Replacing Rohloff shifter cables on a Raven Twin tandem

[HugoC]

Hello,

I'd like to ask the Rohloff experts we have on this forum a couple of questions:

1. The Rohloff instruction video for replacing the gear cables state that the cables need to be wrapped around the cable pulley before the Ex box is reattached to the hub. What are the possible consequences if the cable is cut short and is fixed to the pulley but NOT wrapped around the cable pulley before the Ex box is reattached? This may be the case with my Rohloff (long story.....) and the gear shifting works as expected. Could the only consequence be increased cable wear?

2. Has anyone had experience of replacing the Rohloff shifter cables on a Raven TWIN, which has cable spliiters? I cannot find any instruction on how to cut the correct length of cable for the 'front' cables. Does anyone  have any advice or tips?

Thanks in advance

HugoC

[mickeg]

I am not sure which hub you have, the EX box or the one with an internal gear cable. 

I think Ravens do not use the EX box.  But you said long story, so maybe yours is different.

I have the EX box, when I have installed cables, I cut them to the length described with the extra 200 mm inner cable.  I would not suggest anything else.

[HugoC]

Thanks for the prompt reply mickeg.

I can confirm that I have the EX box. These are fitted on the Mk 3 Raven Twins (tandems) by Thorn. I agree that the Rohloff guidance should be followed. However this may not always be the case and I'm interested in potential consequences of not following the advice.

Regards

HugoC

[mickeg]

So, if I understand your question, you would like to use a shorter length of inner cable than you normally would to obtain the 200mm of inner cable when you do your cable cutting.  And you would like to know what happens.

I have no clue what happens. 

Good luck.

[PH]

Hello,

I'd like to ask the Rohloff experts we have on this forum a couple of questions:

1. The Rohloff instruction video for replacing the gear cables state that the cables need to be wrapped around the cable pulley before the Ex box is reattached to the hub. What are the possible consequences if the cable is cut short and is fixed to the pulley but NOT wrapped around the cable pulley before the Ex box is reattached? This may be the case with my Rohloff (long story.....) and the gear shifting works as expected. Could the only consequence be increased cable wear?

It isn't possible for the shifter to be functioning correctly without the cable fully wrapped around the pulley. It's a 2 minute job to take the outer plate off and have a look, you'll see that if you've missed a turn there won't be enough rotation to get all the gears!
It's not a good idea to have the cables too tight, or slack, there's nothing in the system that needs to be under tension. If you find the inner has been cut a bit short, there might be some excess in the outer, cutting X of that is the same as lengthening the inner by the corresponding amount.

I'll leave your second question, I have an idea of how they work but have never used them.

[HugoC]

Thanks for reply PH. Given that I have all 14 gears then my LBS must have fitted the cables correctly!

Would still like to learn from the experience of others who have fitted to 'front' cables to the cable splitters, if there is anyone out there...........

[Danneaux]

Would still like to learn from the experience of others who have fitted to 'front' cables to the cable splitters, if there is anyone out there...

While I have not done so on a Rohloff-geared tandem, I did replace the front cables on a split cable run for a coupled road bike with derailleur gearing and don't see how it could be different with a Rohloff-equipped bike.

In this case the front cables were worn, not broken and the replacement was precautionary so I had intact cables to go by to determine cut length (recommended).

I simply undid the tiny little grub screws on each splitter, extracted the cables, and then removed the leaded ends from the shifters and measured each cable so I could cut the new cables to length. In this case, the bike had splitters supplied by Bruce Gordon, so the cable ends were first fitted to the shifters, then the ends were simply rammed home in the splitter's front wells, then resecured with the grub screws.

It seemed a simple task and the indexed gearing needed no adjustments after, so it seems I got the length right on the first try. The same should hold true with the forward cable runs on split Rohloff cabling. I wouldn't expect the Rohloff hub housing adjusters to need fiddling so long as the forward cable length remains the same.

One hearty recommendation: After cutting the cables to length, be sure to apply some clear super glue to the ends and allow it time to cure before fitting to the splitters. This keeps the ends from fraying under pressure from the grub screws.

My own tandem has unbroken cable runs (i.e. it has no frame couplers) so I use standard ultra-long tandem gear cables on it.

Best,

Dan.

