More than any other drivetrain, an 8 speed hub really doesn't require its user to be a "bike person." An avid cyclist will certainly enjoy it -- as many of you have discovered for yourselves -- but anyone who can push the pedals will benefit equally from the utter simplicity and rock-like durability of this transmission. Combine the system with a chaincase and in a year of riding you'll probably do no maintenance whatsoever. You won't even have to wonder whether or not to feel guilty about it.
This brings us to the educational kernel nestled within this husk of a post: adjusting your Shimano Nexus hub. At this point, you might reasonably grow apprehensive that I'll try to explain planetary gear systems, expose you to exploded views, or start talking about gear inches. I won't. Adjusting your hub is a simple and easy procedure that will likely take less than five minutes and won't get your hands very greasy at all.
Step One: Diagnosis
When I teach a repair class, this is typically the subject that receives the strongest emphasis. Without understanding what's causing the problem, we can't fix it. Bearing this firmly in mind, we'll quickly check the three main parts of the system: the shifter, the cable, and the cassette joint (I'll explain in a moment). The cable will come first, because it's the simplest part of the system and -- relatively speaking -- the most vulnerable. Around three out of four "mis-shifting" or "gear slipping" issues on our bikes have the same simple cause:
Here, the cable housing (the outer sheath) has been tugged out of the shifter, exposing the cable. It has then caught on the edge of its proper place (the barrel adjuster) and failed to snap back in. This 1/4" difference leaves the system totally out of whack. The solution is even simpler than the problem: just nudge the end of the housing back into the barrel adjuster, and the tension already on the cable will do the rest, snapping it back into place.
If all is well so far, check over as much of the shifter cable housing as you can see for damage or kinks that could cause it to drag or bind.
Next, we'll move on to the cassette joint. This is the little plastic unit on the side of the hub where the cable attaches, and that translates your pull on the cable into the actual gear change in the hub. If you have a cloth chaincase (any Workcycle, Azor, or Jorg&Olif except Secret Service, Fr8, and Bakfiets) you'll need to open the back end just a little to see the cassette joint. Unsnap the outside snap, then slide the clip out of the pockets on the inside.
Gently peel the rear section of the chaincase up and forward, and tuck it out of the way.
Now you'll be able to see the gray and black plastic cassette joint, and the little adjustment window with a yellow indicator line. With a plastic chaincase you'll just be able to flex it inward slightly, and the view will be the same.
Now that you've ruled out problems with the cable, shift into fourth gear (you'll see a dot next to the number to tell you it's special) and check the yellow marks in the small window on the top of the cassette joint: if they line up, you're adjusted properly. If they don't, then turn the adjuster on the shifter (with a couple of experimental turns to make sure of your direction) until they do.
...And you're done! You've just done exactly what a good mechanic would have when confronted with Nexus hub "issues," and almost assuredly resolved them. Take the bike for a quick test ride, and enjoy your perfect shifting.
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