Check that the back wheel is fitted correctly. is it wobbly becasue it is buckled, or because it is not tight onto the bike.
if the wheel is buckled then it should go to a store to be straitened depends on how bad it is .
if not put bike upside down and undo the back wheel nuts a little, push the back wheel back as far as it will go without over tightening the chain and making sure it is central to the frame tighten the bolts back up. watch to make sure it is not slipping.
then put it into a middle gear and turn the peddles if you hear rattling in the chain or it changes gear use a small screw driver to set the changer to the middle of the got and it should be quieter in gear.
also do this for the front changer and make sure it doens not go to far our as this will pull the chain off.
if not sure take it to a bike store and ask advise they will tell you whant can be done and how much it would cost.
Answers & Comments
Check that the back wheel is fitted correctly. is it wobbly becasue it is buckled, or because it is not tight onto the bike.
if the wheel is buckled then it should go to a store to be straitened depends on how bad it is .
if not put bike upside down and undo the back wheel nuts a little, push the back wheel back as far as it will go without over tightening the chain and making sure it is central to the frame tighten the bolts back up. watch to make sure it is not slipping.
then put it into a middle gear and turn the peddles if you hear rattling in the chain or it changes gear use a small screw driver to set the changer to the middle of the got and it should be quieter in gear.
also do this for the front changer and make sure it doens not go to far our as this will pull the chain off.
if not sure take it to a bike store and ask advise they will tell you whant can be done and how much it would cost.
I hope this was useful