What's wrong with my bike and how do I fix it?

[Carnotaurus]

What's wrong with my bike and how do I fix it?

I posted these videos earlier:

http://www.youtube.com/watch?v=rVpPuqiwQTo

http://www.youtube.com/watch?v=FqdABuPRH68

[Painkiller]

your video was lacking at best, sorry. try describing the problem you are having. and maybe some pics of your bike in the upright position. one directly from behind and from the side of the rear derailluer area.
I generally do not work on bikes upside down. as it stands it could be anything from bad bearings to derailluer out of alignment to bad freehub.. need more info

[FredS]

I thinking the chain, how old is the chain and does it have any stiff links or is it rusty?

[torquecyclerepairs]

I would say chain and possibly freewheel/freehub body. Sounds like it's time to pop your bike into a reputable repair shop.

[jaydenthecreator]

Could someone help me out? I recently purchased a new single speed bike sprocket. I put it on my bike and I had to make the chain smaller. Anyways I got everything put together and its as if the bike doesn't have enough tension when you pedal. like when you pedal it feels like the chain isn't even on. the cranks spin almost to freely.