Wheel Bearing, Grease and Cup & Cone adjustment

[Yellow Saddle]

It will damage the seal when solid grease, as opposed to an 'oil' film forces its way past it. It is the oily component of grease that lubricates, hence the melting point of the grease should be appropriate for the generated heat in the bearing. I used to work on electrical motors & grease in the wrong place was certainly a problem! And grease in the wrong places will certainly attract dirt/grit.

Then I suggest you examine a wiper seal taken out of a bearing. You'll notice a tapered lip that easily moves out of the way of any pressurized grease and simply moves back in position again. No damage is done whatsoever. As I said, it actually requires the grease in order to live longer. It doesn't separate the oil from the soap either. That can't happen by the mechanism you describe.
Yes, grease does have a temperature rating but in cycling we don't care about that because the bearing is always at ambient temperature. It never heats up. There is also no problem with arc welding or spark ignition in our bearings either.
Grease does not attract dirt. It has no magnetic properties.
Dirt that does settle on exposed grease may get trapped but who cares, that's discarded grease and not working grease.

 

[Gravity Aided]

Here is a different situation:

Shimano are rather stingy with the amount of grease they pack the bearings in some new hubs. Would you top up with different grease or simply remove the existing grease and add new grease so all of the grease is of the same type?

@Gravity Aided Yes, marine grease keeps coming up as a good grease to use. The one I'm using also protects against salty water, etc.

A good idea, that, for when they salt the roads, or you do a coast to coast tour, and wheel dip in each ocean, or ocean and sea.

 

[Yellow Saddle]

Grease is an emotional subject with bicycle mechanics and DIYers, second only to chain oil. Endless claims are made about the merits of this or that grease. It appears that the more expensive the grease, the higher its praises are sung. Let’s look at the basics of grease.

Grease is just soap and oil. The soap provides a solid matrix for keeping the oil in place. Most general purposes greases are lithium-based. Lithium, if you can still remember your high-school chemistry, is number three on the periodic table, yet is a metal. It is so light that it floats on water. This amazing metal has a low melting point and when placed on water, immediately reacts with the water, melts and cruises around on top until it has completely disappeared into the water, leaving the water soapy to the touch. The white lithium oxide is the soap in lithium greases – soap being nothing other than an hydroxide of an alkali metal such as sodium, calcium or our lithium and an organic substance.

Although the alkali metals are highly reactive and so are their hydroxides, by combining them with organic substances they become very stable, with the reactive alkali metal strongly bonded to the rest of the molecule. The lithium in lithium grease is actually LIOH.

The active ingredient in grease is oil, thick or thin, chosen for the specific application. The soap is merely a carrier and dispenser of the lubricant and it is selected for its melting point and viscosity. Obviously, a lower melting point is not suitable for hot applications. The viscosity is an indication of how quickly the grease flows away from its original location. Lithium greases have a relatively high melting point but since cycling doesn’t produce any particularly hot bearings, this is largely irrelevant to us. Grease fails by going a.w.o.l. from where it is needed – a sign of too low viscosity.

Grease lubricates a friction interface by slowly seeping small amounts of oil onto the interface. We can say the soap “dispenses” the oil but has no lubricating function of its own. The soap is completely inert but the oil not. Very old grease can separate and here you often see blobs of soap and oil in the container. Just about any type of oil can be used in grease, including the stuff nature gave us, synthetic oil or any of the other lubricants made of silicone or molybdenum.

The fact that the soap is inert is misunderstood by companies like Rock Shox. They post dire warnings about the use of lithium grease in their forms, claiming that the lithium will somehow degrade the seals. This is nonsense, petroleum products degrade some polymers but not lithium. For some reason they don’t warn about petroleum products though. Any lithium grease is perfectly safe to use in MTB forks and won’t harm the seals. I suspect it has to do with sales of overpriced JudyButter.

