Hi, I have an UM 36 going well since last November, up to about 300 miles now. Only issue is that the 14 tooth top gear ring on rear sprocket combined with 40T on chainring is not fast enough. It seems to be from the shimano "tourney" range, an MFTZ06 sprocket with 14/28 teeth. There seems to be no 6 speed alternative with shimano that goes lower on teeth. However there is a 7 speed MF HG50 11/34 (34 being a "megarange" up from 24 in second gear. ). I would obviously have to change to a 7 speed shifter, as well, but my question is whether the 7 speed will fit in between the frame mounting points,because I assume that a 7 speed freewheel must be wider than a 6 speed by one chain thickness. Can anyone advise if this is true? Is there a way for me to get a faster top gear?
thanks
Jonathan.
thanks
Jonathan.