Originally Posted by
ArgoMan
Hey all, I'm building out my TT bike anew with an 11-speed set up. I have a bead on a NOS Ultegra R6800 rear derailleur and a very good condition used R8000 RD. There's about a $30 difference, with the 6800 being the cheaper part. I see that Shimano incorporated a "Shadow" technology into the 8000 - I have no idea what that is. Any hoo, is there a big difference in the performance of the RDs? I don't mind spending an extra few bucks for the used R8000 if it will perform a lot better. Thank you!
Shimano has been using their 'Shadow' technology on their high-end mountain bike rear derailleurs (> Deore) for many years. In addition to the benefit described in the images below (from
here), Shadow derailleurs have a more direct housing routing near the derailleur, which results in a lot less cable friction, and therefore, better and smoother shifting. The whole purpose of the shadow tech is to reduce chain slap, which isnt a problem for pavement road racing. Further, the friction clutch adds a damper to the mass (chain, bouncing) and the spring (twist of the derailleur cage). The 6800 with new ceramic or aluminium pulleys can go on and on.