IGH lubrication; a smoking gun.

[AM7]

The hub failed by slipping in the high gear

That's a bummer - I picked up a secondhand CS-RK3 some time back and when I finally got round to building into a wheel, found that it sporadically slips in high gear. I put it to one side with the aim of sorting it out at some point in the future. I hadn't realised that the individual small parts aren't available separately, but at least if it needs a new internal, it's an easy - albeit expensive - fix.

Where did you get the replacement internal unit from?

[Mick F]

SJS would be my first port of call.
If they haven't got one, they probably know a man who does.

[Brucey]

....Where did you get the replacement internal unit from?

Three places to try;

- Isons
- The Cycle Division
- SJS

first two are trade only, so order via your LBS (if they have an account with them).

cheers

[AM7]

Thanks. I always used to get Sturmey parts from Olbiketrader, but he doesn't appear to be trading any more

[le.voyageur]

There's a post on the Rohloff section of the Thorn forum about someone on crazyguyonabike who has paid to have Rohloff oil analysed.
Here's the Thorn link
http://thorncyclesforum.co.uk/index.php ... ic=12554.0
and the CGOAB link
https://www.crazyguyonabike.com/forum/b ... sted=0&v=M

I'm personally wary about this as I have no knowledge of this sort, e.g. the oil additives and potential damage.

Thought it might be of interest to others on here.

[hoogerbooger]

yes this one again.

On my Brompton SRAM the gearing assembly is coated in what could be a semi fluid grease ( not runny not gloopy), but the main hub bearings/cones use a thick standard looking grease.

I note the suggestion for good maintenance of removing the gear chain and feeding gear oil or semi fluid grease through the hollow spindle . Will this not feed out and mix with the bearing grease ? If yes why is this not a problem ?

[Brucey]

nearly all common SRAM hubs are not oiltight, so using oil inside them is not a very good idea; it just comes out of the hub and washes any grease in the ring bearing out with it, making a horrible mess. The small lip created by the screw-in ball ring in a lot of SA designs means that the hub will (unlike SRAM ones) retain enough oil to be useful in the meantime. Shimano Nexus hubs will also allow oil to leak out but will usually retain more SFG than a typical SRAM hub.

So (IMHO) with a SRAM hub your only good choices are

a) to occasionally add SFG (eg via the axle) and to put up with the mess that is generated after every shot of fresh lube or
b) to strip the hub down and to use a modest amount of grease/ SFG on the insides, and a thicker #2 grease in the bearings .

Since SRAM are not making geared hubs (or hub spares) any more I'd suggest that in the short term you collect some spares and do whatever maintenance is required to make sure that an existing SRAM hub isn't going to come to harm. In the medium/longer term I would suggest that you think about using something else instead.

cheers

[hoogerbooger]

As it's pretty straight forward undoing the left hand locknuts and removing the internals, option b) seems sensible ? I have a can of Molyslip spray which is SFG. So is it likely to be sufficient just to spray, in a limited unzealous fashion, into the gear assembly and spin the whole axle arrangement in hand a bit to try and distribute whilst its runny, then reassemble when
not too runny and ride it a bit changing gear to try to further distribute. or will this just not get to where its needed, or on bits it isn't ?
(I'm thinking that as much as I like taking things apart, they don't always go back together so easily)

(Yes the sealing seems limited to non-existent and I am now wondering how water hasn't got in. I guess not enough mileage and luck with the trips and weather. Anyway I have a small stock of spares and we'll see who dies first. If I out survive both the SA SRF5(w) & SRAM hubs..I'll see what SA are producing then. In the interim I'll be taking the more reliable SRAM touring and hoping it doesn't rain too much, rather than the SRF5(w) and wondering if the hub will destroy itself !- actually I'll probably just be enjoying myself looking at the views).

[Brucey]

I've not used the spray you have so I can't comment much except to say 1) that it is probably an expensive way to add lube to the hub (most of what is in the can is probably solvent) and 2) that the lube will be worse than useless until all the solvent has flashed off, and that this may take a long time if the lube is put on in a thick layer.

The purpose of doing anything to a hub internal is to

a) clean any wear debris out of the hub
b) if not a) then at least dilute it
c) if not only b) then perhaps add solid lubricants that mitigate the ongoing wearing effects of wear particles already in the lube
d) inspect the internal parts for wear or damage and replace as required (in some cases before problems arise)
e) adjust internal clearances in some cases
f) protect the hub internals from possible ongoing wear and corrosion
g) to coat any seals with a lubricating/water repelling layer of some kind

Some sprays will achieve some of these objectives but they are unlikely to be a substitute for all of them.

