its not hard, but you may have to break the chain to fit a larger one on.
if you want to gear down your bike (more acceleration/less top end) i recommed just go down one or two teeth on the front sprocket. that way you can just replace the front sprocket and use the stock chain and rear sprocket, and its the easiest install. btw, 1 down on the front is like 2-2.5 up on the rear.
it increases the strain put on the tranny. BAD news for bikes with tranny waekness already. Its just as easy to go up a few in the rear vs going down 1 in the front. It is simple to swap them out too by the way. i was 9 then 6 up in the rear and no problems
oops read that wrong. i thought he said that just changing the rear was bad for the bike. -1 in the front shouldnt put too much strain on the tranny, but dont go down too many or you'll make your chain turn too tight