I recently swapped out the freewheel on mine from the stock 16 to the shimano 18t. I was originally going to get the 17t but my LBS didn't have it in stock. No worries, feels AMAZING. I can't stress it enough I love actually spinning not mashing. Mashing for me always felt terribly inefficient and never floated my boat. But 70 GIs=phenomenal for me.