A problem with using a thicker grease to lubricate an IGH is that the lube isn't at all mobile inside the hub; thus wear debris remains concentrated in (say) the planet pinion bushings etc where it tends to create an 'avalanche' effect (ever-increasing wear). Should water get inside the hub, corrosion may be localised. By contrast in regular use, oil tends to circulate within the hub and this helps to avoid localised problems. Some SFGs can do something similar; their reduced mobility vs oil can be offset by the fact that the hub will normally safely retain more SFG than oil.

cheers

[alexnharvey]

In an oil or SFG lubed hub, how does the lubricant circulate, is it picked up at the bottom and then drains down through the mechanism as it rotates? I have often wondered if any hub internals are designed to aid the circulation, for example with 'scoops' or ribs to pick up some oil.

[Brucey]

most simple gearboxes (and some engines) use 'splash lubrication' to refresh the oil coating on parts. Oils vary in how long they take to drain off parts when standing; some IGHs eg Rohloffs are deemed to be 'OK' (for several hundred miles at least) provided the surfaces are simply oily inside, i,e, there is no sign of liquid oil sloshing about per se. IMHO this works best if the pinion bearings have rolling elements; most IGHs don't have this (only nexus 8s premium/red band, alfine 8s/11s and Rohloff do) so are likely to wear quickly if the lubricant isn't plentiful.

Gearbox oils often contain additives that help with 'stringing' or 'climb' characteristics; this means that in (say) a gear train, the oil is lifted and transferred to other parts far more rapidly than if the additive wasn't present. You don't need much of this to happen before the gearbox is adequately lubricated whilst in use, but if the oil drains off the parts too quickly, you might get a 'dry start' at times.

Some (not all) SFGs have a cunning characteristic; a few minutes after being worked, they are thick enough to hold their own weight (more or less) so cling well to all surfaces inside a hub, and aren't likely to leak out. However when being worked, they 'shear-thin' enough that they behave more or less like oil, i.e. the lubricant can climb, splash, and penetrate where it needs to go to, and will impose a lower parasitic drag on the hub internal (some of the losses are to do with the shearing of the lubricant itself; drag losses are lower with oil than grease, until the lubricant film is breached and there is metal to metal contact).

This means that a hub lubricated with this kind of SFG will enjoy many of the advantages of a hub that is lubricated with oil, but will have a far lower leak rate, and can sustain an increased fill too; this means longer service intervals and better protection for the parts too. Once some hubs are 'run in' I'd expect them to go for several years and/or a five figure mileage on a fill of the right SFG. This is only possible with oil lubrication if the sealing is 'perfect', and even then there won't be as much oil inside the hub, so any wear debris will be a greater part of the whole.

cheers

[LiveFree]

Brucey- I just recently joined this forum, after reading several of your posts about IGH's: I must say that your knowledge of bicycles and especially IGH's is remarkable. I have just recently come back to cycling, mainly in a bid to help my body to recover from a rather serious auto-immune disorder. I bought a Pashley Sovereign Roadster (more on that in another post!) partly due to its low maintenance nature. Overall I am happy with it, although I had some considerable problems with the Nexus hub shortly after delivery- again, more on this in another post. For now though, my question is related to the topic that your original post was all about- IGH lubrication. I can see very clearly that the shimano service plan of dunking the hub innards into some sort of (very expensive) gloop with the intention of 'refreshing' the grease that is in there is woefully insufficient: which is very frustrating, since as far as I can see the only part of the bicycle that I can't maintain myself is the Nexus 8 IGH: I currently have to be rather careful with my energy levels/physical exertion or else I can run into problems. For this reason, I would rather not get involved with removing the hub internals each year and having to dip it into something to, hopefully, lubricate it.
I can see a DIRE need for an oil port, as used to be found on the SA hubs that were a fixture of my youth, and with this in mind I am wondering if by good fortune you happen to live anywhere near to Gloucestershire? If so, I was wondering- if I paid you for your time- would you be willing to come and drill me a lube port on the hub? Failing this, would you happen to know of anyone else that is in this area that might be able to do this for me or can you think of another option? I also have a minor residual issue with the hub that I would like an expert to look at- I will post about this issue separately. Unfortunately, there is no-one in the small town I live in (by way of bike shops) that is up to the job- I know this from experience! Your guidance on this matter would be much appreciated.

Many thanks.

