Critical failures in the 9000 design.
Pro set up Columbus Genius, DA 9000 11 speed, 39/53, 12-25, internal routing, Zipp 303 tubulars. Worked like a charm for 900 kms. Then the rear cassette issues began, uncertain if a cog or the chain or why would it struggle on one disk (18t) specifically? Clank noise resonating in the frame (BB?) No we checked without the chain. Up or down gears no matter. My Gianella specialist (Montreal) changed the DA cassette twice, set it up several times, the issue came back.
Part of the shifting issues: the 'Polymer' coating had began unraveling inside, at contact points, and coiling around the rest of the cable, changing aspect and thickness of the cable. With a new uncoated stainless steel, lubricated cable, shifting issue resolved.
In the end, the 'polymer' coating is a gimmick that is condemning the rider without knowing. In contrast, the 'BOA" steel lacing system, on shoes worn 7000-10000 kms, it is also coated in a tiny plastic and NEVER unraveled itself. At similar look or feel, this critical Shimano component will fail the rider when it comes to one thing: gear shifting. The steel cable is intact, it is the polymer failure specifically that fails the steel contained within. Seeing the sections next to the lever where it unraveled and coiled (COILED) on itself, one could not even see the metal pattern underneath, and the gear issues became clear. Drag was local, and shifter position / gear issues were associated only with the location of the polymer blockages.
In addition to the cable, the 11 cassette spacing may be too narrow for a standard crankset (angle of chain and CN-9000 thickness). Once the chain is on 53/18t, the angle and tolerance changes, favouring unnecessary rubbing and grinding (Shimano admitted this a few weeks ago, see the bikerumour article on the new upcoming DA 9000 cassette). Particular care is required to keep the chain soaked to the point of it gliding across the engagement teeth on the nearby 17t. That aside, none of it changes the chain whips I get occasionally under load, 18t and higher.
More, the technician must adjust the derailleur angle relative to the plane of the cassettes, adjusting or bending the hanger on the frame, neutrally, positive or negatively. Turns out the DA requires a slight positive (Shimano recommends neutral); however, the chain is slightly twisted on the cogs. The higher the chain tension (53 17t/18t) the more likely it will skip or grind. On the 18t the chain 'rests' on the left side of the 17t and moves up and down along its engagement teeth, even though on the 18t, and this oscillation is accentuated by the spider oscillation. 21/23 are not a factor as, by then, the size of the cog is sufficient to keep the chain clear from the nearby smaller cog and often one drops load and tension going down on the smaller chainring (36 or 39).
But these default issues (Polymer cable flaw, Chain perhaps to thick for cassette or cassette space tolerance too low, etc), forced this rider for weeks back at the shop. One culprit- the cable- was gradually annoying. Sufficiently working to mask the symptoms, but failing in actual usage. Failure means poor to no riding, and hence the one star.
Gear shifting resolved, the cassette issue is critical- as a riding and safety issue. 18t, 19t 21t sound as if they are worn out about to die (2nd cassette in a week) Yesterday, 06 Jul, brand new cassette, the chain nearly jumped out twice under load, 18t or 19t. Grinding/moving, the carbon spider section flexes, is too close to 17t, and the chain is literally shaken and vibrating until a critical oscillation may throw it off that cog. The metallic bang that ensues is quite concerning. SRAM 11 is my next bet until the new cassette is released- the bikerumour article.
Rider: 173 cms 73 kgs, 350-400 kms / week, rest speed 30-32 km/hr, cruise 35-36, faster pace (10 k sustained) 40-43km/hr.
Current usage: 1800 kms/2 months.
Previous systems used: 105, Ultegra. Issues- nil