Abec-5 vs. Abec-7 vs. Abec-9

[Rance]

So what's the difference between these bearings? Any reason I should not use the 5's or the 9's? And would you recommend the ZZ's or the 2RS's? Thanks.

[buscht]

Originally Posted by Rance So what's the difference between these bearings? Any reason I should not use the 5's or the 9's? And would you recommend the ZZ's or the 2RS's? Thanks.

About ABEC Ball Bearings
Precision ball bearings are rated according to ABEC (Annular Bearing Engineers Committee) grades. The higher the ABEC grade, the better the bearing. Tolerances are the major differentiating factor between ABEC grades (e.g. ABEC-5 ball bearings have tighter tolerances than ABEC-1).
Load— The dynamic rating for the radial load (except where noted) a bearing can endure for one million revolutions.
Speed— A bearing's maximum speed tolerance at low loads, expressed in rpm.
Tolerances

Inch Sizes ABEC-1 ABEC-5

For Shaft Dia.
0.004"-0.709" +0 to -.0003" +0 to -.0002"
0.710"-1.181" +0 to -.0004" +0 to -.0002"
1.182"-1.969" +0 to -.0005" +0 to -.0003"
1.970"-3.15" +0 to -.0006" +0 to -.0004"
OD
0.125"-0.709" +0 to -.0003" +0 to -.0002"
0.710"-1.181" +0 to -.0004" +0 to -.0002"
1.182"-1.969" +0 to -.0004" +0 to -.0003"
1.970"-3.15" +0 to -.0005" +0 to -.0004"
3.16"-4.724" +0 to -.0006" +0 to -.0004"
4.725"-5.90" +0 to -.0007" +0 to -.0005"
5.91"-7.087" +0 to -.0010" +0 to -.0005"
Width*
0.004"-0.394" +0 to -.0050" +0 to -.0015"
0.395"-0.709" +0 to -.0050" +0 to -.0030"
0.710"-1.969" +0 to -.0050" +0 to -.0050"
1.969"-3.15" +0 to -.0060" +0 to -.0060"
* Width tolerance is based on "For Shaft Dia." sizes.
Metric Sizes, Tolerances, mm

mm ABEC-1 ABEC-3 ABEC-5 ABEC-7

For Shaft Dia.
2.5-18 +0 to -.008 +0 to -.007 +0 to -.005 +0 to -.004
19-30 +0 to -.010 +0 to -.008 +0 to -.006 +0 to -.005
31-50 +0 to -.012 +0 to -.010 +0 to -.008 +0 to -.006
51-80 +0 to -.015 +0 to -.012 +0 to -.009 ——
OD
6-18 +0 to -.008 +0 to -.007 +0 to -.005 ——
19-30 +0 to -.009 +0 to -.008 +0 to -.006 +0 to -.005
31-50 +0 to -.011 +0 to -.009 +0 to -.007 +0 to -.006
51-80 +0 to -.013 +0 to -.011 +0 to -.009 +0 to -.007
Width*
2.5-10 +0 to -.120 +0 to -.120 +0 to -.040 ——
11-18 +0 to -.120 +0 to -.120 +0 to -.080 +0 to -.080
19-50 +0 to -.120 +0 to -.120 +0 to -.120 +0 to -.120
51-80 +0 to -.150 +0 to -.150 +0 to -.150 ——
* Width tolerance is based on "For Shaft Dia." sizes.

Go to Mcmaster.com and look up bearings.

[Rance]

Found my own answer...

Copied from http://www.epinions.com/content_151121464964

[
Bearings are probably the least understood item in skating equipment. Understanding ball bearings in full could require reading a 1,000 page engineering textbook and still there would likely be issues not fully covered. Fortunately, in skating one does not need to go that high tech.