Grease can have other alkali metals as its base and you may occasionally come across calcium or Sodium grease. Lithium grease is the common type and imminently suitable to cycling.

O-Ring and wiper seal companies understand the compatibility between their seals and many different many fluids and publish this data openly. There is nothing in a fork that is not compatible with standard seals, O-rings and rubber bumpers found in forks.

Boutique grease companies will tell you that the difference in their grease lies in the secret herbs and spices – a.k.a. additives. Most grease manufacturers add one or other anti-oxidant to their grease in inhibit oxidation (rust) of the wear parts. Grease designed for marine use has more than that for motor cars. This doesn’t mean the grease is waterproof.

Grease readily emulsifies and traps water by encapsulating the smaller water molecule inside large grease molecules, keeping it at the ready to attack unprotected metal parts. Grease shouldn’t come in contact with water, especially grease that is agitated, such as that in a moving bearing. It simply absorbs the water. The same goes for greasing dynamic joints such as quill stems, pedals and saddles. The movement pumps water into the interface and mixes it with grease. Once emulsified, it won’t evaporate and remain inside the grease, doing much harm.

Copper paste, used to prevent seize-up of mating metal parts and fusion of dissimilar metals, is not grease. It has no lubricant and was not designed for reducing friction, but for preventing fusion. It emulsifies less readily, but should still be watched and regularly changed when used in quill stems. These are best left ungreased.

Lithium grease is cheap and best purchased by the 500g can. One tin will last the average DIYer a lifetime. It works on your car, lawnmower and door hinges as well. I dispense it from a cheap plastic syringe. Cyclists apparently have plenty of used syringes lying around, so should have no excuse for a mess.

Not only is lithium grease cheap, it is also light in colour, which helps you identify contaminants. A bit of water ingression will quickly oxidize the steel inside and turn the grease brown. Replace immediately if you see this. It indicates a mixture of emulsion and rust – both are bearing destroyers.

The only place where lithium grease is not suitable for use on a bicycle, is in obsolete Shimano Octalink BBs with needle rollers. Grease doesn’t replenish itself very well in needle rollers. In a ball bearing, it churns and returns to the interface from where it was pressed out. In needle bearings it follows a one-way street – out. The same doesn’t hold true for Stronglight needle roller headsets, since the needles don’t rotate but only rock. This has problems of its own, but nothing to do with the type of lubricant used.

Whenever a bicycle was submerged in water, the grease needs to be replaced and bearings repacked. High-pressure washers are the enemy of bicycle bearings as is a rainstorm when the bike is on a roof rack on a fast-traveling car.

 

[Yellow Saddle]

[QUOTE 3552127, member: 9609"]Good post - I guess there are may different types of marine grease, but the only ones I have ever used (boat trailers) have that horrible smell that is found in Hypoid gear oils, I believe the smell comes from sulphur to give the oil extra strength to stop it breaking down within the grinding effect of hypoid gears. So what is the connection between these oils and marine grease ?[/QUOTE]
The ingredient in marine grease is calcium, which is odourless. Other greases typically use lithium soaps. You are right about the smell in some greases (and oils) and your instinct is right, it is sulphur. Sulphur clings to metal parts and even under high compression prevents metal-to-metal contact. Some marine grease may have sulphur added to make it high pressure marine grease. The sulphur doesn't counter the action of water, it merely adds high pressure properties. Both sulphurous grease and sulphurous oils are for high pressure applications. None exist in a bicycle application but if you have a tub of either, use it. Hypoid oil works fine on chains.

I use a hypoid oil to oil spoke threads before building a wheel. Although the oil isn't that smelly, it is interesting what happens when you start turning the nipples under tension. As you turn, it releases a little sulphur bomb. The smell isn't there when the nipple isn't turning. I don't have a chemical explanation for this phenomena but I do think the friction changes the sulphuric compound in the oil and one by-product is gaseous. Perhaps hydrogen sulphite.

