Help please - rohloff gears!!

[RichardM]

PLEASE NOTE THAT I HAVE ALSO POSTED THIS MESSAGE ON THE THE 'TRANSMISSION' FORUM - I'M NOT SURE WHICH IS THE MORE APPROPRIATE

Hi

I’m hoping that someone on this forum will be able to help!

A couple of months ago I bought a second-hand Thorn Adventurer tandem with the rohloff hub (unfortunately the budget wouldn’t stretch to a new one!)  We are now in France, having caught the excellent bike-bus and then hired a car to meet up with family / friends in Provence.  The plan was to cycle back through the Pyrenees to take the ferry home from Santander – however, that is now beginning to look very optimistic!

The other day, whilst fully loaded, some of the gears started jumping for no apparent reason.  The gears that are most badly affected seem to be in the range of 4 – 7.  When I say they jump, there is a bit of a click that can be heard and felt through the pedals and the gear seems to change up or down a fraction of a gear.  It does not change into a completely new gear and there is no movement through the shifter.  (I think I have experienced a similar problem with a badly adjusted derailleur gear, but there the gear may change completely).  Yesterday, when we took the tandem out unloaded, the problem did not seem to be nearly as bad but today (again unloaded) it seemed to be getting worse again.

Since buying the tandem, I have taken it into Thorn’s workshop and Dave, their mechanic, has renewed the cables for me.  Dave also changed the oil and their wheel-builder has re-built both wheels (I am beginning to think that the bike has done more work than I was led to believe when I bought it – although I don’t think the seller would have intentionally misled us in any way).  I have tightened both cables slightly in case they have stretched but I don’t think this has made any difference – I don’t think it is a cable problem.  To my untrained eye, the chains and sprockets do not appear to be unduly worn.  (We had a problem with the chain skipping on our old tandem.  The problem then was worn chainrings – the symptoms this time are different.) 

I fear that the problem may lie with the internal workings of the rohloff hub.  I have read on this forum about the difficulty in changing between gears 7 and 8.  I think we have largely mastered the technique for this, but, even so, I think it is more temperamental on this tandem than it should be.  (A couple of years ago we test rode another make with a rohloff hub and I do not recall any problems with this – even though we were then complete tandem novices).  I suspect that the hub may have to go back to rohloff to be serviced but, in the short term, we need it to get us home!

Unfortunately, my mechanical skills are very limited – ironically this was one of the attractions of the rohloff – I thought that it was almost entirely maintenance free (save for the oil change) and trouble-free!

I think I have read on this forum of a member being advised (possibly by rohloff) to take out the rear wheel and then to hit the hub with a rubber mallet / shoe.  Perhaps as a last resort, this is worth trying??

Any advice or suggestions from those more mechanically skilled than myself will be greatly appreciated!

Richard

[Danneaux]

Hi Richard!

I have removed your other post, as the one here is most appropriately placed to get you the help you need in one place without fragmentation. Good idea to cover all bases, though! 

All sympathies your way on the present Rohloff hub "skipping" problem.

Yes, occasionally a user will have to give a short sharp rap to he axle end to re-seat the internal shims, but this seems to be indicated where the hub/wheel has trouble freewheeling and stops spinning shortly. While it doesn't sound like your problem, it wouldn't hurt, I suppose, so long as the mallet is soft-faced and the blow is not too hard in order to avoid damage.

It is possible another oil change might help, but where it has seen service and attention so recently from Thorn, I suspect it may indeed have problems beyond the obvious. I would suggest contacting Thorn/SJS cycles soonest to get their advice. Dave is on the Forum occasionally, but may not see your query immediately in the press of business, so a call wouldn't be amiss given your pressing need.

I know others will be along with suggestions shortly, so do check back to see what has been offered; perhaps something will provide the key to restore smooth running.

I am so sorry this has caused a cloud on what sounds otherwise to be a wonderful holiday on a new (to you) tandem bike. I do very much hope it can be resolved soon so you can once again have the full measure of enjoyment on your holiday.

Best,

Dan.

[triaesthete]

Hi Richard

first thing to do is slacken those cables back off! 

The slack in the cables is what allows the hubs internal detente mechanism to engage and hold the gear.  Cable stretch and slop at the shifter cannot affect the hub, but counterintuitively, a lack of free play can.

Good luck
Ian

[Andybg]

try disconnecting the cables and see if the problem is still there

Andy

[RichardM]

Thanks for your advice / suggestions.

Ian - I will try slackening the cables off again, in view of what you say but I don't think this is the problem.  I didn't attempt any adjustment to the cables until after the gear skipping had started - and even then it was only a half turn - the cables are still not what I would think of as taut.  It occurred to me that our panniers might be restricting the free run of the gear cables but I don't think there is any contact here and so this is not the problem.

Thanks for your help

Richard

[JimK]

When my cables were frayed a couple weeks back, I wasn't getting a nice sharp click or snap between the gears and for sure there was some iffiness in the transmission because I was often not solidly in one gear or the other.

Andy's suggestion, to remove the cables to see how the hub behaves that way, is excellent. But if you are not getting nice crisp snaps from one gear to the next, that would be a definite clue.

[Danneaux]

Richard...

In looking back over your initial post about using the bike bus and then the hired car to make it to your friends' place...

D'you suppose the cable *housings* might have gotten crimped in transport, restricting free cable movement? If so, I would look at the entry to the first cable guide, near the head tube.

Just a thought; it could be any number of things, but would be pleasant if it was something relatively simple, and this would explain why it seemed to work alright when leaving Thorn/SJSC and not later.

Again, disconnecting the cables would reveal if this was a possibility.

Hoping....

Best,

Dan.