Ball bearings are important for ultimately they are the reason we can all skate. The world is full of bearings: they are inside the wheels of your inline skates, the vacuum cleaner or the air-conditioner you use at home, etc... However, air-conditioners work with a relatively slow number of rotations per minute (rpm) while vacuum cleaner engines perform at high number of rpm's. This is an interesting issue into which I will go briefly and that I think you will find very compelling as well. But, before I do that, allow me to explain first that basically for inline skates there are 3 different kind of ball bearings being used these days:

- standard bearings (known as 608)
- mini bearings (known as 698)
- micro bearings (known as 688)

The difference is size: the 688 being the smaller, the 608 the larger. This means that 608 bearings, and BSB Swiss are 608 bearings, are also the heaviest kind. However, one should not forget, that smaller bearings are used in wheels with longer spokes and hence in the end the gain weight is not always so dramatic as those in favor of 688 bearings would like for you to believe. All this means also that the steel balls inside the ball bearings are bigger for a 608 than they are in a 688. Some say that 608 bearings are better at carrying side loads and this is the case when one skates past the very beginner level and begins to develop an outside angle in his/her skating stroke. Others insist that 688 bearings have better acceleration because of smaller steel balls. Then, 608 advocates, will tell you that 608 bearings last longer. And so on. To make a long story short, unless you go heavily into the physics behind ball bearings, you will never know who is right or wrong. And, even if you did that, you are still likely to come out not knowing which ball bearing is really best in all situations.

608 bearings are assigned a quality using the acronym ABEC and a number. For skating you will find that there are 3 of these bearings ABEC1, ABEC3, ABEC5, ABEC7. ABEC9 exists but as far as I know it is not used in skates. What do these numbers mean? Well imagine the perfect ball bearing, the ABEC10, this means perfectly round balls, perfectly built raceways, and so on... ABEC9 is very close to that standard, ABEC7 is still excellent, but not so close to the theoretical perfection, and less and less so as you move down to ABEC1. Often not having an ABEC does not mean that the ball bearing is cheap. Sometimes, simply they are not tested to be assigned an ABEC number. Why do we need an ABEC? The answer is very simple: in a motor that rotates at slow speed, small imperfection in the bearings are unlikely to create damage to the system (air-conditioner), but if the motor works at very high rpm's (vacuum cleaner, e.g.) it could be damaged by cheap bearings.

A table that is very informative is the following where for each of the 4 ABECs it is listed the max number of rpm's each is meant to safely work at:

===============================
ABEC 1 less than 25,000 rpm
ABEC 3 less than 32,500 rpm
ABEC 5 less than 37,000 rpm
ABEC 7 less than 43,000 rpm
===============================

The next point is to translate these limit rpm's in skater's speeds. To do that consider a skater with 80mm wheels. Simple algebra shows that:

ABEC1 is good for skaters going up to 190kmh (or ~110 mph);
ABEC3 is good for speeds up to 245 kmh (or ~152 mph)
and so on..

I am sure that skaters are happy they don't need super-ABECs.

ABEC is mostly hype. In fact, true experts will tell you that ABEC without reference to materials is useless. Imagine a ball bearing built to ABEC9 standards, but using very cheap steel. Chances are the balls and the raceways will quickly deteriorate and you will have ABEC7, ABEC5 and eventually you will quickly end up with a non ABEC ball bearing.

So the first lesson we learn is: MATERIALS COUNTS FOR MORE THAN ABECs and BSB SWISS do not carry an ABEC, but they are made of some of the best steel out there. This means that they will perform well and over a long period of time if proper maintenance is done . And that's all that matters.

Maintaining bearings is not difficult, but it is certainly time consuming. Who wants to open 16 or 20 bearings, wash them, grease them, seal them and so on?

As Richard Nett explains on his website, BSB Swiss bearing are ideal to save you a lot of work because they are grease packed. You need to put on 50 or 100 miles before you do a race with them, but they last much longer than an oiled bearing. As you skate on them the grease gets spun up against the shield where the inner race meets the shield and creates a barrier between the contaminants trying to get in and the balls and inner race. Bones Swiss, for example, are oiled bearings used by top athletes in speedskating. They are ready to race immediately out of the box. Unfortunately, within 10-15 minutes one can hear dirt grinding in the bearing.

With the BSB it is not unusual to go 6 months or more before hearing the sound of dirt in the bearing.

However, one has to be aware that both the BSB and the Bones bearing the balls and race come polished with a mirror finish and that scratching that mirror finish will cause resistance. BSB mirror finish can last a year if you don't go through water (if you do they are instantly ruined) and push the grease and dirt into the race.

