Asked my Honda dealer about getting a 42 tooth rear sprocket but he was unable to find a source either in the Honda or aftermarket parts list. I have searched these forums and found mention of 42 and 45 tooth sprockets but have not yet been able to find a source for obtaining one. Any comments regarding the 42 or 45 tooth sprockets would be appreciated. I have already installed the 13 tooth front sprocket but am wanting yet lower gearing.