the chain is still under tension, doing this should allow the chainring to set better, then retighten the chainring bolts to an even tension. It won't make it go completely away, since almost all chainrings will not be absolutely round, but it will be much better than it was.

thx, my chain moves like this while in motion in this vid, not my vid but this is what happens to my chain when its spinning, but more obvious.

https://www.youtube.com/watch?v=Wz0FF...eature=related

low end chainring that is not very round
low end cog that is chipped/bent
off-center chainline and/or chain too wide
dirty drive train that needs cleaning and lube

mmm ill check for the chainring thing, so all i do is untighten the chainring bolt and adjust? what do i adjust afterwards..

Raise the bike off the ground and turn the crank slowly. Stop at the tightest position and loosen (do not remove) the chainring bolts. The ring will "adjust" on its own. Retighten. Repeat.