Basic Internal Hub Maintenance...
 

Alright, so I've got an internal Hub on my folding bike (Raleigh City 100) and also on my Mission Bike (local maker in SF).

Anyway, very few problems over the past year but both are starting to skip once in a while. Seems to be getting more common. The little white indicators are lining up just fine (not sure what the proper name is for that). So....

1) Should I be greasing the chain regularly on these bikes like a regular hub?
2) Might the chain just be getting a little stretched?
3) Should I be doing any other basic maintenance to keep these babies running smoothly?

Thanks!

The fix has to be appropriate to the actual problem. If the chain is skipping on the sprocket -- which is very rare, and nearly impossible when it's a closed loop (no idler arm) -- then deal with the chain.

OTOH if the skipping is internal to the hub (not chain related) then you have to put your attention there..

As I said, it's nearly impossible for a simple loop (2 sprockets, no idler arm) to skip unless the chain is very slack.

As always, more info would be helpful.It's hard enough to diagnose over the internet without knowing important details such as the brand, model and age of the hub. Just as an example, if you have a recent Shimano Nexus or Alfine 8 speed, some skipping in fourth gear is quite common. It's caused by one of the sun gears skipping over the shift pawl. This is one of the conditions that oil lubrication can help to alleviate.
Other makes and models of hubs have different internal actuating mechanisms, but adequate and proper lubrication, along with precise shift cable adjustment and free running, non binding cables will most often correct these issues.

Generalization maybe, ..but I've been using older nexus 7 and 4 speed IGH's forever with not any hint of problems --and no maintenance ever done (on the hubs). I keep hearing about problems on the newer alfines, so I am avoiding newer IGH's from shimano these days.

Right thanks. Yeah the skipping is definitely internal. I'll take a closer look and provide the model (I think it's nexus 7) but main question is really - does an internal hub ever require grease? are there reasons why a hub might skip on occasion? Also, by "skip" I mean sometimes when I'm pedaling the hub fails to engage and I pedal a revolution or two with nothing catching. Usually happens when starting from a complete stop.

No, IGH hubs should never be greased, except possibly for the main weight bearings. A decent sticky oil is what's best, so the hub can "splash" lube as the wheel turns at low speed. Some people and hub makers recommend grease for the two outer axle bearings which carry the load, others say the oil is adequate.

If you grease the internals you can cause the lightly sprung pawls not no properly engage properly, which can cause skipping, or total slippage, and/or can cause chipping og the tips of the pawls or ratchet ring.

FWIW - I grease the axle bearings, and keep little enough oil inside that it doesn't weep out and dissolve the grease. Friends are OIl only, and between us we can't see that one method is better or worse.

The painted lines are sometimes baseline suggestion for getting you in the correct-sh range, rather than accurate, precise indicators of where perfect tune happens.

From where the lines indicate the hub should be in tune, try backing off the cable adjuster a couple 1/4 turns and see if that makes a difference. Worse? Go back a couple 1/4 turns to where you started and keep going another couple quarter turns the other way. Check again.

Might not fix the issue, but since it is as simple as it gets before delving further, worth part of your diagnostics routine...

How long have each of these hubs been in service? Over a year, and I'd definitely advocate lubing with a heavy oil.

Apologies in advance for hijacking this thread but since we are on topic.

I have a similar problem on my 3 speed Shimano Nexus hub. It has been about one year in service. Around 1500km. The third gear skips very badly despite the markers lining up. I've tried adjusting it back and forth but it looks like pretty bad. I'm considering opening it up and attempting maintenance myself. Is it a difficult job to service the hub? Are basic tools sufficient? Are there instructions out there I can follow?

Getting the LBS to do a service is too expensive, and it seems to me that purchasing a new hub is the way to go for me.

I also have a Nexus 7 hub on a second hand bike - not very much used. The 4th gear has the symptoms you say - slight skipping. May I ask how the oil lubrication you describe can be done?

Problem is that the hub is built into a wheel, so a new hub means a new wheel (or rebuilding the wheel onto the hub). This isn't a cheap option, and IMO would be totally unacceptable for 1500km. One other possible option is a transfer of the entire internal assembly from a new hub into your shell. But this is similar labor to opening and checking your hub.

Lastly you might see if you can find someone with the same hub in a trashed wheel. If he also opted to replace rather than rebuild, he can sell you his used hub and you can do an internals swap.

If you're mechanically inclined, consider watching one of Dan B's hub rebuild videos, and seeing if you can open, clean and relube the hub and if that solves the problem.

Here's a video showing the removal of the internals from a Shimano Alfine 8 speed, and the oil dunking procedure. Removing the internals from a 7 speed is similar, except the drive side dust cap is not screwed on.
Also, depending on the age of the hub, removing the gear carrier from the axle can be tricky. Actually, it's not the removal so much as the re-installation. Newer models are not a problem as they come off in one piece, but older designs come off in two sections and care must be taken to get them back together correctly. Sorry I can't be more specific about that, but it's been quite a while since I've been inside a seven speed.
Note in the video, I use ATF for the oil dunk. I don't endorse it as a lube, but I am running a long term test on this hub and doing annual service on it. It now has about 13,000 km on it and coming due for it's next service.

