OK I have been meaning to post this somewhere, so figured here would be as good a place as any.
Dura Ace 9000 gear cables suck, so for now, until they improve them, stay away.
I upgraded to DA9000 in April this year. I got it fitted to my SuperSix Evo by the shop. All good, and they did a perfect job. I have the SiSL2 with Spidering so did not get the DA9000 cranks, but everything else is DA9000.
After 3 months, the rear shifter cable snapped. Upon removing it, it was all frayed up and had snapped strand by strand over time, without me noticing, until it got to the point where I did notice (on a ride) then is fully snapped (on the same day as noticing it. It snapped about 2cm from the head of the cable. Remember that part.
I installed a 7900 cable to get me home, as the shop didn't have any 9000 cable inners in stock. I was running the original grey DA9000 cable set (brakes and shifters), so thought I would take the chance to throw money on the newly released black DA9000 cable set to match my bike. How frivolous of me.
I installed the complete new cable set, taking care to install everything perfectly, and with my usual OCD level of care. All good. It went in fine and worked great. For 2 months. Then the front shifter cable went the same way as the rear shifter cable. Started performing badly, then on the same day went 'PING!' and snapped. Same place, 2cm from the end. I got a spare inner from the shop, checked the full shifter, and outer cable path for anything that could be rubbing/snagging. Nothing. Installed it and it worked (is still working) fine.
Then 2 months after that (yesterday!), I was on another ride, and the rear shifter cable snapped a-f**king-gain. In the same way, in the same place. 2cm from the end. This was 3 months in total since installing it along with a complete new set of outers.
So, lets look at this.
Front and rear cables have been installed with 2 different sets of outers, by two different people, one a professional bike mechanic and one an obsessive 34 year old man with a life-long history of working with bikes. All snapped in the same way, in the left AND right shifter.
The rear cables have snapped with twice the frequency of the front, which makes sense, as I shift a lot more on the back that the front, so any friction issue is likely to cause damage faster on the rear than the front.
Now, when it first happened, I posted on the usual places and predictably a number of people did the whole 'you installed it wrong, etc. etc. blah blah' rubbish, proving how little faith they have in me. I was adamant that this wasa design issue, but they were not having it. So what.
Well, yesterday, I posted up on Facebook my annoyance at yet another DA9000 cable snapping, to which a pro-race mechanic who wrenches for Neil Pryde-Peugeot in Asia piped up and said he had been seeing this a LOT on his team as they use the mechanical DA for racing. He is convinced, like me, that this is a design flaw.
So, the 2cm bit... Well, I had a good look inside the shifter, and it seems the area 2cm under the head of the cable is the part that slides back and forth inside the actual shifter, on the channel designed to guide it. it doesn't go in and out of the cable outer, so this is most likely a design issue with the shifter / cable material combination, rather than some friction issue with the end of the cable outer, or that funny fluted thing you put on the end as it goes into the shifter body.
Now, so what, you are probably thinking. Well, I wanted to share how I now have my bike set up to deal with this, and also have been informed by the race mechanic that he is doing the same, to prevent you having the same issues I have been having.
I now run this...
Front and Rear Brake: DA9000 cables, inner and Outer.
Front Mech: DA9000 cable: Inner and Outer.
Rear Mech: DA9000 Outer. DA7900 Inner.
Have I noticed any difference in shifting on the rear? Not a single bit. Admittedly, the 200yen Stainless Steel Shimano cable I used to get me home yesterday was a BIT less slick the DA9000 it replaced, but after 'upgrading' this to a DA7900 cable, I can not notice the difference.
So, I would honestly recommend considering this, if you want to be able to fit and forget your cables, and not get stuck in the middle of nowhere with only 53/11 to ride home on.