Joined: Jul 2015
Posts: 7,236
Likes: 3,143
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
i watched a slow-motion vid of a chain derailling once... the chain did a crazy snake dance, both up-down, and sideways...then derailed ... absolutely crazy looking... the Front Derailleur USUALLY acts as a chain guide, but when shifting to the small ring, the "guide" is suddenly 4 inches in front of the chain meeting the sprocket, when considering chain travel direction......
A Clutched Rear Derailleur limits the crazy bouncing/whipping around, thereby reducing or eliminating derails.
i've considered using extra-thick bubble gum grease in the cage pivot, as a "Shock Absorber".... might be worth trying, eh?