3. Is there a lower grade than ABEC 1 ?

	There is no GRADE lower than Abec 1, but that doesn't mean that a
	manufacturer has to meet ABEC standards. There are a lot of minor bearing
	manufacturers that are not publishing any data on their manufacturing
	standards, so beware. Stick to brands that are well known and you won't go
	wrong.

	4. Are there any other standards for measuring Bearing precision ?

	Yes. The other commonly used standard is the ISO (International Standards
	Organisation) standard.  There are slight differences in the standards
	applied, but basically ISO Grade P0 is approximately equal to ABEC 1, ISO
	P6 approximates ABEC 3, ISO P5 approximates ABEC 5, ISO P4 approximates
	ABEC 7 and ISO P2 approximates ABEC 9. Please see our Precision Grades
	table for the exact values of these precision grades. 

	5. What is the purpose of the higher precision bearings ?

	Higher precision bearings are designed to allow high precision machinery
	to operate smoother and sometimes at higher speeds than a standard bearing
	would be capable of. Keeping this in mind, a standard ABEC 1 608ZZ is
	rated with a limiting speed of 32,000 RPM with grease lubrication and
	38,000 RPM with oil lubrication. The actual speed that the bearing will
	attain without failure also depends on the loads applied and other running
	conditions but there is really no need to go into that too heavily here.

	We feel that we must stress here that the purpose of higher precision
	bearings IS NOT TO GO FASTER, but (amongst other things) to ALLOW HIGH
	SPEED MACHINERY TO OPERATE AT FASTER SPEEDS THAN STANDARD BEARINGS WIILL
	ALLOW. PLEASE ALSO READ POINT 6 BELOW.

	6. What will be the result of using these higher grade bearings in
	Skating Applications ?

	The most noticeable result is that you will end up with less money in your
	wallet and the people that sold you the bearings will be eating out at
	restaurants at your expense for a few days. Under the following
	conditions, you may notice an improved performance.

	(a) You spend a lot of money (i.e. thousands of dollars) to have your
	equipment (wheels and board)  redesigned and manufactured to suit these
	high precision bearings. You will need to use some type of shock absorber
	that allows for absolutely no vibration. 

	(b) You will have to be prepared to skate on a perfectly smooth surface
	and make no attempts to use your feet to propel yourself. (Doing so would
	cause shock loads to the bearings and any extra precision would be lost
	very quickly). 

	(c) After you work out how you are going to achieve the above two
	criteria, you may (and that is only "may") experience a better result than
	using ABEC 1 bearings after you attain a speed of about 390 KPH (240 MPH)
	with 65mm wheels and grease lubrication. 

	Similar calculations for different wheel sizes and lubrication methods
	52mm Wheels Grease Lubed Bearings 310 kph (195 mph)
	52mm Wheels Oil Lubed Bearings 370 kph (230 mph)
	65mm Wheels Grease Lubed Bearings 390 kph (240 mph)
	65mm Wheels Oil Lubed Bearings 460 kph (290 mph)
	70mm Wheels Grease Lubed Bearings 420 kph (260 mph)
	70mm Wheels Oil Lubed Bearings 500 kph (310 mph)

	So, what it all comes down to is "do you really think that you need to buy
	these bearing?", "Will Windows 95 do anything for your old XT 1mb RAM
	computer?", "Will you get rich investing in shares if you only have $2.00
	to invest?" - We don't think so.

	7. What are the grades of bearings available in order. How different
	are the grades ?

	OK, but don't forget that you really do not need to waste money on
	anything higher than ABEC 1 or ABEC 3 for skating applications. 

	                                  From Lowest to Highest

	                             ABEC 1 Approximately equal to ISO P0
	                             ABEC 3 Approximately equal to ISO P6
	                             ABEC 5 Approximately equal to ISO P5
	                             ABEC 7 Approximately equal to ISO P4
	                             ABEC 9 Approximately equal to ISO P2