Thanks for the advice. The reason I am considering replacing the hub is that a different LBS (not a very sophisticated place though) rebuilt a wheel for me very cheaply ($16USD) by using a replacement hub of the same size and no. of holes. The original spokes were used so there was no need to buy new. I felt that the same could possibly be done if I repurchase the same model of this 3 speed hub.

Given the severity of the problem, is it possible that the hub internals are damaged beyond repair, necessitating replacement parts? Are replacement parts easily found?

I'll have a look at some of Dan B's videos. Thanks for the suggestion.

Thanks for this. I can't watch the video now since I'm at work. I'll take a look later tonight.

Historically I've used grease for bottom bracket bearings, cup-cone bearings and the like, and sewing machine lubricant for the chain. So my understanding of lubricants is very small.

I'm guessing neither of these are suitable for gear hub interiors. What kind of lubes should I be looking for?

The hub I'm using is a SG-7R46 (Nexus 7) which I understand is an older model. The problem is very mild and I will try tweaking the cable tension first. But can you comment on how often you think this hub must be serviced? Are replacement parts necessary and if so, expensive?

FWIW, the Shimano Nexus 3, Nexus 5, Nexus 7, Nexus 8 and Alfine 8 hubs, the SRAM Automatix, iMotion 3, DD3 and G8 hubs, and the Sturmey-Archer 2, 3, 5 and 8 speed hubs and gearboxes all come from the factory with grease lubrication throughout. I'm pretty sure current production Falcon and MBI IGHs use grease lubrication as well. IIRC Sturmey has been greasing new production hubs since ~1984, SRAM since ~1976 and Shimano since before that.

Problems with re-greasing arise when people use a stiff wheel bearing grease in the delicate internal mechanisms rather than the light viscosity semi fluid greases formulated for it.
I'm a believer in oil lubing the internals for most applications, but I just finished rebuilding a ball lock type SA 5 speed using Shimano Nexus grease, which is a semi fluid lube for the internals. Seems to work very well.

+1 Most people use overly thick greases, and/or greases that can thicken considerably when cold (warning to winter riders). There's a gray zone between thick film forming oils and light greases (though the chemistry may be different) and the factory grease is at or in that range. So a thick, sticky oil like Phil's, Chain-L or automotive gear oil will give the benefits of grease with less risk of excess viscosity.

If you prefer a grease, something like Lubriplate 630aa (note the double A) is a very high quality low viscosity grease.

For unknown reasons, folks are always trying to find 'what else' they can lubricate an IGH with.

Current 'factory manual' manufacturer's specified IGH greases:

Shimano: gear and bearing, Shimano part number Y-041 20600

SRAM: gear, SRAM part number 0369 135 200 – 200gm container
gear, 0369 135 201 – 35gm container
bearing, 0369.001.015
pinions, "quality cycle oil"

Sturmey: gear, Sturmey part number SA103A
bearing, SA103B

Alone among the IGH manufacturers, SunRace Sturmey-Archer has published in various official documents exactly what their factory lubricants are and suggested commercial equivalents. Their SA103A gear grease is an NLGI #00 and suggested Castrol Impervia TR Light as a commercial equivalent. Many American lawnmower repair shops carry NLGI #00 in 4 oz tubes as Snapper 7061017 or Stens 770-123. Sturmey says their SA103B bearing grease is an NLGI #2 and one commercial equivalent is Castrol LMX. A commonly available and useful NLGI#2 grease is Sta Lube blue Marine Grease.


Note: Lubriplate 630aa is an NLGI #1 grease, simultaneously lighter than Sturmey specifies for bearings and heavier than Sturmey specifies for the internal mechanism.

Actually, I think that's the latest, current production version of the Nexus 7 Roller Brake.

Quote:

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Are replacement parts necessary and if so, expensive?

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It's a Shimano hub, so not really. Shimano doesn't do internal mechanism spares. In the unfortunate case where you have a broken internal part in a Shimano IGH, you 1) buy a complete new internal assembly, possibly in the form of a new hub, swap the whole thing out and pitch the old one 2) scrounge another broken hub and see if you can recover the part you need from it, or 3) replace it with a hub from a manufacturer that provides support and spares. (Credit where credit is due: that would be Sturmey-Archer.)

Mea culpa. The contrarian in me says you don't have to paint cleanly inside the lines all the time.

Possibly for the same reasons folks insist on doing so with chains. (sorry, I simply couldn't resist the setup)..

Thank you for researching the specific info, but among the reasons folks may want to use alternative products are availability, cost, and convenience. I've been oiling IGH hubs for eons (since that was the specified lube of choice for SA (UK) hubs) and continue to do so because oil allows me to add lubricant and lubricate all internal surfaces without complete disassembly.

The factories may use a grease, and may specify grease, but they lubricate hub parts prior to assembly. Oil is easier to apply with reliance, and high film strength oil has proven itself up to the task.

Thanks for the info. I made some adjustments on the Nexus 7 last night and it seemed to be holding up now, though a bit precarious on the lower gears. Will do more fine tuning before making the decision to open up.

I always thought the 8 speed was the replacement. Guess I was mistaken.

The Nexus 7 is so wildly popular worldwide that Shimano had trouble filling OEM orders over the last couple of years. In several iterations and updates, it's been on the market for over twenty years - longer than any other current production hub design except the Sturmey-Archer AWC.