 

[compo]

I'm just a luddite. I buy my grease from an agricultural merchant. Lithium grease in a 500g tub. If it is ok for mega expensive combines and other farm machinery my bike should be well protected.

 

[Spoked Wheels]

Those are Shimano's new "digital" bearings. They appeared about two years ago and after I've left the trade, so I've never seen them in the flesh. I've done the Shimano online course on adjusting them though but to be honest, I can't get my mind around it until I've seen them, seen them fail/not fail etc.

Shimano has a dilemma. It's bearings are the second-best in the industry and its products are the industry's most prolific. However, cup-and-cone bearings have a bad rap for all the wrong reasons, adjustment tricks included. I think "digital" is a noble attempt to eliminate that problem and get the rap right. Rather that than go for the inferior system of cartridge bearings.

Yes the new "digital" adjustment systems is definitely an improvement.

I know what I'm about to ask is not on topic but here it goes anyway

I wonder if the steel ball bearings grade 25 for the Dura Ace are about 3g lighter for a set of 13 balls than the standard shimano ball bearings. Is it just the weight or also the better grade will translate to a longer service life? I'm thinking that most people don't go for the Dura Ace grease so.... maybe the better grade bearings hardly make a difference. And while we are on the subject, I know that Dura Ace hubs have very good seals but I wonder if there is any advantage in using ceramic balls.

 

[Yellow Saddle]

Yes the new "digital" adjustment systems is definitely an improvement.

I know what I'm about to ask is not on topic but here it goes anyway

I wonder if the steel ball bearings grade 25 for the Dura Ace are about 3g lighter for a set of 13 balls than the standard shimano ball bearings. Is it just the weight or also the better grade will translate to a longer service life? I'm thinking that most people don't go for the Dura Ace grease so.... maybe the better grade bearings hardly make a difference. And while we are on the subject, I know that Dura Ace hubs have very good seals but I wonder if there is any advantage in using ceramic balls.

I can't see why they would be lighter. Steel is steel, size is size.
There is no advantage to hybrid bearings, which are ceramic balls on steel races or vice versa.
Ceramic bearings have their origins in super high speed applications like turbo chargers where the bearing's centripetal force is enough to deform it and make it loose contact/preload. We don't have that in cycling, not even I, who am very fast.
Ceramic balls on steel races actually make for a poor bearing - the balls being much harder than the steel overloads the race and causes surface cracks or "orange peeling" on the race.
It is quite possible to get grade 5 bearing balls from Enduro on the US so tI don't see the need for ceramic balls. However, putting grade 5 balls in a grade 20 race is like caviar on brisket.
Balls of steel and a nice ride with a beer afterwards. Is there more to life than that?

 

[Spoked Wheels]

I can't see why they would be lighter. Steel is steel, size is size.
There is no advantage to hybrid bearings, which are ceramic balls on steel races or vice versa.
Ceramic bearings have their origins in super high speed applications like turbo chargers where the bearing's centripetal force is enough to deform it and make it loose contact/preload. We don't have that in cycling, not even I, who am very fast.
Ceramic balls on steel races actually make for a poor bearing - the balls being much harder than the steel overloads the race and causes surface cracks or "orange peeling" on the race.
It is quite possible to get grade 5 bearing balls from Enduro on the US so tI don't see the need for ceramic balls. However, putting grade 5 balls in a grade 20 race is like caviar on brisket.
Balls of steel and a nice ride with a beer afterwards. Is there more to life than that?

So, not sure I got your points.
No advantage of grade 25 bearings over standard bearings.

Ceramic balls don't make good cycling ball bearings.

Ball bearing grade 5 are far superior. Superior lasting life or superior performance?

 

[Yellow Saddle]

So, not sure I got your points.
No advantage of grade 25 bearings over standard bearings.

Ceramic balls don't make good cycling ball bearings.

Ball bearing grade 5 are far superior. Superior lasting life or superior performance?

