Starting with the Rear Derailleur and the Front Derailleur in this blog post, I will mainly be highlighting the physical differences found between Ultegra 6800 and Dura-Ace 9000. This should give a good idea on whether it is worth paying the price difference to upgrade from Ultegra to Dura-Ace.
Dura-Ace 9000 RD and Ultegra 6800 RD. Both are short cage versions.
Similar construction, with an aluminium outer link and inner link.
Carbon pulley cage on the Dura-Ace RD for weight savings, as compared to aluminium cage on the Ultegra RD.
Full hollow titanium B Axle on the Dura-Ace RD, as compared to the Ultegra RD which only has a small hole on the stainless steel B axle.
Both the pulleys on the Dura-Ace RD uses sealed bearings, while the Ultegra RD uses bushing for the upper pulley, and sealed bearing for the lower pulley.
197 grams for the Ultegra 6800 Short Cage RD, which is a nice low weight
The Dura-Ace 9000 RD goes one step further and is even more lightweight, at only 160 grams for the short cage version!
Moving on to the Front Derailleur, let's compare the Dura-Ace 9000 FD with the Ultegra 6800 FD. In this case, I am comparing the braze on version of the Dura-Ace FD with the clamp band version of the Ultegra FD, so the weight comparison will not be accurate.
Dura-Ace 9000 FD on the left, Ultegra 6800 FD on the right. Similar construction.
The surface finishing on the Dura-Ace FD is smoother than on the Ultegra FD. Both have the plastic skid plate on the inside of the chain guide.
Similar rear view. Dura-Ace FD on the left has an aluminium chain guide for weight savings.
Different cable fixing bolt design. Dura-Ace FD on the left has a special notched spacer to clip onto the two cable fixing positions, while the Ultegra FD uses a standard round spacer under the cable fixing bolt.
Dura-Ace FD on the top, with a screw linking the outside and inside of the chain guide. This screw is to allow the FD chain guide to be opened up, which will allow the chain to be removed or installed on the bike without breaking the chain to pass through the FD.
Clamp band type of Ultegra 6800 FD, weighs 105 grams.
To get a more accurate weight comparison of the Dura-Ace 9000 FD, this clamp band adapter should be fixed to the Dura-Ace braze on FD. This adapter weighs about 20 grams.
Weight of Dura-Ace 9000 braze on FD + clamp band adapter is 85 grams, still lighter than the Ultegra FD
My conclusion is that the main differences between Dura-Ace and Ultegra RD and FD are the weight and surface finishing. Dura-Ace components are more lightweight and also look better with top grade anodizing. However, Ultegra components cost only half of Dura-Ace, and yet has almost the same performance as Dura-Ace. The sensible and logical choice is Ultegra, but if you can afford it, go ahead and get Dura-Ace if that is what makes you happy.
Next up, the crankset of Dura-Ace 9000 and Ultegra 6800 will be compared.