Notes on lubrication for internal hub bicycle gears

[philepo]

Notes on lubrication for internal hub bicycle gears

You’ll have to google centi stokes (cSt) and centi poise (cP) and how to convert them! J.

Basically there are 2 issues looking at viscosity: 1 a lot of manufacturers state viscosity at 40 C or the use cP and cSt, which are different depending on density (i.e. water is 1 cP and 1 cSt because it has sp gravity of 1 at room temp). Its hard to find consistent measuring techniques for viscosity, e.g. temp, cP or cSt etc. For the engine oil viscosities I have aimed to read them off at 10 to 20 C, not 40 C as is standard. Also, remember that grease is thick due to thickeners, not because it is viscous per se. I mean you can have a thick grease that's made from a thin base oil... The grease is made to keep the base oil near the bearing, not to 'be thick oil', if you get me.

Anyway, my fascinating (!) story on hub gear lubrication:

The old Sturmey Archer (SA) literature used to suggest using a few drops of oil (via the oil port on the outside of the hub) every few weeks and they used to say SAE 20 or similar. Since the late 90s oil ports to top up the hub oil are no longer present and instead they are filled with a semi-fluid grease (grade #00) from new and the maintenance instructions basically say they are either maintenance free or that they need ‘repacking’ occasionally.
There are many web forums discussing oil vs grease and so on, and based on my research this is my interpretation of the evidence plus some of my own opinions based on technical facts.

• SA used to state adding a few drops of SAE20 every few weeks
• SAE20 has a viscosity of ~200 cP at normal running temperature (i.e. 10 to 20 C, not 40 C)
• SAE20 is hard to find but SAE 20W50 is a common car engine oil for older engines and is easy to find – note 20W is its weight when cold… which it will be in a hub
• SAE20 or 20W oil should ideally not have detergents in it as it is best for debris to fall out of suspension and not circulate. However, these detergents tend to be designed for hot engine oil in an engine so may play no role at room temperature
• Engine oil tends to have lots of nasty chemicals and metal compounds in it and is bad for the skin and smells unpleasant so if possible, find a non detergent oil
• Gear oil of SAE80 is equivalent in viscosity to SAE20 crank oil (the scales are different) and so this can be used, but again is has lots of nasty additives and really pongs!
• Popular cycle oil, e.g. Weldite TF2 has a rated viscosity of 20 cP (temp not stated but presumed to be lab temp @20 C). The ‘extreme wet’ version of this has viscosity of 62 cSt at 40 C… so maybe 100 cP at room temp perhaps?
• GT85 has viscosity or 11 cP (again, temp not stated but I’d presume lab temp of 20 C). This is 16 cSt after density converted.
• These oils may be ok for general tasks where the capillary action is desirable in order to reach bearing surfaces but is 10 to 20 times too low for hub gears (i.e. SAE20 oil recommended by 1950s SA was ~200 cp)
• Note that grease of grade #00 has a viscosity of ~500 cp, so 2 to 3 times the SAE20
• Note that the latest SA data sheet I could find for my own 5 speed sprinter hub stated that SAE30 oil should be used. I went to the local shop and bought 30 weight lawn mower engine oil
• I stripped the old grease out (it was sparkling with metal debris) thoroughly cleaned and rebuilt with a very generous application of SAE30 oil (also did cleaned and oiled the chain with this)
• I have zero leakage past grease lubed bearings (I honestly put in quite a lot) and it run like a beauty, no more slipping that used to plague it in 1st and 2nd gear
• For best adjustment either follow SA advice and line up red mark or, simply put in 1st gear and adjust chain to be just tight (no play)… or just play around, they are quite finicky compared to 3 speeds

My personal experience:

• Old bike stood for a long time or weathered + hub stiff = squirt in gt85 (take out indicator chain to the oil will go to the internals). This will loosen up the old dry grease
• This worked to stop some slipping, but really it needed a rebuild. Watch out though, online Youtubers make it look easy, and it is once you’ve done one, but not the first.
• Also, make sure you leave quite a lot bearing play in the drive side. Counter intuitive but very important! Download the sturmey rebuild instructions, there’s lots online.

