Oil instead of grease?

[Mick F]

I was greasing my hubs yesterday afternoon. Easy job really with my hubs.

It put me in mind of the idea of drilling the shells so grease injection could be done without much fuss. Then I wondered if you could oil them, rather than grease.

A few drops of oil from can into the hole could be done frequently and easily.

Is there a downside?

[meic]

I used to oil my hubs when I was school kid.

I do remember rivers of dirty oil running down the spokes onto the (steel) rims to improve the effectiveness of my brakes.

[Brucey]

i have run hubs with (new, unworn) full contact seals in oil quite successfully. It is arguably a better arrangement than grease because the seal lips are always wetted with oil, and therefore are less likely to either wear or let water in. Greased hubs let the water in past the seals when the seal lip isn't wetted with lubricant any more; immediate water ingress or wear then water ingress will result.

With oil inside, there is always some oil leakage, but if the seals are in good condition when you start using oil then leakage is typically not excessive.

With rear shimano freehubs, the oil leaks out through the freehub body if the seal there (if there is one at all, that is...) is not effective. In this case oil isn't such a good option for long-term use.

I recently pulled a bike out of the shed I'd not ridden for two or three years. The hubs (ultegra, drilled for oil ports) were oil lubricated and ran perfectly smoothly without any attention (e.g. I could -with the QR loose- hear the balls in the front hub 'ticking' as they fell over the top, and the wheel always settled to the heavy spot under its own weight with the wheel in the bike).

I am presently experimenting with my thixotropic semi-fluid grease in various hubs that are not perfectly sealed. I am hoping that it will wet seal lips effectively and confer other oil-like benefits, whilst being a better lubricant and causing less outward leakage past imperfect or slightly worn seals.

cheers

[Vantage]

I wouldn't have thought oil was a heavy/thick enough lube to withstand the constant punishment that hub bearings take. Isn't there a cushioning effect from grease to think about?

[Valbrona]

I wouldn't have thought oil was a heavy/thick enough lube to withstand the constant punishment that hub bearings take.?

Exactly.

And MickF, I think you just need to track down a grease gun with a long enough nozzle, like the nozzle on your oil can.

[Brucey]

grease is simply oil mixed with a thickener.

The thickener is not a lubricant. It contributes very little benefit to the lubrication properties; it just holds the lubricant in the vicinity of the bearing, so that the oil doesn't leak away when the machine isn't in use. [When the machine is in use, and is hot, the grease may be very much more fluid BTW.] Where possible in all kinds of machines, oil is used in preference to grease for many kinds of lubrication purposes. If there is a choice, the choice is often made on the basis of whether oil will simply leak out of the component at an unacceptably high rate or not.

For the lowest low running friction, oil is better than grease, because although the soaps etc used in greases are to some extent thixotropic (i.e. they don't require proportionately more effort to shear at high speeds than low speeds) they still consume some power when they are sheared, and this always increases with speed. You can't even use ordinary grease in very high speed bearings, because it overheats catastrophically.

Arguably all the thickener can do is make the lubrication worse when cold and at low (bicycle bearing) speeds since the grease gets pushed out of the way by the balls ('channeling') and may not find its way back again before the next ball comes along. Additives which help avoid this are not always present and in any event may be the first element of the grease to degrade in service. By contrast oil will find its way everywhere it needs to go under similar conditions.

Another factor is the base oil viscosity that is used. Greases are often made with quite light oils e.g. so that the grease still works OK when it is cold, and doesn't overheat itself too badly when run at 10000 rpm. If you use a thicker oil (by itself or in a grease), this always improves the load bearing capacity of a bearing at lower (bicycle) speeds. Greases with high base oil viscosities are not common; I use Castrol SBX grease because it does have a very high -about 1000cSt- base oil viscosity.

Both oils and greases can be loaded up with other additives ( EP additives, solid lubricants etc) which do change the lubrication properties especially at high loads and low speeds; again of great interest for bicycle use (and again present in SBX grease).

So overall, provided it doesn't leak away too fast, or cause some other problem, oil -the right oil- is usually a better lubricant for many bearings. Grease is usually best thought of as just oil; oil that hangs around better, at some other cost.

cheers

[Kenn]

In the 1960s the hubs on my first Mercian had oil ports which I oiled with couple of drops of hypoid gear oil ( The thickest I could find) every couple of weeks. The bearings needed little attention despite covering circa 1000 miles per month for years. My current Campag Record hubs also have oil ports which I don't use - I now have the time to disassemble and re-pack the hubs every year and the wheels stay cleaner. Not sure which approach is best - both seem to work.

I believe the Rohloff hub relies on oil leaking through the bearings to lubricate them, which gives some confidence in the oil approach given Rohloff's reputation for reliability.

[Valbrona]

grease is simply oil mixed with a thickener.

Yes, in the case of your smelly old fashioned petroleum-based grease used by older members of the cycling fraternity. Your average bicycle grease nowadays is PTFE/Teflon based or contains ceramic particles.