There is no advantage to mixing grade 25 and grade 5. The lowest common denominator wins.
A smoother ball or race will both last longer and run smoother but I hesitate to say so, especially the latter, because a well-adjusted Grade 25 bearing lasts a very long time and rolls so smoothly that an improvement using a smoother bearing is just about immeasurable.
Bearing balls and races are not hardened uniformly throughout. The outer shell is harder than the inner substrate and a loaded bearing that runs on a race dents the race (and vice versa) where it rolls. If there is an imperfection, called an aspherity in bearing talk, and the imperfection is say, a little pimple on the surface of the ball, it goes without saying that the pimple will receive more compression than the surrounding ball. That compression fatigues the hard shell of the bearing and it breaks away, removing adjacent material. This contaminates the grease and obviously is not good for the bearing. Thus, smooth bearings last longer. But as I say, "longer" is subjective. Usually a well-adjusted bicycle bearing fails from ingression long before it wears out.
If the cones are too loose, only one or two balls are loaded and they are thus overloaded - again leading to breakout of material. This happens only on one position of the cone.

If the cones are too tight, the entire ring is overloaded and failure is either a breakout of material right around the cone or, sliding damage as the balls slide around the cone.

Further, "roll" is used judiciously above, since a ball half rolls, half slides in a cylindrical bearing. The only bearing where it rolls perfectly without sliding is a linear bearing that approximates a train wheel on a track.
Smoother bearings are nice, but not necessary better in the bigger scheme of things. Cheap bicycles have class 100 bearings and class 25 is already 4 times smoother, which is good enough. Going smoother brings diminishing returns but much higher costs. Exponentially higher in most cases.

Cartridge bearings are a very poor choice of bearing for a bicycle wheel. They are designed for radial loading only but receive lots of lateral loading. This damages them very quickly and they fail before their seals wear out, their grease expires or the balls have any chance to start wearing down. Here smoother gives no advantage since a smooth or rough bearing has no protection against incorrect loading.

 

[Spoked Wheels]

All very interesting @Yellow Saddle. Reliability is the key for me and while reading your post I immediately thought about a Dura Ace hub that I bought on gumtree over a year ago and I fixed the other day by replacing the loose ball bearings. I'm pretty sure the ball bearings I used were just ordinary ball bearings, probably grade 100. I was very happy that the gamble I took paid off.... the hub was only £10 and it is in great condition, only a few balls were damaged. Now, that I'm using ordinary grade bearings am I at risk of damaging the racers? Assuming they are correctly tightened Which brings me to the other point, I now have 2 full sets "digital" adjusting Dura Ace hubs and what you were saying about the importance of correct adjustmet is going to be tricky as I'm not sure whether to follow Shimano guidelines and adjust the cone so that there is no play, when I now know that if I leave a very small amount of play and I close the QR tight while the hub is on the wheel stand, that small amount of play is now gone. There is very little information out there on adjusting these hubs. Shimano guidelines are clear and easy, that is why they came out with this system, adjust until there is no play. I guess, untill there is more feedback on these hub I'll have to follow the guidelines and monitor the hubs closely.
Thanks ever so much for all the information. It's great stuff.

 

[Yellow Saddle]

All very interesting @Yellow Saddle. Reliability is the key for me and while reading your post I immediately thought about a Dura Ace hub that I bought on gumtree over a year ago and I fixed the other day by replacing the loose ball bearings. I'm pretty sure the ball bearings I used were just ordinary ball bearings, probably grade 100. I was very happy that the gamble I took paid off.... the hub was only £10 and it is in great condition, only a few balls were damaged. Now, that I'm using ordinary grade bearings am I at risk of damaging the racers? Assuming they are correctly tightened Which brings me to the other point, I now have 2 full sets "digital" adjusting Dura Ace hubs and what you were saying about the importance of correct adjustmet is going to be tricky as I'm not sure whether to follow Shimano guidelines and adjust the cone so that there is no play, when I now know that if I leave a very small amount of play and I close the QR tight while the hub is on the wheel stand, that small amount of play is now gone. There is very little information out there on adjusting these hubs. Shimano guidelines are clear and easy, that is why they came out with this system, adjust until there is no play. I guess, untill there is more feedback on these hub I'll have to follow the guidelines and monitor the hubs closely.
Thanks ever so much for all the information. It's great stuff.