The logic I think drove hub gear manufacturers including SA to change to grease was:

• Most people don’t oil the hubs regularly to they run dry and damaged: people will then blame us
• Most people don’t have SAE20 in their can and/or have no clue what SAE20 even means – this is not the 1950s when men were proper men! 😊
• So what’s worse? A combination of too thin oil and/or no oil in their hubs, or fill them with semi-fluid grease that will last a couple of decades…

Based on all that, my suggestions for grease filled hub gears are:

• Minimum: Squirt in oil through indicator chain hole to loosen them up
• Ideally: Rebuild, flush out grease, re lube using SAE20 or SAE30 oil (not cycle oil or squirty oil)

Hope you enjoyed that

 

[MichaelW2]

Shimano Nexus/Alfine come with grease for no maintenance and an oil dip kit for better performance in heavy use. Chips of metal can become suspended in the grease or oil, so changing removes these points of wear from your gears.
Online advice and experience is that Shimano transmission oil is roughly the same as automatic transmission fluid at 1/10 price. I use an ATF dip every year.
Alfine 11 has a convenient drain hole so disassembly is not required.

 

[SkipdiverJohn]

In my experience, SA 3-speed hubs are not too fussy about exactly what spec of oil is injected into them, so long as it isn't thick like molasses. I've put all sorts of oils into my gear hubs over the years - basically whatever is still in my squirty oil can from the last time I filled it up. Most likely it will be something like a 15W/40 multigrade detergent engine oil.

 

[the snail]

Yep, anything is better than nothing. The grease in Shimano hubs is a bit rubbish imo. If you leave it too long it dries out, you end up with no lube where it's needed, and before too long you have a can full of rust. Better al least to squirt some oil in there occasionally and let it leak out over time, it might take some of the swarf with it.

 

[rogerzilla]

I use GL4 75W90 synthetic gear oil, which doesn't go gummy and is designed for the job. GL4 smells fine (it's GL5 or "universal" oil that mings because of the sulphur and phosphorus-based EP additives).

I think SA went to grease because of the inevitable seepage that occurs with oil. The rear wheel of an oiled SA hub can be a bit of a mess, and this creates a grinding paste for rim brakes on modern alloy rims.

 

[philepo]

In my experience, SA 3-speed hubs are not too fussy about exactly what spec of oil is injected into them, so long as it isn't thick like molasses. I've put all sorts of oils into my gear hubs over the years - basically whatever is still in my squirty oil can from the last time I filled it up. Most likely it will be something like a 15W/40 multigrade detergent engine oil.

Like I say, SA recommend 20 or 30 weight. Am sure anything is better than nothing though but the thinner it is the more likely it will leak

 

[philepo]

I use GL4 75W90 synthetic gear oil, which doesn't go gummy and is designed for the job. GL4 smells fine (it's GL5 or "universal" oil that mings because of the sulphur and phosphorus-based EP additives).

I think SA went to grease because of the inevitable seepage that occurs with oil. The rear wheel of an oiled SA hub can be a bit of a mess, and this creates a grinding paste for rim brakes on modern alloy rims.

Sounds good, but 75W is a little on the thin side, more like 10w engine oil, so may be more inclined to run out

 

[philepo]

In my experience, SA 3-speed hubs are not too fussy about exactly what spec of oil is injected into them, so long as it isn't thick like molasses. I've put all sorts of oils into my gear hubs over the years - basically whatever is still in my squirty oil can from the last time I filled it up. Most likely it will be something like a 15W/40 multigrade detergent engine oil.

Yep, anything better than nothing. But the thinner it is the more likely it will run out and make a mess. SAE30 is SA recommended

 

[philepo]

Shimano Nexus/Alfine come with grease for no maintenance and an oil dip kit for better performance in heavy use. Chips of metal can become suspended in the grease or oil, so changing removes these points of wear from your gears.
Online advice and experience is that Shimano transmission oil is roughly the same as automatic transmission fluid at 1/10 price. I use an ATF dip every year.
Alfine 11 has a convenient drain hole so disassembly is not required.

I like the idea of a hole to add oil and a hole to drain... might add that one day!