The BSB are packed with the right amount of low temperature grease (as opposed to a high temperature grease) which will liquefy at a low temperature. This is good in that if and when a race becomes dry (insufficient lubrication) and friction starts, the friction by generating heat causes the surrounding grease to melt and relubricate the balls and race.

You may hear about bearings with ceramic balls. Those are truly expensive. A set of 20 bearings could easily cost in excess of $200+. They are superior, it is a fact, at least on a theoretical ground since ball bearings develop heat inside, and ceramic balls are better at dissipating it. The idea is that as the heat increases, ball bearings and raceways expand and they tend to create more friction. While this is true, it is questionable that such bearings are needed at the speeds that are typical of inline skating. So no need to go that high-tech unless you are a serious racer contending for world titles.
]

[buscht]

Sorry about the lack of columns in that table. They disappeared when I posted the list.

[Rance]

buscht,

You beat me by a minute but thanks for the additional info. though.

So what about the 2RS vs. the ZZ. I know it references the covers but which one works better for 'our' purpose? Thanks.

Rance

[mxtras]

ABEC is meaningless??

Believe it or not, bearings are used for things other than skating - hard to believe but it's true.

2RS = 2 rubber seals
ZZ = 2 steel shields

The seals will seal and the shields will shield. The seals create more friction but provide a substantially greater degree of protection from garbage and lubrication loss.

Scott

[JFettig]

I dont know if that explanation was quite correct, I think someone once told me that it has to do with the tollerances. Thats something to look up. You can't take a roller bladers word for it

Its something to look into. I found some bearings that can handle 80k that I may use in my skateboard sometime


Jon

[Rance]

I went for the ones with the rubber seals (arf, arf, arf [seal sounds] ). I got 32 bearings for $17 (ebay, buy it now). This should do me for now.

Thanks for the comments guys.

[jetpig1]

OK, I am doing R and D for a skateboard manufacturer. I received a bunch of parts and such for assembly and testing of current stuff, some in conjunction with my new designs(mostly trucks, for now). He gives me some ABEC 3's and says the whole hub bub about bearings is BS. Having played rollerhockey, I know the difference from ABEC 3's to 7's is like gravel road to smooth ice.

I wonder, also, being a machinist for 15 years mind you, if the fellas commenting on bearing ratings have actually skated on them .... yes I know there are other apps, but hockey rules...

I will NOT be skating at 150 mph, but the ride difference is significant with the increased ABEC rating. I also hear tell of ceramic bearings that are significantly better.....

Comments ?

[CarveOne]

Originally Posted by jetpig1 OK, I am doing R and D for a skateboard manufacturer. I received a bunch of parts and such for assembly and testing of current stuff, some in conjunction with my new designs(mostly trucks, for now). He gives me some ABEC 3's and says the whole hub bub about bearings is BS. Having played rollerhockey, I know the difference from ABEC 3's to 7's is like gravel road to smooth ice. I wonder, also, being a machinist for 15 years mind you, if the fellas commenting on bearing ratings have actually skated on them .... yes I know there are other apps, but hockey rules... I will NOT be skating at 150 mph, but the ride difference is significant with the increased ABEC rating. I also hear tell of ceramic bearings that are significantly better..... Comments ?

Yes, from a purely scientific viewpoint, please explain how a mere mortal human skate boarder or hockey player can actually feel the difference between the ABEC3 and ABEC7 (or 9) bearings when any surface that a skate boarder or hockey player rolls on is thousands of orders of magnitude rougher on the surface than the bearing's surfaces?

Inquiring minds want to know.

This is beginning to fall into the CDs vs vinyl records realms of thought. (oops, now I've really done it )

Maybe the different ABEC classes depends on how long a Chinese laborer is allowed to hand polish each of the ball or roller bearings before stamping the classification the final bearing assembly.

No offense intended here jetpig1, just having fun with this whole train of thought that is developing.

CarveOne

[HuFlungDung]

CarveOne,
I think the balls are produced in a little town called Abec7

[CarveOne]

Originally Posted by HuFlungDung CarveOne, I think the balls are produced in a little town called Abec7

That sounds just as plausible as my theory.

CarveOne