What are the correct granny ring spacer washer size for the chainring bolts for a shimano xt FC-M730 crankset? It is fine in the first 3 tallest rear cassette gears but it then the chain starts to rub on the middle chainring on gears 4 to 7 smallest cogs (7 speed cassette). I could tell you what is on there now but I'm about 9000km from the bike at the moment.

edit: dang autocorrect title...