[mickeg]

I have no clue what splitters you are talking about on your Thorn.  I have Ritchey cable splitters on my Ritchie Break Away bike (badged as a Raleigh Grand Prix).  The light gray thing under the word Prix on the frame in the photo is a splitter, the are two pieces of cable for that rear brake.  The splitter holds the two pieces of cable together.  And there are two other splitters under the down tube for the derailleurs.  The splitters simplify things when I split the frame in two halves.

I have never had to replace the cable, thus have no experience with that.  For that you need to rely in Dan.

If you have S&S couplers on your tandem, then perhaps SJS installed similar splitters to the Ritchey ones on your bike.  My Nomad Mk II is the S&S version, SJS included one splitter with the frame when I bought it for the rear brake.

[HugoC]

I've heard from another source that when fitting the front cables, after making sure the cable ends are seated correctly in the shifter, put the shifter in gear 7 and cut and secure the cable to the splitters so that when connected, the splitters are midway between the cable stops (when in gear 7). Then fit the rear cables to the Ex Box using the recommended method. I've made a poor attempt at showing this on a photograph - gear 7 has been selected and the position of the cable splitters is approximately midway between the cable stopes, i.e., X = Y. This seems to make sense. Would anyone like to offer their thoughts?

[UKTony]

I ve never installed a split shifter cable before but I was thinking about the process logically and came to the conclusion that one first cut a suitable length of outer housing for the front section between the shifter and the upper cable stop above where the splitter would be. Then fit the inner to the shifter and feed it through the front section of outer housing. It was how to gauge the midpoint that foxed me. I was thinking of putting in gear 6 or 7 or midway or midway between the two but wasn’t sure. Once you cut the inner and join the splitter, you then need to cut a length of outer housing for the rear section. Lastly using the 200mm gauge cut the inner to length and fit to the ex box. I think the key is not to try and measure and cut the front inner first. As I’ve said, I’ve never done this before but think this is the sequence in which I personally would tackle the job.

[mickeg]

.... Would anyone like to offer their thoughts?

If I knew how to do that the best way, and I don't, it would probably take forever for me to describe it without ambiguities.  Sorry, not going to try.

That said, if you are replacing cables without adding or subtracting any length to either of them, I would be very tempted to remove the old cables and carefully measure and cut new ones that are exactly the same length as the old.  Hopefully both (upshift and downshift) are exactly the same length so you do not have to worry about which is which.

If for some reason, you were adding new housing to change shifter location or something like that, if you could measure the exact length of the difference in your change, then add or subtract that difference?

[Mike Ayling]

I am not sure which hub you have, the EX box or the one with an internal gear cable. 

I think Ravens do not use the EX box.  But you said long story, so maybe yours is different.

I have the EX box, when I have installed cables, I cut them to the length described with the extra 200 mm inner cable.  I would not suggest anything else.

Hi Mickeg

Our 2012 Raven Twin tandem came with the EX box but cable splitters were not offered for the shifter cables. To split the bike using the couplers we have to remove the EX box and wind up the cables and attach them to the front half. There is a splitter for the back V brake cable

Mike

[GamblerGORD649]

So you cut the inner too short?? Then just cut the outer shorter.
My shifter is DIY on the top tube where there's no way for it to flop around and wear out.
Still not touched since installed 8 years/ 18,200 miles ago.

[mickeg]

...
Hi Mickeg

Our 2012 Raven Twin tandem came with the EX box but cable splitters were not offered for the shifter cables. To split the bike using the couplers we have to remove the EX box and wind up the cables and attach them to the front half. There is a splitter for the back V brake cable

Mike

That is the same exact thing with my S&S Nomad Mk II, except I am sure you have much more length.  I have full length outer housing for both brakes and both shift cables.

In the first photo, front frame member from my Nomad is under the wheel.  You can see the shifter and the disconnected EX box is in a plastic bag under the tire, I can see some of the plastic in the photo from the bag over the EX box.

I have not used the brake splitter, did not understand how initially and I misplaced it, when I found it several years later I did not feel any urgency to add the splitter, thus still not used.  I might use the splitter next time I pack the bike in a case, but have no plans to fly with my bike for at least another year. 

It is not clear in the photo, but my brake cable is still attached to brake levers on my handlebar, which is next to the case on the right.

Unlike most, I use drop bars on my Nomad Mk II, second photo.  Drop bars do not pack very easily in a S&S case.