Why I Dislike Greased Bearings
I have tried many different grease formulations on bearings. My conclusion is that *FOR ME* (only) greased bearings are a terrible idea. My reason is simple, they add too much drag. Yes, grease will become more viscous as the bearing temperature comes up and the amount of drag decreases. However, that additional performance in real world conditions still doesn't measure up to light mechanical oils.
A few caveats here. First off, I do bearing maintenance every eight hours (3 sessions) for rink skates. For Slalom, I service them pretty much every time. Some folks want long lasting lubrication. Grease is for those people. I have literally taken hundreds of bearings metrics (hmm, probably thousands actually). No performance-related testing I've ever done has ever made grease seem like a good idea for performance minded skaters.
White lithium grease has generally the best characteristics for skating from greases I've tested which include silicone, lithium (12-Hydroxy Stearate), axle, and assembly. However, it has all the problems with drag I cannot stand. It performs better when warmed up, but still isn't acceptable to me.
Still. There are three good reasons to use grease in my opinion.
- You aren't technical, hate working on your skates, and want your bearings to last for a very long time without any maintenance.
- You are skating using fully coated ceramic bearings which won't rust. You end up sloshing puddles all the time and your skates get very wet. You want a lube that won't wash out easily
- You are an engineer and want to smear the grease on a microscope slide to see how much metal and plastic are caught in the grease to judge other qualities of your bearing such as break-in.
I know some people love grease. I hope they are in one of those categories or they are missing out on using some other really effective lubricants such as light mechanical synthetic oil with metallic soaps. Oust MetOl is one of my top performers and (because I'm only around 145 pounds and clean & reapply often) Teflon silicone lubricants work well for me, too.
Comments
Bearings with grease offer little more(minute amounts) of drag compared to oils, when under loads. The drag is small in the big picture. The preservation of the bearings life is handled best by grease. Maintenance time is pretty much negated by grease. Wheels are the biggest variable, bearings are the most precise(least variables because of their precise properties). Variations in bearing drag are minute compared to variables in wheels. Comparing bearings is like comparing greases. As long as the bearing is good and smooth, grease is fine and lasts a very long time. As for overall speed, oils or greases, very small difference between them in the big picture.
While I agree completely with your assertions about grease & skate maintenance, I must respectfully disagree about the drag issue. I can definitely notice when bearings are newly greased and the grease is pretty packed. It feels awful to me as a rhythm skater and it decreases roll-out significantly in my weighted-skate testing and downhill testing. The numbers I have run from about 10% to 30% which would be fatal in most competitions. I'm always surprised when people say they can't notice or the results are "minute". Now having said that there is a huge difference between a cheap Chinese ABEC-3 furniture bearing compression-packed with silicone grease versus an enthusiast using the lightest white lithium grease applied with a sewing needle. If you are that guy, I agree, the difference is minute, but you'd still be better off with mechanical oil performance wise.
If you put in oil, you do bearing maintenance or see your bearings die much sooner than later. 10 to 30% of what? You skating 30 % slower? The most precise part of a skate is the bearing, logically it is the least component to affect your overall performance.
You definitely need more maintenance using oil. No argument there. Grease will pretty much always out-last oil. It definitely works for the "set it and forget it" skater. Personally, I oil indoor-use bearings every 8-10 hours of skating in most cases. To answer your question "of what": I mean distance. My main test is to simply see how far I roll coming off the same box ramp (I just take the average of three tries). I also use a weighted skate on the same box ramp. I walk out a 100M measuring tape in a line from the place where it left the ramp. So, these are real world tests under load. So, to restate what I mean another way, greased bearings typically only roll 70% to 90% as far as lightly oiled ones when using the same model bearings. I have tried with both Lithium and Silicone based greases. Silicone has the most drag by far for whatever reason in my testing. Lithium does a lot better but the volume of grease matters quite a bit, too. Your logic concerning precision seems like it's lacking in consideration of what poor bearing performance does to your skating (esp Speed & Slalom). The closest thing I could agree with would be that there isn't a huge difference in performance between good and great bearings. However, there is a tremendous gulf between great bearings and terrible ones. Throw some sand in your bearings and see how little they matter, *grin*.
Another thing to consider. Freshly greased bearings not run in(self clearanced greased areas inside the bearing). Since oil is so thin, it gets slung out all over the skate floor, kinda trashes out the floor for skaters depending on traction. AS oil reduces friction, increases slippage, it kills traction for others. Grease will move around inside the bearing over time, the bearing rolls better over time. A freshly greased bearing will always fail in your test.
@Fierocious1
Newly oiled bearings can shed oil if they are over-oiled, but this isn't a constant or much of a problem for someone who is experienced with the volume of oil needed. Surface tension will keep most of the oil close to the parts it's coating unless there is too much applied. If this is the case, one will see small "veins" of oil creeping out of the bearing onto the wheel/webbing after use and you know you've gone too far. Applying around 1 cubic centimeters of oil to a 608 bearing will result in little or no leakage as that is just enough to coat the annulus, balls, and cage but not enough to sling out due to centrifugal forces. I suppose there may be room for error and study in my assumptions about this.
One thing I definitely do agree on is that oil does not belong on the skate floor or wheel surfaces!
Sometimes I fully immerse bearings (sealed 608ZZ bearings) in 0W-10 motor oil. This results in a ton of extra oil coming out just like you mention. So, to mitigate this effect I have a wooden bearing holder that I pack them into and spin with an electric motor (same router motor I use for other testing which can spin at much higher speeds than most folks skate). That tends to work pretty well at slinging out the excess, and the wooden jury-rig catches the oil. I also wipe them off completely externally with a limonene soaked rag and lightly coat them with teflon so they don't attract so much dust.
To put it simply, the wheel becomes quicker as the bearings lubricate. The major reason to use bearing lubricant is to improve the rotational speed of the wheels through reduction of the friction ball. When the friction ball between the wheel and the road is decreased, a wheel may be utilized for a longer duration.
Grease is less dangerous on a skate floor. Noone wants to loose traction due to oil on the floor.