[Brucey]

unfortunately I am not local to Gloucs but if I'm headed that way I'll let you know. Maybe someone else has a suggestion of someone competent local to you?

cheers

[LiveFree]

Thanks for getting back to me Brucey, that's a shame that you're not local: but thank you for offering to get in touch if you're in this neck of the woods at any point- 'tis much appreciated Actually, the little medieval town that I live in is well worth a visit anyway- there's a beautiful Abbey here just up the road. As you said though, lets see if anyone else that is local comes forward with any help- it would be ideal for someone to look at in situ to deal with the other issue prior to installing the oil port.
I take it leaving the hub just with the shimano grease in for a few weeks/couple of months won't do any harm? I'm not planning on riding it in the wet for now anyway. If no-one else comes forward, would you be averse to me whipping the whole back wheel off the bike and couriering it to you? At least this would get the oil port sorted, if not the other issue- unless it lies within the hub itself, although I doubt that. I will post the other question on this forum somewhere where the answer might be of use to others as well, if that's OK with you, since it's not lubrication related.
Also, I should add that I am currently having to store the bike in my little cottage (not ideal I know-) this will probably be the case for at least a couple of years: is this likely to cause any problems, especially once the oil port is fitted- one way or t'other? It is never very warm in my little home (!) but in the winter with the central heating running, I guess it is quite dry. I can't see this causing any problems with the shimano grease, but I am wondering with the oil? Alas, I currently don't have a shed- so there's not much else I can do.
Finally, am I right in thinking that once the oil port is done- all that is then required is to drop some oil (which oil?) into it each month, and keep the adjustment indicators level, or is there anything else that needs to be done to keep the hub running smoothly?
Cheers

[Brucey]

the latest instalment in this sorry tale of bad lubrication; Alfine 8s SG-S501. The internal should look like this




but imagine most of the shiny bits being brown and rusty and you will have a good idea of the one I had in front of me.




The faults with it included:

1) every roller clutch needed stripping to its constituent parts and cleaning (de-rusting and de-clagging).
2) the hubshell needed cleaning (i.e. de-rusting on the drive bands and bearing surfaces)
3) the main ring bearing clip needed to be replaced
4) parts #16,18,19,20 were loose, and parts #16,18 remained loose even after #20 was tightened properly. A special part was made to accommodate the discrepancy in the fit of the parts
5) the cassette joint was a baggy fit on the hub
6) the shift control mechanism in the axle assy was faulty
7) the selector sleeve wouldn't turn freely
8 ) because of 7) the axle pawls wouldn't retract fully (which meant that the hub wouldn't come apart in the normal way; the first stage disassembly which normally takes 30s took about an hour.... )
9) several of the pinion roller bearings were seized solid; the pinions would only turn by virtue of the pinion pins spinning in their seatings (very bad)
10) during reassembly one of the roller clutches was worn enough that it would override its set position, meaning that the spring preload on it would be lost. It took about six goes (each with slight modifications) to reset it correctly. Each time, amongst other things, the planet gear assy had to come apart and the primary planet gears needed to be retimed.

In fact the only common fault that this hub didn't have is the one where the sliding clutch is mistimed vs the pawl lifts (which results slippage in gear 5 or gear 4 regardless of the adjustment).

I have some admiration combined with a profound dislike for the shift control mechanism in the axle assy. When the Nexus/Alfine 8 hubs were first introduced, shimano clearly expected folk to disassemble this part and overhaul it; they offered tools to help accomplish this. However they have not offered all small internal parts and they now only offer the axle assy complete (#8). Anyway, special tools or not, it is a pig of a job; there are several springs that need to be preloaded (which is both difficult and a little dangerous; if one of the springs springs back it usually stabs you in the finger gratuitously) and the parts look as if they will go together in several different ways, whereas in fact only one way -and one preload setting from many permutations- is correct. One of the parts looks as if it will work either way up but in fact one end is a very slightly different size to the other and you only discover it won't work late on in the assembly procedure. This little lot had to come apart about six times for various reasons. One of the worst aspects of the whole arrangement is that when the RH cone is removed, should it be tight, the shift control mechanism ends to come apart by itself; this can result in a lot of unnecessary work....

Speaking of unnecessary work, most of the hub's troubles were caused by bad lubrication; the original white grease makes the hub quite draggy and does not inhibit corrosion very well at all; once corrosion starts, the now slightly acidic conditions cause the grease to react and turn to something that closely resembles cheese. Needless to say it is not a very good lubricant.

By contrast if the hub is lubricated properly it can operate correctly and survive all kinds of bad weather without a murmur; a case in point is a Nexus premium 8 (with roller bearings like an Alfine 8 but with worse sealing). Following a proper lube job, I've had one of these stand outdoors in the rain for several years and it apparently hasn't suffered in any way.

cheers