Author Topic: Gears and cable changes  (Read 521 times)

slogfester

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Gears and cable changes
« on: August 02, 2019, 12:31:40 PM »
Hi, newbie to forum here. You guys seem to have a wealth of experience with rohloff hubs and I've read most on gear cables. But...

My gear hub cable (internal box) recently broke after 14 000 km (c. 5 years.... with 1 + 2 years unused in storage :( ). Replaced with new Easy cable set with -what I thought was- no issues. When I re-attached to the shifter cables via bayonet connectors I have lost gear 1. Disconnected and checked manually via pulling hub cables and I have 14 there, so its a shifter issue easily fixed by adjusting barrel adjusters. Or so it should be if *** ******** had supplied the bike with 1 or 2 turns slack from full length when new. This has never been an issue before as I have never needed to adjust the gear change and if it was, I always assumed that the shifter cable inners would stretch over time giving me back the slack I needed. I'm assuming that the hub cable HAD stretched over time and hence the new one is slightly shorter/tighter. Basically it seems  I've got no gear cable slack to play with.
Is the only option to replace the (fully enclosed) shifter cables and cut them c. 2? mm longer? Inner and outer? I was thinking of doing this anyway as a follow up (but at my leisure in the winter) and have already purchased new shifter inner+outer cables, but on other threads I have read some horror stories about disconnecting the female bayonets, so I will have to purchase them too and keep old ones as spares.
Or can anyone suggest another work round?
Many thanks
« Last Edit: August 02, 2019, 07:08:49 PM by slogfester »

geocycle

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Re: Gears and cable changes
« Reply #1 on: August 02, 2019, 08:53:37 PM »
Hi, newbie to forum here. You guys seem to have a wealth of experience with rohloff hubs and I've read most on gear cables. But...

My gear hub cable (internal box) recently broke after 14 000 km (c. 5 years.... with 1 + 2 years unused in storage :( ). Replaced with new Easy cable set with -what I thought was- no issues. When I re-attached to the shifter cables via bayonet connectors I have lost gear 1. Disconnected and checked manually via pulling hub cables and I have 14 there, so its a shifter issue easily fixed by adjusting barrel adjusters. Or so it should be if *** ******** had supplied the bike with 1 or 2 turns slack from full length when new. This has never been an issue before as I have never needed to adjust the gear change and if it was, I always assumed that the shifter cable inners would stretch over time giving me back the slack I needed. I'm assuming that the hub cable HAD stretched over time and hence the new one is slightly shorter/tighter. Basically it seems  I've got no gear cable slack to play with.
Is the only option to replace the (fully enclosed) shifter cables and cut them c. 2? mm longer? Inner and outer? I was thinking of doing this anyway as a follow up (but at my leisure in the winter) and have already purchased new shifter inner+outer cables, but on other threads I have read some horror stories about disconnecting the female bayonets, so I will have to purchase them too and keep old ones as spares.
Or can anyone suggest another work round?
Many thanks

Have you checked the orientation of the new internal cable in relation to the hub plate? On my Thorn the plate is set to about 10 o’clock to give the shortest route to the bayonets. I once got this wrong and set it at 12 o’clock hence the cables were too short.
 

slogfester

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Re: Gears and cable changes
« Reply #2 on: August 02, 2019, 09:58:04 PM »
hi geocycle,
Thanks. Yes I have tried rotating it c. 30 degrees either way (I have the plate with 12 holes: https://www.sjscycles.co.uk/hub-spares/rohloff-aftermarket-cc-oem2-axle-plate-converter-for-speedbone-8227/) but this just makes one cable much shorter and obviously out of line with the left chain stay mounted dual barrel adjusters.