Don't worry about the Grade 100 balls in there. But regularly spin the wheel by hand as I described and feel for broken balls. Just in case.
I'll answer the digital adjustment question of yours, which I think is valid, with a general description of how to adjust the wheel bearings. You'll immediately see how to test your "digital" setting as well.

1) The key to adjusting wheel bearings on wheels that don't have on-the-bike adjustment systems like Campag or Fulcrum, is to have just the right amount of axle play when the wheels is off the bike, so that when you clamp the QR, that play goes away.However, you don't want negative play because that would then overtighten the bearings. The latter is hard to judge.
2) Clean, replace, reassemble the bearings and start adjusting. Feel for movement by strongly buy slowly wiggling the axle up and down. You want to be able to feel a little bit of mechanical movement in the axle. How much is "little"? Trial and error will tell you. Don't worry, you won't get it right first time and even if you do, you won't repeat that trick the second time, I promise you that.
3) Once you are satisfied that your cones are just right when the jamb nut is tight. proceed to install the wheel.
4) Make sure nothing on the bike touches the wheel. Brakes open (disc pads out if needed) and chain OFF.
5) Install the wheel and lightly tighten the QR. Conform that the wheel still has play by moving the tyre end sideways and feeling the feedback from the cones bashing against the balls inside the hub. You will have about 1mm movement at the tyre.
6) Now open the QR again, crank up the nut and close it forcefully. It should leave a white mark in your palm that will disappear over about 10 seconds. Don't put the QR lever in line with a frame tube, because it will be so tight that you will struggle to get your fingers in there and open it.
7) Now conform that all movement has gone and the pay has been taken up by the compressing axle. There will be no play anymore. Don't confuse wheel flex with play. Play gives mechanical feedback, flex doesn't
8) Now you are sure that it is not too loose, but is it not perhaps too tight? Let's test.
9) Slowly spin the wheel - very slowly and watch it come to a stop. Note what part of the wheel settles at the bottom. It should be the heaviest, like the valve (or in tubeless, the congealed mess of sealant inside).
10) Repeat the process in 9) and see if it settles at the same place again. If it does, you know the cones are just right. If it settles randomly, the cones are too tight. Remove and repeat the necessary steps.
Campag wheels allow you to adjust the cones on the bike and lock the cone with an allen key. This is nice and quick. Great system.
On your digital wheels, you should still test if it is too loose or too tight. But I suspect the process will be much easier, especially after the first time. On standard wheels it isn't easy and don't expect to get it right first time. But it is important. Practice.

 

[Tim Hall]

Grease is an emotional subject with bicycle mechanics and DIYers, second only to chain oil.


<snip>

The only place where lithium grease is not suitable for use on a bicycle, is in obsolete Shimano Octalink BBs with needle rollers.

What about Shimano Roller brakes? The grease Shimano recommend for these is made of ground up unicorn horns, going by the price. Or is it a lithium based grease with expensive herbs and spices? I'm guessing temperature resistance of the grease is more of an issue with brakes than it is with wheel bearings, and am a bit disinclined to carry out experiments with cheaper grease subsitutes.

 

[Yellow Saddle]

What about Shimano Roller brakes? The grease Shimano recommend for these is made of ground up unicorn horns, going by the price. Or is it a lithium based grease with expensive herbs and spices? I'm guessing temperature resistance of the grease is more of an issue with brakes than it is with wheel bearings, and am a bit disinclined to carry out experiments with cheaper grease subsitutes.

