Problem with internal cabling to hub gears

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vandjq
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Problem with internal cabling to hub gears

Postby vandjq » 3 Apr 2018, 11:58pm

I bought a Cube Travel Pro in June 2016. I chose it because it was fully equipped for commuting with big tyres, hub dynamo lights and a rack to carry my panniers. And a Shimano Nexus 8 internal gear hub which is supposed to require very little maintenance :roll: All for £700. But it weighs over 16kg and shakes my teeth out when I go over uneven road surfaces, even though the tyres are 47mm wide with low pressures. Ever since I bought it I've had bother with the gears slipping, mainly in 4th. Brucey convinced me that the hub is OK and it's the cable causing the problem. So I took it back to the shop, who sent the wheel to Shimano, who said the hub was OK. I've changed the cable three times without success. And installed the waterproof version of the cassette joint. The third time I lubricated the cable with Finish Line grease with Teflon as recommended by Brucey. But the bike has internal cabling in the down tube so I have to cut the housing twice. The yellow marks line up when I shift from 1st gear to 4th, but not when I shift from 5th to 4th. And it still slips in 4th. To be honest I'm getting a bit sick of this bike. It's in the shed and I'm using my derailleur bike to commute, which only weighs 13kg. That one sails over the bumps. But before giving up on the Cube, I thought I'd ask for some opinions:

a) Is it possible/economical to get hold of a lighter frame with external cabling?
b) Will improving the cable run get rid of the problem with slipping gears by keeping the cable covered by housing/grease for its full length?
c) Would it help to swap the RevoShift gear changer for a Rapidfire set-up, which might be more precise?

Any advice would be most welcome. Surely there must be lots of people out there who are running hub gears without all this bother?
Last edited by Graham on 4 Apr 2018, 5:12pm, edited 2 times in total.
Reason: Title

firedfromthecircus
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Re: Say goodbye to hub gears?

Postby firedfromthecircus » 4 Apr 2018, 7:58am

First thing I would try is an external cable run clipped to the frame with cable ties. If the indicator won't return to the mark after changing down then it almost certainly is an issue with cable friction, probably caused by the internal cable run. Fit an external cable, and if it works properly then you can decide whether to live with an (unsightly?) external cable or prepare for a fight with the retailer/manufacturer for a frame replacement as your one is clearly not right.

pwa
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Re: Say goodbye to hub gears?

Postby pwa » 4 Apr 2018, 8:15am

Maybe it should be "Say goodbye to internal cables".

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squeaker
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Re: Say goodbye to hub gears?

Postby squeaker » 4 Apr 2018, 10:01am

vandjq wrote:I bought a Cube Travel Pro in June 2016. ....But it weighs over 16kg and shakes my teeth out when I go over uneven road surfaces, even though the tyres are 47mm wide with low pressures.
47mm or 57mm (as per this spec sheet)?
The spec sheet shows heavy MTB tyres :roll: What pressures are you running them at? Swapping to a decent 40mm road tyre at sensible pressures would make a significant difference to the feel of the bike.
"42"

reohn2
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Re: Say goodbye to hub gears?

Postby reohn2 » 4 Apr 2018, 11:55am

Vandiq
Before doing anything else I would definitely try to prove the cable and revo shifter via an external outer casing and new stainless steel inner wire.
But before ziptying it to the frame I'd grease the new cables by squirting aerosol semi fluid grease(Carlude 100+ is ideal) down the outer and greasing the inner with Teflon grease,I'd also flood the internals of the Revo shifter with GT85 to clean it then follow up with the semi fluid grease to lube it.
I'd then install the new inner and outer cables in the Revo but not to the hub,you can now,by operating the Revo check it's working as it should by keeping some tension on the inner wire.
If all's well connect upto to the hub and zip tie to the frame(it should be quite a neat job if the rear brake cable is external like the 2017 model as you can zip tie the gear cable to the rear brake cable and there are brazons on the right side chainstay)

You don't say exactly what make and model of tyre is fitted or what pressures you're running them at,in the spec sheet on Cuba's site it says Shwalbe Smart Sam Activ 29er x 2.25inch,which are dedicated offroad tyre and won't be to good on tarmac especially if overinflated.
I'd recommend Big Apples 29er x 2.25inch run at around 25psi Front and 35psi rear for tarmac riding and light off road use.

