i have measured the id of the chainring and the crank and i got 9.5mm which roughly equates to 3/8 of an inch. i can buy 3/8 bolts and i think that it should be close enough so there is no movement. also i would normally consider using bottom bracket spacer or buying a smaller bottom bracket as other have suggested but I am using a press fit bottom bracket that can't be any smaller so my only option is to move my sprocket inwards.