Cycling UK Forum

Hi everyone,

I wonder if anyone has any suggestions or ideas. I have this rather splendid French post bike that I want to use for mainly local trips, but maybe for some more interesting touring too as its got great front and rear carrying.

The problem is the gears have had it and I am stuck.

They are Shimano Nexus 4. There doesn’t seem to be much on the net about them and what there is shows them to have been quickly upgraded by Shimano....I guess I've found out why.

I have taken them to my excellent LBS and he has tried the special Shimano oil and tried what he knows on them and suggested running the bike for a couple of hundred miles. I’ve done more than that now and no progress.

Problem is I only get two of the four gears working. I’ve looked at and set the cable lengths, the changer clicks into four positions and so I am fairly sure its internal in the hub.

I feel it's time to replace the existing. So thoughts are to just try and change the hub, maybe for the Nexus 8, do I just buy a new hub and changer and swap this into the wheel (how?)? Can I buy a complete wheel with a new hub? Should I try and change it for a mountain bike type wheel and stick derailleur on there or any other hub system? Anyone got any bits for sale???

Any thoughts would be very appreciated as I love the bike and want to get it to a useful condition and use it. If I am going to spend money and time then I would like a reasonable range of gears of course.

Points to consider, it’s a 26inch wheel and has a hub brake.

Thanks to anyone who might be able to help.

I am pretty sure I have a nexus 4 internal here so that could be a route forward for you. PM me if you want to buy it; this will at least get you going again.

These hubs are not terribly complicated inside but because parts are not readily available, you can't fix them easily if they break. They normally go on for years though. The few I've seen that have stopped working well did so because water got inside.

BTW you need the right shifter (for Nexus 4 speed, pulls about 5mm per click IIRC) and you need the right cassette joint too. If you have the wrong external parts it won't work.

If you change to another IGH (or derailleurs) in the long term, you need to fret about the width in the dropouts; not all hubs will fit, or can be made to fit even.

cheers

Thanks Brucey,

The shifter is the original so I asume its the correct one.

To be honest I would rather keep the hub original too for the moment (so PM will be sent re: your bits, if you pardon the expression). It could well be water in there, firstly because its clearly been used outside and secondly because it was left outside!!

What do you mean by the right cassette join? The external parts are a bit of as bodge to be honest!

I fixed a spring on it to get it to return...oh dear...dare I show you a picture....ok....don't laugh !!....this is the troublesome area !

ah.... if it needs that additional spring to return then this is a pretty good sign that all is not well internally (or perhaps the cable is binding). I've pm'd you re. a good centre.

[BTW It occurs to me that I also have a rough centre that has mostly good parts in it; if you want a spare centre too, maybe one could be built up from the remains of your present one and the rough one that I have].

The other thing that you might be interested in is improved lubrication for these hubs. I may be able to help you out there, too.

cheers