Rear cog needs to come off!
 

I have limited tools and am looking to replace my rear cog... i need some help, can anyone give some advice. I tried with the chain, but i couldn't get it to come off. The lock ring is off and just waiting for some help. Thanks!

you need something with leverage. try fashioning some extra chain lengths to like a steel handle of some sort. Obviously, you can buy a chain whip buy I have seen some homemade ones that do the trick

is there locktight on the cog? if so, you could heat up it up to loosen the locktight and it would become easier to get the cog off

By "trying with the chain" do you mean you just pulled on it, like with the pedals, or did you try to rotafix it off? Because that's what I'd suggest if you don't have a chainwhip.

http://204.73.203.34/fisso/eng/schpignone.htm

Just wrap the chain around the bottom of the cog and rotate the wheel clockwise to get the cog off.

I bent my chain whip a few weeks ago trying get a cog off with two good years of riding on it. It came right off using the rotafix method.

Rotofix for installation and removal.

go to the bike shop.