I have no experience of those. In my market these were not available. I can't even guess, 'cause I don't know where the stuff goes, whether it is subject to lots of heat or what. The special oil in internally-geared hubs is necessary because other oils could polymerise and coat the internals in a brown glaze.

 

[Spoked Wheels]

Don't worry about the Grade 100 balls in there. But regularly spin the wheel by hand as I described and feel for broken balls. Just in case.
I'll answer the digital adjustment question of yours, which I think is valid, with a general description of how to adjust the wheel bearings. You'll immediately see how to test your "digital" setting as well.

1) The key to adjusting wheel bearings on wheels that don't have on-the-bike adjustment systems like Campag or Fulcrum, is to have just the right amount of axle play when the wheels is off the bike, so that when you clamp the QR, that play goes away.However, you don't want negative play because that would then overtighten the bearings. The latter is hard to judge.
2) Clean, replace, reassemble the bearings and start adjusting. Feel for movement by strongly buy slowly wiggling the axle up and down. You want to be able to feel a little bit of mechanical movement in the axle. How much is "little"? Trial and error will tell you. Don't worry, you won't get it right first time and even if you do, you won't repeat that trick the second time, I promise you that.
3) Once you are satisfied that your cones are just right when the jamb nut is tight. proceed to install the wheel.
4) Make sure nothing on the bike touches the wheel. Brakes open (disc pads out if needed) and chain OFF.
5) Install the wheel and lightly tighten the QR. Conform that the wheel still has play by moving the tyre end sideways and feeling the feedback from the cones bashing against the balls inside the hub. You will have about 1mm movement at the tyre.
6) Now open the QR again, crank up the nut and close it forcefully. It should leave a white mark in your palm that will disappear over about 10 seconds. Don't put the QR lever in line with a frame tube, because it will be so tight that you will struggle to get your fingers in there and open it.
7) Now conform that all movement has gone and the pay has been taken up by the compressing axle. There will be no play anymore. Don't confuse wheel flex with play. Play gives mechanical feedback, flex doesn't
8) Now you are sure that it is not too loose, but is it not perhaps too tight? Let's test.
9) Slowly spin the wheel - very slowly and watch it come to a stop. Note what part of the wheel settles at the bottom. It should be the heaviest, like the valve (or in tubeless, the congealed mess of sealant inside).
10) Repeat the process in 9) and see if it settles at the same place again. If it does, you know the cones are just right. If it settles randomly, the cones are too tight. Remove and repeat the necessary steps.
Campag wheels allow you to adjust the cones on the bike and lock the cone with an allen key. This is nice and quick. Great system.
On your digital wheels, you should still test if it is too loose or too tight. But I suspect the process will be much easier, especially after the first time. On standard wheels it isn't easy and don't expect to get it right first time. But it is important. Practice.

I've had Shimano hubs for years so I already have some experience with cup and cone adjustment but you are offering some details in your post that I wasn't aware of and I feel that it would complement rather well my experience. I thank you for that cause I thinks it's quite a useful technique for the proper adjustment of cup and cone hubs - I love it

I'm thinking that I can use my wheel stand to carry out the procedure and look for that 1mm movement of the tyre more easily but a wheel and the frame + rim brake callipers can just as well be used.

As you say, it does take a lot of trial an error sometimes to find the right amount of play. Using spanners can be even more tricky cause the amount of play can easily disappear while locking the cone and nut, before the QR has a chance to lock the wheel, so one ends up leaving play that is not so little after all, I guess t's all down to mastering the technique and what works best for you.

 

[Yellow Saddle]

As you say, it does take a lot of trial an error sometimes to find the right amount of play. Using spanners can be even more tricky cause the amount of play can easily disappear while locking the cone and nut, before the QR has a chance to lock the wheel, so one ends up leaving play that is not so little after all, I guess t's all down to mastering the technique and what works best for you.

There's the difficulty.