I'm disappointed with my new Cannondale and it's 105 group, I expected this to be a major upgrade from my previous trouble free bike with the bottom end group set. It's done about 500 miles, had new cables, a new chain and rear derailleur re-alignment and numerous adjustments over the 5 service visits between 2 dealers and it still doesn't shift smoothly every time. Over a 2 hour mixed terrain ride it will miss-shift several times.
It seems to be mainly an issue with the 3 black colored gears in the center of the cassette, regardless of small or big chain ring. Sometimes when up or down shifting the lever clicks as normal but the chain does not move to the adjacent gear, click again and it moves and stays there until the next shift. Other times I would down shift in anticipation of a hill, the chain appears to have moved, but when I stand it slips.
Both of these issues happen randomly and spoil my riding pleasure, does anyone have any thoughts on what the issue might be?