well it needs tightening thats for sure. have you checked for tight and loose spots yet? the chain might be stuffed and youve found a loose spot while a tight spot might still be in acceptable range.
im not sure on the exact measurement of slack you are meant to have on the chain, i think its about an inch or 2.5cm
im not sure on the exact measurement of slack you are meant to have on the chain, i think its about an inch or 2.5cm