Originally Posted by
kamtsa
When I change the right gear to 6, sometimes it changes to sixth gear and some times it does not. I it is kind of unpredictable. In some cases it even take 5-10 secs to actually shift. By deterministic I mean that if I turn the shifter to #6, it will always change immediately to the 6th gear.
Kam
It sounds like you need to adjust the rear derailer.
http://www.sheldonbrown.com/derailer-adjustment.html
In my experience, no internal hub shifts as well as a shimano cassette and tuned rear derailer; although some internal hubs shift well.