Hope this is of some help
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mjr
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Re: Say goodbye to hub gears?

Postby mjr » 4 Apr 2018, 12:17pm

vandjq wrote:But before giving up on the Cube, I thought I'd ask for some opinions:

a) Is it possible/economical to get hold of a lighter frame with external cabling?
b) Will improving the cable run get rid of the problem with slipping gears by keeping the cable covered by housing/grease for its full length?
c) Would it help to swap the RevoShift gear changer for a Rapidfire set-up, which might be more precise?

Any advice would be most welcome. Surely there must be lots of people out there who are running hub gears without all this bother?

a) Definitely possible. Economical depends on the value you put on it.
b) I'd expect it to improve it but it's difficult to know if it'll get rid of the problem without knowing for sure if it's the cable causing it. I feel it's a relatively cheap test worth trying.
c) I doubt the Rapidfire would be more precise, as I understand it, but I could be wrong.

There must be lots of people out there who have the Cube Travel Pro. I'd expect forums to be awash with grumbles (maybe mainly in German) if this was a widespread problem.

I've run two hub gears without bother and one with, but they've all been three speed which probably need less precise adjustment to avoid slipping. The bothersome one was a Shimano but it was minor bother: sprocket slop and driver wear probably due to backpedal braking and adjustment fun because all the stuff on the axle meant the bell crank was slightly further out on the axle than Shimano spec, meaning I had to deliberately misalign the yellow bars for correct operation.
Vorpal wrote:
squeaker wrote:
vandjq wrote:I bought a Cube Travel Pro in June 2016. ....But it weighs over 16kg and shakes my teeth out when I go over uneven road surfaces, even though the tyres are 47mm wide with low pressures.
47mm or 57mm (as per this spec sheet)?
The spec sheet shows heavy MTB tyres :roll: What pressures are you running them at? Swapping to a decent 40mm road tyre at sensible pressures would make a significant difference to the feel of the bike.

Are you suggesting they put narrower tyres on it? I should think they would want to do the opposite?

"Schwalbe Smart Sam, Active, 29x2.25" " are on the spec, which are knobbly MTB tyres weighing 810g each "and even rolls well on roads" (say Schwalbe's website) - I suspect "decent" and "road" are more important for comfort than going narrower and "sensible pressures" more important than anything. When I ride tyres that wide, at I think about 30-40psi, I can barely feel the road. Narrower would normally be lighter and my usual compromise is 37mm tyres but I ride sprung saddles.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Brucey
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Re: Say goodbye to hub gears?

Postby Brucey » 4 Apr 2018, 4:49pm

you need to use the merest smear of Teflon grease on the cable (which MUST BE one with a nicely lined compressionless outer, well prepped (ie with ground ends to the housing, the correct ferrules fitted etc) and a polished stainless steel inner, not some random old rubbish) and you need to add some oil too if the cable housing run is long; the lube will possibly be too draggy otherwise.

If your revoshifter is in good shape it should work OK, but if the grip is not perfectly free to rotate for some reason (the rest of the grip can foul on it, for example, or it may just be binding internally) the shifting can be very poor.

Additionally if there is a fault (shifter, cable, cassette joint) such that the cable is not pulled firmly back on downshifts, you will get bad shifting. Some folk have fitted an extra spring to make their gears work properly; I would say that their cables are bad and that with good cables fitted this ought not be necessary.

There are hundreds of thousands of bikes fitted with N8 hubs and revoshifts which don't give this sort of trouble. Whatever fault you have I would expect someone reasonably competent to be able to fix it without too much difficulty. You may be frustrated but buying a new bike is something of an overreaction to this sort of problem.

cheers
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vandjq
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Re: Problem with internal cabling to hub gears

Postby vandjq » 4 Apr 2018, 9:23pm

fired from the circus - thanks for the suggestion to try external cabling

pwa - the moderator changed the title of my post - not sure why :)

squeaker - the original tyres were so large that they fouled the mudguards. A few people on the Chain Reaction Cycles website noted this problem; here are two:

' Thought specification good, should be trouble free with hub gears, dynamo, disc brakes etc, but should have taken more notice of weight, 15kg plus and 2.5" width tyres which are totally over the top. On delivery mudguards were troublesome fouling tyres, and 3rd gear slips.'

and

'...everything was more or less at expected level, but I expected much more quality on transmission, Nexus is not working at same level than other parts as brakes or wheels. Good tyres for mud and trails but too wide and heavy for commuting.'


