Folks, I know this issue has been addressed, but I'm having trouble finding a good-fitting answer. If I want to change the gearing on my 2001 M900i.e. (for the normal desired effects), which is the best way to do it? Change the front, change the back, or a combination of the two? I am a commuter (including superslab miles) but also enjoy twisties. Losing some top-end speed doesn't bother me. That said, what size chain would I need to fit that particular set-up? Thanks.