ElCani wrote: Also, running without the motor connected made no difference when it was recently slipping badly in sixth (pre-jiggle).
one possible (probable) reason for this was that the shift servo was wrongly positioned before the thing was disconnected. Unfortunately there is no way of knowing that the servo is correctly positioning the shift control or not; it is a stupid design from that standpoint.
It is bad enough with a mechanical hub; all you can do is to check the adjustment in fourth gear and then infer (by whether not the cable seems draggy or not etc) whether the other gears are correctly selected or not. It would be useful if the cassette joint had a mark for every gear not just fourth. With the Di2 version you know absolutely nothing about the accuracy of the servo movement. Duh.
If the potentiometer in the servo unit goes bad then the servo could do anything.
Glad it is working; not sure I believe it will be a long-standing arrangement though....
So your money would still be on the Di2? Even though I’ve had the motor unit on and off at least fifteen times (for cleaning, sprocket changing and general fiddling) since 2015, with no apparent effect on the slipping? Isn’t it more likely that a pawl in the hub was somehow dodgy and my jiggling has reseated it?
as I noted upthread, if that pawl was in some way faulty, the hub would slip in second gear as well as sixth. The pawl sees higher loads in second gear than in sixth, so is more likely to slip.
The Di2 servo unit contains a potentiometer which has to behave perfectly in order for the gears to be accurately selected; on a bike that sees any weather, the chances of this behaving properly are about the same as those of the volume control of a radio not going crackly if you keep it in the bathroom. They go wrong all the time; typically the pot has a carbon track and where this is most used it will also be most worn; there will be debris built up and this (plus the wear itself) tends to make the pot go intermittent. The wiper arm on the pot may have a precious metal tip but even this can become slightly oxidised/contaminated and (esp following a period of inactivity) may behave in an erratic fashion.
So yes, my money is on the servo. IME if such a potentiometer goes bad, it will show its true colours if you test it using about half the usual voltage; thus pots that are going bad can test (very) badly on a multimeter but still just about work OK when the service voltage is applied. For my sins I have plenty of experience with this; similar technology is used inside early 'Motronic' (gasoline engine management) air flow meters; they at least get dried out every time the thing is used, and the potentiometer itself is properly engineered. However they eventually go faulty too, with predictable consequences.
I've been reading this with interest and I'm sorry to hear that in the past you've had problems with your Alfine hub. However going by the correspondence between you and Brucey above it seems as if you've got things fixed now with your hub running better than ever and so fingers crossed your hub continues to behave itself!
In terms of my experience with the standard non-Di2 Alfine hub I thought that I had made progress and got somewhere back in November and at first the hub seemed alright on a slow & short test ride when I'd reassembled everything.
However pretty much as soon as I resumed commuting with the bike the hub returned to its previous ways of slipping out of almost all of the gears. I double checked things such as the making sure that the yellow lines on the hub were lined up which they were.
I noted that your problems included the hub slipping in 6th gear. On my hub 6th gear is the only gear that the bike will actually stay in without slipping. I can do my entire commute in 6th gear without the hub slipping and so this is pretty much what I've have done since November. So I essentially ride a single speed bike albeit that the rear hub is an Alfine IGH.
If I do try to use the gears it might stay in 8th for a little bit if I'm really lucky but not for long. If I try to use 7th it will slip out of gear almost instantly. Gears 1 to 5 aren't much use at all because it will slip out of all of them. It's only when on the commute that I'm tired or it's really windy and perhaps going up an incline that I'll try to use gears 1-5 because you end up almost having to make slight adjustments by friction shifting as you go along to try and keep it in gear.
All of this is incredibly frustrating and I've had numerous moments where I've felt like impersonating Basil Fawlty in Fawlty Towers when he gives his Austin car a damn good thrashing! This has been on days when I've really wanted to use a gear other than 6th but the hub has resolutely refused to stay in any gear apart from 6th leaving me wanting to abandon the bike right there and never use it ever again.
I really want to like the Alfine hub because I love the idea of having an IGH on my commuting bike because I think that in theory it makes a lot of sense for many reasons. However the actual experience that I've had with this bike whereby since I've had it from 2014 the IGH has spent the vast majority of time unusable through its full gear range has left me exacerbated with the situation.
I'm very close to one of either two things. One being to buy a single speed rear wheel for my bike and just run the bike as a single speed. However I'm not as young as I used to be and I'm not sure that my knees would be very happy with a single speed 100% of the time and so I may go back to commuting on a bike with derailleur gears.
My apologies because this doesn't offer you any advice or help but you've had lots of advice from Brucey and fortunately you seem to have solved your problems.
I hope that your Alfine hub continues to behave itself!
Hi John. What I’ve learnt from reading many hub gear threads and posts (mainly Brucey’s!) on here is that the majority of faults are caused by the external parts of the system (cable, cassette joint, shifter etc). The quality of the cable installation appears to be particularly critical.
Have you been through a systematic trouble-shooting process with your bike? If not, I suggest you search the forum for the various threads on Alfine and Nexus hub gears and use the info in them to try and narrow things down. It will probably take a while to read through them, but hopefully you can find a resolution.
If it helps you feel better, as soon my Alfine 8 was working well I immediately turned a fully-functioning Nexus 7 hub on another bike into probable-scrap, through pure careless stupidity!
