Sprocket size question ?

[jdepp]

Can someone explain to me why going to a rear sprocket with less teeth (say 52 to 49) may require a longer chain ? Wouldn't a 49 tooth sprokect be smaller in diameter than a 52 thus actually allowing more room for adjustment. ie. have more slack in the chain not less ? What am I missing here ?

[Psychoholic]

you have it right. Only problem you might have is having too much length to the chain and you might have to take out a link