I wish I had read these comments before I bought the bike. I replaced the tyres with the widest Schwalbe Marathon Plus I could find, i.e. 47-622, because avoiding punctures is the most important thing to me as it is very difficult to remove the wheel and change a tyre by the roadside. But I appreciate that they are probably even more heavy than the originals. Anything smaller looks silly because the frame is designed for large tyres. I run them at 45psi rear and 40psi front.

reohn2 - I will try your suggestions to operate the Revoshifter without connecting the hub and how to route the cable.

mjr - Where would I find a replacement frame at reasonable cost? And I'll try a few searches in German forums. I have a friend who speaks fluent German.

Brucey - I have followed your advice faithfully. The cable came with a brand new Revoshifter and the housing came with a new CJ-8S40 cassette joint unit, and has the metal ferrule at the hub end which you recommended in another post. I applied a small smear of Teflon grease. However the internal cabling on this bike cannot be lubricated as I have had to cut the housing before and after it enters the down tube. I am using a proper bike cable/housing cutter. My doubts about the bike are not only related to the gears slipping, but also the overall weight. But if I can fix the gears I will consider buying a lighter frame. Are they available second-hand?

Thank you all for your suggestions. I am so impressed by the efforts people go to in order to help others in this forum.
Last edited by vandjq on 4 Apr 2018, 11:00pm, edited 1 time in total.

Brucey
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Re: Problem with internal cabling to hub gears

Postby Brucey » 4 Apr 2018, 10:03pm

IME when you cut gear cable housing with cutters you sometimes leave a set of rather jaggy ends that, when fitted into some frames/ferrules, cause problems sooner or later. I try to grind the cut ends square, deburr the liner and pay great attention to the ferrule used. Even so the frame fittings can sometimes cause the cable to be draggy where it passes through cable stops.

The combination of the PTFE grease and the oil is a very good one; the grease/oil mix can be made just thick enough that the oil doesn't creep out of the cable under its own steam.

BTW I have also omitted to mention another possible cause of bad shifting; a deformed axle. The axle can get bent permanently (try rotating it and seeing if the ends swash at all) but this is unlikely. However, some frames have badly shaped and/or deformed dropouts such that when the track nuts are tightened, the axle is deformed (sprung) into a very slight curve, and (because it has a shift sleeve that rotates around the axle) the shifting mechanism then cannot work properly. The symptoms are similar to that of a draggy cable. To test for this, see if the static shifting (on downshift) is any different when the tracknuts are loose rather than tight. [NB esp on a belt drive bike, the axle can be similarly deformed by excessive belt/chain tension.]

Another possibility is that the cassette joint is draggy; this can be caused by dirt, or perhaps that one of the plastic washers is misplaced and is binding slightly.

In any event you ought to be able to check the cable run directly for dragginess; set the gear in top, then hold the cassette joint and move the shifter to low gear. Then let the cassette joint pull the cable through whilst (by hand) resisting this motion at the shifter end by holding the cable. If the spring isn't pulling the cable with great enthusiasm, you will be able to prevent it from moving with only modest force at the other end.

Regarding weight, adding such a hub to any bike adds about 2-3lbs vs a singlespeed setup. A good way of making a fast bike with an IGH is to start with a singlespeed bike, reset the frame to an OLN suitable for the hub you want to use, and have at it. If you start with a 19lb singlespeed bike you will end up with a 22-23lb IGH bike.

cheers
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John_S
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Re: Problem with internal cabling to hub gears

Postby John_S » 5 Apr 2018, 12:25pm

Hi vandjq,

I’m sorry to hear that you’re having problems with your IGH setup because it’s really frustrating when you’re bike is not working as you want it.

Now first off I’ll apologise because I can’t help by adding any technical knowhow or additional tips but you’ve got plenty of really knowledgeable people who have kindly offered lots of advice above.

However I can completely sympathise with your situation because I am in a similar situation myself. I have a 2014 Genesis Day One Alfine 8 and ever since I’ve had the bike I’ve returned again and again to shifting problems. I’ve had problems with the IGH in terms of gears slipping on a regular basis and problems selecting a gear in the first place. In its lifetime it has been to a couple of LBS and it’s had two new gear cables. The LBS have at times seemingly improved the issue, although not completely eradicated the slipping gears, but it’s always a problem that returns.