 

[philepo]

I use GL4 75W90 synthetic gear oil, which doesn't go gummy and is designed for the job. GL4 smells fine (it's GL5 or "universal" oil that mings because of the sulphur and phosphorus-based EP additives).

I think SA went to grease because of the inevitable seepage that occurs with oil. The rear wheel of an oiled SA hub can be a bit of a mess, and this creates a grinding paste for rim brakes on modern alloy rims.

With respect (why does oil cause so much aggro ? lol) I think you are wrong.
Gear oil for car gearboxes has many additives suitable for them, but for a simple SA hub there may be additives that are bad for certain component materials.
The best oil is SAE20 or SAE30 with no additives as instructed by the manufacturer. But in absence of that, I'd suggest a simple cheap minimal additive oil of the correct grade.

 

[rogerzilla]

Traditional SA hubs only have steel in them, I think. The sort of components that get attacked by the wrong oil additives are phosphor-bronze or aluminium, maybe some plastics. Car gearboxes are far more fussy. Later AWs have a plastic spring cap but I've never known one crack.

The trouble with cheap single-grade oil (and 3-in-1) is that it goes gummy.

I'm not a fan of the greased ones. The oiled ones don't need opening up for decades with regular drops of oil. The greased ones are supposed to be serviced annually, which means a total stripdown. Virtually no shop will do the job for you so it's DIY or a specialist. And I defy anyone to take an SRF3 fully apart and reassemble it so it works properly. The NIG design uses a horrible pressed steel shroud for the driver pawls.

 

[philepo]

Traditional SA hubs only have steel in them, I think. The sort of components that get attacked by the wrong oil additives are phosphor-bronze or aluminium, maybe some plastics. Car gearboxes are far more fussy. Later AWs have a plastic spring cap but I've never known one crack.

The trouble with cheap single-grade oil (and 3-in-1) is that it goes gummy.

I'm not a fan of the greased ones. The oiled ones don't need opening up for decades with regular drops of oil. The greased ones are supposed to be serviced annually, which means a total stripdown. Virtually no shop will do the job for you so it's DIY or a specialist. And I defy anyone to take an SRF3 fully apart and reassemble it so it works properly. The NIG design uses a horrible pressed steel shroud for the driver pawls.

Yes, old hubs oiled regularly will go on without the need for a strip down, but looking at the speckles of metal in mine I think they may benefit.
Actually, that may be a good argument to use oil that's on the thin side, i.e. it seeps out as a kind of total loss system (bit messy though!)
I should have added: don't use 3 in 1 as it's too thin (though arguably better than nothing)
It's not true that non-additive oil goes gummy and complex gear oil doesn't. All oils and greases will go gummy over time if exposed to air.
SA didn't say that greased hubs needed to be stripped once a year. They were quite vague and just said when need. Even then they describe repacking rather than a full strip and clean...

 

[Drago]

In my experience, SA 3-speed hubs are not too fussy about exactly what spec of oil is injected into them, so long as it isn't thick like molasses. I've put all sorts of oils into my gear hubs over the years - basically whatever is still in my squirty oil can from the last time I filled it up. Most likely it will be something like a 15W/40 multigrade detergent engine oil.

Everyone used 3in1 for that purpose when I was a kid, and no one had any problems. The British built Sturmey jobs were hugely tolerant, just so long as they had something in there.

 

[SkipdiverJohn]

I use GL4 75W90 synthetic gear oil, which doesn't go gummy and is designed for the job. GL4 smells fine (it's GL5 or "universal" oil that mings because of the sulphur and phosphorus-based EP additives).

Using GL5 in a SA 3-speed AW hub wouldn't faze me. However I'm reluctant to put it in anything with phosphor bronze bushings, like an old Land Rover main gearbox.

 

[roley poley]

On the sachs three speed I used to run oil ,any oil, in the hole left by removing the indicator rod while it was left on its side ,twiddle more oil and repeat till the black gunge that poured out the other side looked much nicer .Later when I learned from ewechewb how to take one apart would soak the innards in a bowl of engine oil .No problems from a 2002 hub used 2-3 times a week till present day.I am a fan of the bean tins of mystery and all my bikes have them (+2 nexus 8)