South Fulcrum

I think I might have a rather specific problem. None of my searches came up with anything. So I'm working on a Shimano 3-Speed Nexus hub. The owner bought the bike new a little less than a year ago. It is shifting fine. However, if she keeps it in 2nd for a while it will start making noise like the chain is about to fall off. Sometimes it slips down to 1st and then pops back up. She has taken it to the shop where she bought it a few times, but they have just made it worse. Any ideas?

South Fulcrum

So no ideas?

motorhommmer

I would start with the obvious. Check cables tension and settings. Check shifter and perhaps put a cable tie onto the cable for a test sping to make sure it cannot move. It would appear that something is shifting or moving to allow chain etc change. Has the correct chain been put on. Is the hub adjustment correct. I would try and elminate all the obvious ones before getting serious and perhaps send the hub back to Shimano

Brian

Retro Grouch 

I would examine the cable housing ends. If you see a wire or two sticking out, that's it! The housing is squishing down and becoming shorter which upsets the shifting adjustment. Readjusting the shifting works for a little while, but the cable housing keeps shrinking and the problem keeps coming back. Trim off the damaged end of the housing, slip on a new housing ferrel, put everything back together and you'll be good-to-go.

South Fulcrum

Thanks! However, I have been reluctant to take the off since it seems to be shifting fine and hitting all the gears. I understand the logical conclusion for the slipping to 1st is that the cable is loose. It shifts to 3rd just fine and the little red indicator appears to be spot-on.

Using the cable tie sounds like a good way to troubleshoot.

Or, is this just one of those things that you can never find exactly what is causing the problem, but if you take everything apart, clean it and put it back together, somehow the problem gets solved?

motorhommmer

I would suggest you look at the tip on cable ends and go slowly but carefully through everything