Help! Nexus shifting problem

[danfoto]

I have a 2023 Gazelle Grenoble C5HMB with a Nexus 5 rear hub and the usual twistgrip change. The bike's done just over 2600 miles. Every now and then, and for no obvious reason, it decides not to change up. Say I start off in 2nd, pause my pedalling and change to 3rd, nothing will happen except the twistgrip indexes to position 3 without encountering any resistance. Same again if I then change up to 4th then 5th. I'm still pedalling away in 2nd.

When it does this, I usually keep going, indexing the twistgrip down and up until eventually the hub decides to engage 3rd, which it usually does smoothly even when I'm pedalling hard on a hill!

I discovered today that when it does this, the "cure" is to stop, and press down on the arm to which the gear cable attaches at the hub end. It's like the "return" spring on that arm isn't strong enough to overcome the resistance in the cable?

Anybody know how to cure this please? A generous spraying of GT85 around the offending area made no difference ...

 

[matthewslack]

Maybe establish if there is excessive resistance in the cable? Have a good look at both ends, if possible disconnect and slide the inner in and out. If there is a problem it should become clear.

Cables sometimes fail one strand at a time, and the broken strands can cause all sorts of trouble.

 

[danfoto]

Maybe establish if there is excessive resistance in the cable? Have a good look at both ends, if possible disconnect and slide the inner in and out. If there is a problem it should become clear.

Yes, that's the plan tomorrow if I get a chance. Are bicycle cable outers usually PTFE (or similar) lined nowdays?

 

[Nealh]

Check the yellow marks on the nexus cassette joint are aligned when the 1:1 gear is selected.

 

[danfoto]

Check the yellow marks on the nexus cassette joint are aligned when the 1:1 gear is selected.

Ah! I thought they were supposed to align when in the middle gear (in this case 3rd)?

 

[Nealh]

The 1:1 gear varies dependant on the nexus model.
I thought the 1:1 on the nexus 5 was gear 1 as the nexus 5 was designed for ebikes, the other gears being higher over drive gears.

My Alfine 8 has gear 5 as the 1:1.

Otherwise as Matt has said check for any line kinks or freying.

 

[Nealh]

It uses a thicker viscosity oil then the alfine 11 so may be it may need a service /oil change ?

 

[danfoto]

It's not the cable. The arm to which the cable attaches at the hub isn't moving back anti-clockwise after an upward gearchange without a good poke on the end of it.

I guess sorting this out isn't possibly a DIY job?

 

[Nealh]

The arm on the hub is called the cassette joint to which the cable via the rubber bellows section attaches to the hub , the inner moving part of the cassette is the cassette pulleyb of the cassette joint.
The arm it self should remain perfectly staionary and not move .
The cable passes thru the cassette arm /bellows and the near the end of the cable tightens to a cable mounting nut/clamp , the nut/clamp and the cable partly wrap around the top of the motor until the cable nut slots in to the appropriate mounting posistion on the cassette. The cable at the top of the hub is held by a guideway.
The only moving part at the hub end should be the cassette pulley to which the cable activates for a gear change.


SHIMANO NEXUS INTER 5E SG-C7000-5V SERVICE MANUAL Pdf Download | ManualsLib

 

[Nealh]

DIY wise the nexus or Alfines are user freindly to disamntle and reinstall.
I oil bath and service my own to an extent ( I don't dismantle the moving main innerds but do remove the unit as whole form the hub body to clean both parts up).
The cassette fiitng parts can be a bit fiddly but not hard to remove or refit.

The cassette fixture of the hub may need removing and refitting , grime /grease/detritus may be hindering movement so may need a good clean up as well as an inpsection of the bellows for free cable movement.
After 2600 miles it probably won't hurt to have the hub redrained/cleaned and relubed with oil.

 

[danfoto]

Thank you very much indeed for your help, nealh. Probably going to be Sat or Sun before I get to look into this further, but I'll be sure to report back in due course ...