Now following lots of helpful advice on this forum my next move with my own bike is to try changing the gear cable and this time I’ve bought a Jagwire Universal Sport Gear cable which I’m hoping is going to help. At the moment I’ve just awaiting the arrival from a LBS of some new bar tape and mudguards because time & winter has taken its toll and my bar tape needs replacing and I have broken bits on both my front & rear mudguards which on this occasion can’t be fixed from my spares stockpile. Therefore once my new parts arrive I’m going to try and do everything at once including changing the gear cable. In the meantime I’m riding the bike as a single speed because for whatever reason 6th gear is the only one that it will stay in for a ride as every other gear slips.

Having read the advice on this forum what I’ve come to realise is that the gear cable and the fitting/positioning etc. is extremely important to having a well-functioning IGH. This got me wondering about a question which relates to your bike. From what I’ve seen there are a few of the Cube IGH bikes that come with a belt drive instead of a chain and I wondered if yours has a chain or a belt?

The reason that this popped into my head is because, if I’m getting this correct, a chain stretches over time. Now if I’ve understood this right my bike has horizontal dropouts in order to allow you to tension the chain as it stretches. But if the IGH is so sensitive to the positioning of the gear cable then even if you get your gear cable set up perfectly in the first place then each time you move the wheel/axle in the frame in the horizontal dropouts in order to tension the chain then this adjustment will also put out the gear cable position/indexing and so adjustments will be required whenever moving the wheel otherwise you’ll again suffer from a misaligned cable and problems with gear selection / slipping gears. At the same time this has got me thinking if on my bike which has disc brakes if the action of tensioning the chain by pulling the wheel backwards in the dropouts also causes the disc rotor to become misaligned in the caliper.

If this theory above is correct it’s why I wondered if you have a belt drive because I thought that belts shouldn’t stretch and so potentially make a good match up to a bike with an IGH. However maybe this thought is just absolute rubbish and nonsense given that IGH have been around on bikes for a long time now and have functioned perfectly well with chains over the years.

I wish you the best of luck getting your bike sorted because I do empathise with your frustration and not being able to get your IGH working properly because of the similar problems that I’ve had myself. It’s frustrating because I firmly believe that having a bike with an IGH is preferable to a derailleur geared bike for the type of riding that I do which is year round all weathers commuting. I really like having a single chain ring and sprocket because I think that makes life easier when cleaning the bike. I also have no problem with the number of gears or the range that I have which I think is fine for commuting.

However I do find the slipping gears & issues that I’ve had with getting it set up frustrating. I completely appreciate your frustration at the situation and I myself have considered that if my new gear cable does not help solve the problem of either (a) changing this bike to a single speed (which I’m not sure about because my knees appreciate being able to change gear on my commute) or (b) getting a new bike with a 1x derailleur drivetrain.

Best of luck getting your problems sorted!

John

Roadster
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Re: Problem with internal cabling to hub gears

Postby Roadster » 5 Apr 2018, 12:51pm

Altering the rear axle's position in the dropouts should make no difference to the gear cable adjustment. This is because the gear cable's housing is stopped at the cassette joint which is attached to and moves with the hub.
It's important to have a grasp of how the whole shifting system works before attempting maintenance, repairs or modifications, otherwise you can easily end up chasing problems around in circles.

John_S
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Re: Problem with internal cabling to hub gears

Postby John_S » 5 Apr 2018, 1:50pm

Hi Roadster,

Thanks for your message advising that the position of the rear axle in the dropouts should make no difference to the gear cable adjustment. I'm not technically minded by nature and so the tips and advice from people on here is a life saver.

Cheers,

John

Brucey
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Re: Problem with internal cabling to hub gears

Postby Brucey » 5 Apr 2018, 7:25pm

In theory it makes no difference if you move the wheel but in reality if the gear cable housing is not free to slide within its eyes or there is a cable stop in the wrong place then moving the rear wheel can result in a change in shifting precision/position, or one that is OK to start with but then moves eg when the handlebars turn fully and strain the gear cable differently.

There is also another factor concerning the cassette joint which also changes subtly with installation and wheel position. Normally the fixed part of the reaction arm is (on low normal hubs) pulled as far ACW as it will go (within its backlash on the splined fitting) by the spring tension in the hub's shift mechanism. However occasionally the cable routing is such that the reaction arm is pushed CW by the cable housing, yet can move around when the gears are shifted. This eventually wears the splined location of the reaction arm on the hub, and in the meantime results in imprecise/inconsistent shifting.

