Non-mechanic here. I am usually one of those "commuters who only maintain something when it breaks". But knowing that about myself, I just bought a close-out 2007 Giant Cypress EX, which has the Shimano Nexus 7-speed internal hub, no integrated brake. (The bike comes with sidepull rim brakes.) Generally I am pleased with it, especially given that we have had snow about half the days last week, the bike's first week of use!
I have noticed a slight shifting issue that I have seen referred to elsewhere but would like more input on. Others have referred to it as "missing" or "skipping". When I shift, sometimes it's like I've shifted into a lower gear even though I'm in the higher end, until I adjust the twist shifter slightly and then I get the gear I was expecting. I think it might happen more often while upshifting than downshifting.
I'm not an expert rider, and my previous experience with an internal hub is limited to an old (no idea, maybe 1960's or '70's?) Shimano 3-speed on a Huffy that I got for $3 at a yard sale. So I'm willing to accept that part of it might be my getting used to the shifting style. I realize that I have to stop pedalling or at least ease up on the tension when I shift, so maybe as my technique improves I'll get better at avoiding the problem, or at least learn how to work around it. It might be that with the twist shifter, I haven't gotten the knack of how far to rotate it for a single gear yet. (The weather has been such that usually I'm too busy concentrating on the road and/or the traffic to look at the shifter when I use it.)
But since others have referred to this problem, do you think it's also possibly a mechanical deficiency of the hub itself? If so, is it widespread on all hubs of this model, or could I have gotten a dud that might be able to be replaced?
Originally Posted by MadfiNch on Commuting forum
What's the point of a bike if you can only ride it on weekends, and you can't even carry anything with you?!
OK, go to this link and click on the "Service Instructions". In that PDF file you'll see a picture like this:
(this is actually from the service instructions for the Nexus 8, but the picture is almost identical. Anyway, you are now looking at the service instructions for the Nexus 7, if you followed the steps above)
This should give you clues about how to adjust the shifting on your hub. Read the doc carefully, look at the pics and look carefully at your hub. It may be (I am sorry, don't remember anymore) that you'll have to remove the snapring and the sprocket in order to see the coloured dots align on the cassette joint. This is your homework now. But this is the part that needs adjusting in case of shifty shifting on the Nexus 7 and 8.
If you have to remove the snapring, be advised that it'll shoot off at very high speed. Take some precautions so that it doesn't gouge someone's eye out. It's a ***** to put back, too.
I made a tool taht makes removing and putting back of a snapring a snap (almost), but you don't have that tool so for you it will be hard. This may be a good reason to actually ask an LBS to help out.
Last edited by wroomwroomoops; 12-16-07 at 08:28 AM.
Yes...the LBS you bought the bike from should be able to do any adjustments for free. Might as well have them check the bike over while you are there. Cables do stretch a bit on a new bike and need to be adjusted after a period of time. A bit of lube in the cable housings can make shifting or braking smoother or easier.