Originally Posted by SpeedyStein

A little light lube in the cable housing might help too - especially useful for un-gunking rear der. loops, although I doubt a new bike with full length cable has gunk buildup in the cables. Perhaps the rear der. adjustments are way off - have you checked the limit screws? You might try disconnecting the cable altogether and feeling for yourself just how much friction is in your cable setup. Also a thought - is your cable connected to the anchor bolt on the correct side - this can impact the pull ratio and jack up your indexing if the cable is anchored incorrectly. For rear derailer cable tension adjustments, I would stick to the barrel on the derailer itself and avoid the inline adjuster - they simply dont hold tension as reliably as a barrel adjuster. Jagwire and Ritchey both make good barrel adjusters that mount directly to the shifter too, if you want an adjuster within reach while riding - Jagwire Rocket I think it is called.


If the above all checks out OK, I would try to start over completely with adjustments. Disconnect the cable from the rear der., tighten the barrel adjuster all but 1/2 turn in, check the high limit screw, re-set the cable end into the shifter, cycle shifter to smallest cog position, pull cable taught and reconnect to rear der., then while pedaling shift up two cogs larger, and increase cable tension while pedaling still until chain just starts to skip on next largest cog, then back off tension 1/2 turn. Ensure that you can shift through all cogs, and check the low limit screw and B-tension screw. This method works for pretty much any Shimano setup, assuming shifter/cassette/derailer are meant to play together.