If you don't spot the reaction arm moving around, you might mistake the imprecision in the gear alignment to be due to a bad cable or something.

Worse yet if track nuts are not tight and/or the NTWs are not locating the hub axle properly, then the reaction torque causes the axle and CJ to flap back and forth a little depending on whether you are using a low gear or a high gear. The axle tries to turn ACW or CW (as viewed from the RHS) respectively. If the axle moves the CJ also moves and this can strain the gear cable and intermittently produce either of the two faults I mentioned above. This does not manifest itself on the workstand because the applied torque is not usually enough to cause the reaction torque to be high enough to turn the axle.

cheers
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Roadster
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Re: Problem with internal cabling to hub gears

Postby Roadster » 6 Apr 2018, 1:50am

Brucey wrote:In theory it makes no difference if you move the wheel but in reality if the gear cable housing is not free to slide within its eyes or there is a cable stop in the wrong place then moving the rear wheel can result in a change in shifting precision/position, or one that is OK to start with but then moves eg when the handlebars turn fully and strain the gear cable differently.

But in reality those are cable routing and cable length problems, not cable adjustment problems. Neither of those is changed in John's case, but only the wheel position.
Similarly, nor is the placement of a cable stop changed. There are only two cable stops which affect the cable adjustment, one at the shifter and the other at the cassette joint, so how can either of those be "in the wrong place"?

vandjq
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Re: Problem with internal cabling to hub gears

Postby vandjq » 7 Apr 2018, 12:42pm

John S,

Thank you for your sympathy but your problem is much more serious than mine. My hub slips occasionally in 4th but you're only able to ride in one gear. I'm not surprised you are thinking of giving up. On Roadster's advice I tried that Jagwire cable, but as Brucey says if you have a good quality cable and it still slips, the lubrication is probably more important. I've got a new Shimano cable ready to install. Also, here's a quote from Brucey:

NB with CJ-8S20 especially, it is absolutely imperative that you use the correct (metal) ferrule at the cassette joint end of the housing. The ferrule is supported on two small projections and plastic ones can just fail. The shimano cable (which comes with 8s shifters) has an aluminium ferrule that is crimped onto the cable housing. A loose metal ferrule will work but the cable housing can pop out the ferrule which throws the indexing off.]


I recently changed the Revoshifter on my bike and the new one came with a new cable and housing with the correct ferrule. But due to the internal cabling on my bike I had to cut the housing. I'm now going to follow the advice I have received earlier in this thread to route my cable/housing externally in a continuous run. But I will not be able to re-use the original housing as I have cut it. I doubt whether the housing is available separately from the shifter, but someone else may know better.

Regarding belt drive, I considered that two years ago but decided on a chain because the belt drive version was £200 more expensive and the belts are expensive to replace. But it is a lot lighter as the weight of this bike is a big drawback for me. I don't think I'd have much choice now as most of the new hub gear bikes seem to come with belts. You need a special type of frame for a belt, and I don't think it would solve your problem.

My hunch is that both our problems are caused by cables, but having said that the fact that your hub slips in so many gears does suggest an internal problem with the hub. But like you, I'm not very technically proficient and would not be confident enough to open up a hub. Here's another quote from Brucey:

There are hundreds of thousands of bikes fitted with N8 hubs and revoshifts which don't give this sort of trouble. Whatever fault you have I would expect someone reasonably competent to be able to fix it without too much difficulty. You may be frustrated but buying a new bike is something of an overreaction to this sort of problem.


The problem is in finding a decent bike shop. Last November I fell off my bike and bent the front rim and broke the brake lever and the gear shifter. I took the bike back to the shop I bought it from. I had a broken wrist so was not in a hurry. I went back after Christmas and was told that they were unable to source a replacement Revoshifter from their supplier until mid-February. On 27 Feb they rang me to say they still couldn't get it, so I went and collected the bike. The good news was that they had done a good job of re-building a new rim around my Shimano dynamo hub. The bad news was that they had fitted a silver brake lever in place of the original black one, and they had not set up the pads correctly.

It took me three days to order and receive a new Revoshifter from SJS Cycles in Somerset.

Needless to say I shall not be returning to that shop. Good luck with sorting out your problem.