If you have a single speed there will not be any screws. How loose is the chain? You can tighten the chain by loosening the rear wheel nuts, pulling the wheel back and retightening. You want a little slack in the chain, not TIGHT. The bottom bracket could be loose as well(The crank will wiggle) You might want to go to a bike shop to get that adjusted.
__________________
Are you a registered member? Why not? click here to register. Its free, and only takes 27 seconds!
Help out the forums, abide by our community guidelines.
I am in the woods and I have gone crazy.