PH

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Re: Gears and cable changes
« Reply #3 on: August 03, 2019, 01:08:50 AM »
I'm not sure I've quite grasped the issue, before doing anything else, you need to determine if the problem is on the hub or shifter side.
First thing is to check that all the cables are firmly seated in the ferrules - I once wasted a whole afternoon by not doing this :-[
At the hub end not only do you need to access all 14 gears, in 1 & 14 the lengths of the cables should be reversed, when you've pulled one to it's extreme the short length should be the same length as when the other is pulled to the extreme.
if all is well at the hub end and it's just a case that the cable is short, it's easy enough to replace.  Assuming the outer reaches where it's always done so, it shouldn't need replacing (Though you might be surprised  how fresh cables can improve the shifting) If it's just a bit more length on the inner, you can either replace it, or cutting some off the outer effectively lengthens the inner, maybe you could lose a bit from the radius from bars to frame?   
I know it can be frustrating, but keep calm and think it through, the problem can only be one of a few things.

slogfester

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Re: Gears and cable changes
« Reply #4 on: August 12, 2019, 11:12:05 PM »
Many thanks for your replies and suggestions. I have been busy thinking and tinkering. I've fixed my immediate problem (unable to engage gear 1), but I am not sure of the long term consequences and I now have to face another potential problem...

I finally got my gear 1 back. The clue was that when setting the cable pulley groove in the recommended 9-10 o'clock position on the shifting shaft, hub cable 1 was significantly longer then hub cable 14 when in gear 8. Hence, when pulled to full length to try and engage gear 1 it would be stopped by the (gear 1) barrel adjuster mounted on the left chainstay. Unwinding the barrel adjuster would simply make the shifter cable too tight and hence the gears would not work at all. So, the only way I could fix this was to rotate and set the cable pulley groove c. 60 degrees anti-clockwise to the c. 8-9 o'clock position. This equaled out the lengths of the hub cables when in gear 8 and hence gave me enough room to JUST clear the barrel adjuster and engage gear 1. The Rohloff instructions and video state that the hub cables should be equal length when in gear 8 and to adjust if not, but they don't say how to? Especially as I just purchased the 'easy hub cable set' which are pre-wound/cut? I read that if the the cable straightens out to the hole where it emerges from the pulley centre, it will quickly fatigue the cable. But I am not sure if this is happening on mine? The gears work fine and are indeed already a lot smoother than before, even before I attempt to complete the job by changing the inner+outer shifter cable...
Ever since I purchased my (new) bike, I wondered why one barrel adjuster (gear 1) was rather crudely sawn off  by the manufacturer/assembler (see pic 1). Well now I can guess why. They too faced the same problem of the hub cable reaching the barrel adjuster? Its root cause? The hex nut which the pulley sits on is set slightly out of alignment (hence 9-10 o'clock on mine is more like 10-11 o'oclock) AND/OR the distance from the centre of the rear axle to the centre of the barrel adjuster mount is less than the recommended 240 mm (chapter 7.2.2 / pg 79 of manual) (see pic 2). There is just not that much wiggle room. The cable has always been tight making connecting the bayonets always a struggle. The barrel adjusters were fully wound in when I received the bike and I have never been able to adjust them because -evidently- the shifter and hub cables never stretched. I've always wanted 1-2 mm more slack to free up the shifter and to make bayonet connection easier.

So what to do if , as I will have to eventually, fit new inner/outer shifter cables? I have purchased the cables, new female bayonets and new barrel adjusters just in case. Do I cut the inner/outer shifter cable the same length and replace like-for-like, or is there some way I can mitigate the problem by altering the lengths, i.e. the barrel adjusters would normally sit half wound out.
To me it seems the root cause is the barrel adjuster mount being welded too close to the hub!

I hope you're all still awake, followed me, and can make some suggestions.

Thanks very much
« Last Edit: August 13, 2019, 08:48:36 AM by slogfester »

macspud

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Re: Gears and cable changes
« Reply #5 on: August 13, 2019, 02:01:13 AM »
First check that the cable outers are fully home in the housing ferrules. If they are and no more slack can be created by seating them properly then cut 5mm off both the cable outers (old) which will allow the cable adjusters 5mm more movement, which should allow you to use them to adjust the cable tensions.

