Originally Posted by Russ Roth

You'll need to adjust the high and low limit screws on the rear der, but you can even use the same chain if it isn't too stretched. Not certain why your frame would already measure 130mm, probably someone screwing with it in the past, but the der should handle the 7 speed cassette, barring, as someone else mentioned, the low cog being too large for the der to wrap the chain around.