ElCani wrote: My Landrover swivel SFG has arrived, but I'll let sleeping dogs lie for now and keep running it with EP-90, none of which has come out.
So... after five months and roughly 1200km of pretty much faultless operation, I decided to wake up the dogs. I've had the swivel SFG sitting around and with the onset of winter I wanted to put it in the hub. I selected gear 1, dismantled everything and this time was able to separate the axle unit from the rest of the hub internal. After adding the SFG and putting everything back together... the slipping was back. B*gger. Worst in gear 7, but also present in 6. No slipping in 5. I didn't bother to test other gears.
Tonight I had it apart again in order to attach the Di2 motor unit to the axle assembly and see if I could spot anything wrong. All the pawls seemed (to my untrained eye) to lift and retract ok, but I did notice that the noise made by the motor unit on upshifts was inconsistent, very often 'jittering' just after the shift is made. I don't know if this is normal behaviour, but it was definitely not the same with every shift (into the same gear). Below is a video showing what happens. I am repeatedly shifting from 5-6 (hub starts in gear 5) and back again, until the point where I say "going into gear 7" after which there are some 6-7-and-back shifts. There is in fact only one 5-6 shift (the fourth one) that doesn't have a "jitter" after the shift. If anyone (Brucey ) knows whether those shifts look/sound normal or if they are evidence of a problem with the motor unit, I'd love to hear from them.
I took it for a brief test after putting it back together and there were no slips, but we shall see what tomorrow brings.
FWIW I have had the motor unit off and on a couple of times over the summer, with no ill effects.
if (when tested on a bare axle) the servo motor doesn't 'settle' in one place immediately suggests that there is a fault related to the shift control. Specifically that either
a) on test, when there is no load for the servo to fight against, the motor tends to overshoot the correct position and then has to reverse slightly to get to the correct position before it settles or
b) that the 'resolving' potentiometer inside the servo unit (the one that tells the servo where it is) is faulty
Ok, thanks. The settling also occurs when the hub is complete and installed in the bike, but I haven’t checked for it while pedalling. I will try it on the stand and take it from there.
Definitely does the settling when pedalling on the stand. Haven't been able to ride it properly yet, but unless the 'magic' fix that happened earlier in the year has happened again, I'll buy a new motor unit.
a thought; if the servo unit has water in it and you work on the bike upside down, the resolving potentiometer could be getting damp whenever you work on the bike.
It may be possible to disassemble the servo (it is on cybernexus units); if so, you may be able to at least find out what might be wrong if not actually fix it.
The bike is never upside down, but it sees a lot of weather. What’s odd is that just disconnecting and reconnecting, or removing and refitting the motor unit, has never resulted in a change of behaviour (good or bad). Only disassembly and reassembly of the hub internal has done that.
It didn’t slip today, so I’m hopeful that last night’s reassembly was a lucky one, but I will investigate taking the motor unit apart.
Just to update this, the system has been running faultlessly since my last post. I also tested another working 8 speed Alfine Di2 system at work and the motor unit showed the same “settling” behaviour as mine.
Hi All, absolute brilliant knowledge on this thread, I’ve recently downgraded by Di2 alfine, as my commute has changed from a 10miler, to a 4Miler including 80 steps (when the lift is not working/ it never is), and no secure bike parking. So I’m on a £100 single speed now.
I missed the gears for a few of the short knockabouts with my son, (plus I love messing around with bikes), so I brought and ‘old’ alfine 8 VSF off EBay for £50, which wasn’t working, with the hope I could fix it @£50 not much to lose. It’s in really good shape, I think hardly used. Brakes were just a bleed, and it has a great set of hydraulics discs now, Dynamo fixed. Seat post has also been released... and actually cleaning up the bike I don’t think it’s done many miles at all... but the hub/drive chain were not working at all. first there was a few obvious things. I indentified thanks to this thread.
1 - it had a SA 1/8 cog and a 9 speed chain. 2. Inner cable was kinked and rusty. 3. Inner cable was not sat in shifter correctly. 4. Shifter indexing corrected.
At this point it was now rideable. Quite a few of the gears did engage and it didn’t slip. The lower ones didn’t really offer much, but the grinding in all was immense..
So I took the hub apart, this is really into the unknown for me.. .. the large ball bearing ring on the driveside is a mess, bent out of shape, ball bearings loose in hub and 3 missing completely. I suspect someone had tried to removed this by pulling it over the drive side.
Second, on the non-drive side there is two sort of bearing hubs with longer type bearings (not sure what they would be called, but they are more the shape of chain pins). There is a small ring and a large one. Small one nearest the brake is in good shape, the large one (which I’ve not yet worked out how to remove) is most certainly not, many of the pins are not present even in the hub (just the holes where they used to be) and some of the housing is broken/rusted away. Unsure why this seems to be metal, and the smaller housed in plastic.
I’m on the verge of righting the hub off. I’ll try and upload some photos if I can work out how, but anyone know if/where you can buy these parts, and if it’s even possible to change the larger one with the ‘Bearing pins’? If they can be purchased?
) knows whether those shifts look/sound normal or if they are evidence of a problem with the motor unit, I'd love to hear from them.