It would seem that you are correct, in that the cable adjuster mounts have been mounted closer to the axle than is ideal but you should be able to overcome that by shortening the cable outers slightly. Try 5mm shorter and see how it goes.

Best of luck, hopefully that will sort it. 

edit:
You should disconnect at the bayonets then pull one hub cable to full extension and measure the length then repeat on the other hub cable, pull to full extension and measure the length.  Both hub cables (1 & 14) should be equal lengths when measured at their full extension (165mm), otherwise it has been fitted incorrectly.
« Last Edit: August 13, 2019, 04:52:04 PM by macspud »

slogfester

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Re: Gears and cable changes
« Reply #6 on: August 13, 2019, 09:15:39 AM »
Thanks for quick reply macspud.
I will triple check the cable outers and ferrules.
Originally, when the cable pulley groove was set to the 10 oclock position on the shifting shaft, gear 1 hub cable was about 172 mm long fully extended. Hence the problem with it running in to the barrel adjuster. By now mounting it at c. 8 o'clock, both hub cables are c. 165 mm fully extended and roughly equal length. See pic 3 attached of gear 14 hub cable fully extended and compare with pic 1 above (of gear 1 hub cable fully extended). I'm guessing that they will never be exactly equal length because of the slight variation in the angle they exit the hub?
I lay awake last night wondering if I should shorten the shifter outer and/or lengthen the inner?  :-\ Thanks for clarrifying. I guess I can TEST this on the old outer+inner IF I can undo the female bayonets without destroying the cable ends.
« Last Edit: August 13, 2019, 09:18:48 AM by slogfester »

slogfester

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Re: Gears and cable changes
« Reply #7 on: August 25, 2019, 04:02:02 PM »
I finally got chance to work on this. Managed to unscrew the female bayonets after soaking them for 24 hours in WD40, but as other have reported, the end of the shifter cables had 'welded' themselves to the bayonet so they frayed when I detached them, necessitating a messy 2 mm prune of the inners inorder to re-thread them.  I was able to cut c. 10 mm off both shifter outer cables, wind the barrels back c. 8mm , and re-thread the inners. Result- see pic :) Of course, having butchered the inners, its now very sticky, so  I now HAVE to renew them and the outers. But I'm still left with the feeling that along with shortening the new outers 10 mm, I should add a couple of mm to the inners as its still all pretty tight when connecting the bayonets?

macspud

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Re: Gears and cable changes
« Reply #8 on: August 26, 2019, 04:56:31 AM »
But I'm still left with the feeling that along with shortening the new outers 10 mm, I should add a couple of mm to the inners as its still all pretty tight when connecting the bayonets?

By shortening the outer you are in effect lengthening the inner. Try winding the adjusters in a bit.
You have taken 10mm off the outers but by cutting 2mm off the inners and winding out the adjusters 8mm you are back to the original tension. By winding the adjusters in you can create some slack in the cables.
I hope this helps. Keep tinkering, you'll get there.   

PH

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Re: Gears and cable changes
« Reply #9 on: August 26, 2019, 10:10:50 AM »
its still all pretty tight when connecting the bayonets?
This is the one downside to the internal shift, in all other respects I prefer it to the external.
Couple of ways to make it easier - as I think macspud is suggesting, wind the adjusters in before you disconnect/reconnect to give you the maximum slack.
Also replace at least one grub screw with a cap head, this gives a far better grip.

I read of someone (I thought it was on here but can't find it) who had arthritic hands and problems with the connectors, they added an inline cable adjuster which gave enough slack to deal with it.

macspud

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Re: Gears and cable changes
« Reply #10 on: August 27, 2019, 04:51:12 PM »
its still all pretty tight when connecting the bayonets?
Couple of ways to make it easier - as I think macspud is suggesting, wind the adjusters in before you disconnect/reconnect to give you the maximum slack.

Well that and also to get the proper Rohloff prescribed working tension.