[Valbrona]

grease is simply oil mixed with a thickener.

Yes, in the case of your smelly old fashioned petroleum-based grease used by older members of the cycling fraternity. But your average bicycle grease nowadays is PTFE/Teflon based or contains ceramic particles.

[Brucey]

grease is simply oil mixed with a thickener.

Yes, in the case of your smelly old fashioned petroleum-based grease used by older members of the cycling fraternity. But your average bicycle grease nowadays is PTFE/Teflon based or contains ceramic particles.

yes but those ingredients are a tiny volume fraction -the worth of which is rather questionable- in the greases in question, which in fact comprise mostly (and more usefully...) oil and thickener, just like most other greases.

The 'teflon' and 'ceramic' additives in some bicycle specific greases are put there primarily for marketing-BS value, to reel in the gullible 'cyclist in the street'. You will notice that the percentages of these 'magic additives' and/or their mechanism of operation is not disclosed or backed up with any evidence. Nor indeed in other applications with similar (or more demanding) usage conditions are such 'magic additives' found. This doesn't necessarily make the bicycle greases bad greases, it just doesn't make them good for the BS-drivel-ridden reasons they claim... I'm afraid that the marketing of some lubricants has descended to the same level as, say, that of shampoos; the people concerned have disappeared so far up their jacksies that they will happily practically ignore the primary purpose of the product ('it gets your hair clean'/ 'it keeps oil in contact with your bearings') and they are selling it on the basis of all kinds of dubious -or perhaps even imaginary- secondary attributes.

The main benefit of the good bicycle greases (with or without magic-BS ingredients) is that they may have a fully synthetic base oil with high viscosity blended with a thickener that resists separation and washout reasonably well. The rest of it is largely hype. Whilst some of these greases work OK and have other benefits (like they might be largely non-toxic, they are a nice clean colour and don't muss up your clothes etc) they are almost certainly not the best lubricants for the task in hand.

For the best lubrication of low speed bearings under high load, you need to look at some heavy-duty industrial greases. These may be toxic, messy, ruin your clothes, stink to high heaven, genuinely cost a fortune to make, etc but are very much superior lubricants under the highest loads and most arduous conditions. They contain synthetic base oils of high viscosity, and controlled percentages of additives proven to reduce wear under these conditions, better resist washout, inhibit corrosion, prevent galling, seizure etc. These lubricants are used to ensure that machinery and processes costing millions operates properly. If the performance of these lubricants was genuinely enhanced by 'ceramic' and/or 'teflon' additives then they would use them; as it is, you won't find this kind of snake-oil-BS in such lubricants, which should tell you everything you need to know about them.

cheers

[rootes]

if you want to do this... not sure why as grease is the correct thing for hubs,, but you could try a thick oil like say EP140 gear oil... which is so viscous it is more like a grease (interesting is a written alternative to grease for cars with Kingpins that require lubricating)

really only place for oils in bikes is on the chain and really in an oil bath..

grease is for when the lubricant is required to stay in/on the item to be lubricated whereas oil is better as a bath or flowing though the item to be lubricated.

[breakwellmz]

Bikes used to have lubrication ports for BB and headset bearings.I think they must have been for oil,if you pumped grease in them most of it would go where you didn`t want it i suspect.

[Geoff.D]

I was born in 1949, to cycling parents and a Dad who couldn't throw anything away. So, our cellar was a workshop full of bits and pieces. From the late 50's I was cutting my teeth on maintenance tasks, not least because there seemed to be an endless supply of old bikes left on derelict sites in our neighbourhood. Coupled with all my Dad's bits, I was able to resuurect old wrecks into usable wrecks.

I definitely remember that there were grease nipples in some bottom brackets, as well as oil ports in wheel hubs. I'd pump grease into the BB until it began to emerge around the axle (cottered of course). Initially it would be the old grease that emerged (dirty) and then signs of clean stuff. At that point I'd stop. With hindsight, this was overkill, of course, because it filled the "empty" space within the BB as well as the races. I seem to remember that I could do this on some wheel hubs as well, but I'd stand corrected on this.

To this day I'm appreciative of my parents allowing and encouraging me to "get my hands dirty" in this way. Skills and knowledge learned by "doing"!!

[Mick F]

To this day I'm appreciative of my parents allowing and encouraging me to "get my hands dirty" in this way. Skills and knowledge learned by "doing"!!

+1

[Brucey]

IIRC old-style hubs were usually fitted with oil ports, headsets with grease nipples and BB shells could be fitted with either.

BTW 140W gear oil is usually oil with a viscosity of ~140cSt @ 40C, plus various additives (depending on the spec). You can buy gear oils up to ~400W (i.e. ~400cSt @ 40C).

Although these oils are thicker than some base oils used in standard greases, they are still not as viscous as the base oil in heavy duty greases for low speed applications.

cheers