I want a little more top end on my Cruiser. I've already put on a 52 tooth front chain ring up front. There is a 14 tooth rear cog on my Shimano Mega Range 7 speed. I was told that 11 tooth cogs used to be available for them but I haven't had any luck finding them. The LBS's all told me that they've been discontinued Any one know where I could get one, heck I'd even settle for a used one at this point. I keep running out of gearing on the flats.