I seem to be "uninformed" on WHY, it's a faux pa to have the "so called", Dork Disc on the rear wheel!! I thought it was there to keep the "chain" from over riding the largest cog, so you all are saying, "it's not needed"?? So I take it that you all are saying that the "derailer" never goes so far out of adjustment that the chain can't override the largest cog?? If it's not needed, why does the mfg'er. of every bike made it seems put one on?? I'd like to be "enlightened" so let me know, thanks!