	There are a number of factors covered by the ABEC grades, but to give you
	an idea we will just examine one of these factors - the eccentricity (out
	of roundness) of the track in the inner ring. For an ABEC 1 (lowest grade)
	bearing, the maximum eccentricity allowable is 0.0075 mm (0.000295"). This
	is quite precise - more than precise enough for skates and skateboards. 
	The figure for the other ABEC grades are 0.005 mm (0.000197") for ABEC 3,
	0.0035 mm (0.000138") for ABEC 5, 0.0025 mm (0.000098") for ABEC 7, and
	0.0012 mm (0.000047") for ABEC 9. If used in high precision, high speed
	machinery (see above), these minute variations can make a difference.  The
	fact is that no matter which of these bearings you use in skates or skate
	boards, after 5 - 10 minutes of use the tracks won't just be eccentric,
	they will become irregular (albeit minutely) enough to be practically
	indistinguishable from one another. Your high priced ABEC 9 bearing might
	as well be a 50 cent Taiwanese cheapie.

	8. Are the "Supermarket" ABEC precision bearings really manufactured
	to the correct tolerances?

	We have to believe that they are until it is proven otherwise. If the
	bearings are labelled as ABEC 7 then in most countries the manufacturers
	of the bearings are compelled by law to provide ABEC 7 bearings.  Some of
	the low prices offered for high precision bearings in Supermarkets does
	look a little strange though. Manufacture of high precision bearings is
	not cheap. Our Swiss quality supplier RMB is currently conducting tests on
	a bearing that was purchased at the Supermarket, and labelled as "ABEC 7".
	We will be very interested to see the results of these tests. 

	9. What is the meaning of "Z" and "ZZ" in the bearing code ?

	"Z" is a designation which means a steel shield covering the side of the
	bearing (for most brands). "ZZ"  simply means that the bearing has a
	shield on both sides. Normally, the shield itself will be branded as "608
	Z" even though there is a shield on both sides of the bearing.  This is
	for practicality in manufacturing. It is much more economical to produce
	all of the shields stamped as "608 Z" than it would be to manufacture the
	exact same component with two different stampings on them. Some
	manufacturers supply bearings with removable shields, whilst others have
	shields that are crimped in place. Neither is usually better than the
	other unless you intend replacing the lubricant or cleaning the bearing
	from time to time.

	10. Is there any better sealing arrangements ? Do the seals/shields
	change the bearing quality ?


	The seals have nothing to do with the quality of the bearing, only how
	well the bearing keeps out the dirt and moisture. You could try using a
	non-contact rubber seal. These will keep out the dirt very well and
	shouldn't lose you any speed. You may notice a slight drag if you rotate
	these bearings by hand, but once they are assembled and your weight is on
	the skates this should not create any problem (i.e.; you won't lose any
	speed). Non-contact sealed bearings are not overly expensive, so it won't
	cost you a fortune to trial them.

	11. What is the best way to get more speed out of your bearings ?


	The most significant increase in speed will be obtained by using a quality
	oil lubricant. We are currently trialing a bearing with non contact seals
	and a Teflon Oil Lubricant.  These bearings are currently being used in
	Inline Hockey (Roller Hockey) with some very good initial results. We will
	not be actively promoting them until we are sure that they are successful
	and they definitely won't be sold for astronomical prices. 

	12. Why is there so much hype at the moment about ABEC precision ?

	I have been in the bearing industry since 1984, and the biggest problem
	with the industry is that too many bearing sales people don't know enough
	about the product that they are selling. I have come across people with
	over 20 years experience in the industry who still get scared when a
	customer starts to ask about load ratings, limiting speed, internal
	clearance and yes, you guessed it, ABEC precision. What has happened here
	is that someone has been told a basic fact that higher precision allows
	for higher speed (and this is true under certain conditions). Not fully
	understanding this, the information has spread (mainly by use of the
	Internet) and gained momentum. There are many more inexperienced people in
	the bearing industry than there are experienced people and this has
	allowed for rapid growth of this falsehood.

	13. Some friends have bought ABEC 9 bearings and tell me that it
	definitely increases speed. Why do they believe this ?

	We are not psychologists but we can think of 2 reasons immediately. 
	Firstly, if you had just paid several hundred dollars for a set of
	bearings, you too would "believe" that they were better than what you had
	bought previously for around $30.00 to $40.00. Secondly, and somewhat
	similarly, if you really believe that something will make you faster, it
	probably will (it's all in the mind). 

	14. Somebody recommended that I use Stainless Steel bearings. Is this
	a good idea ?

	Stainless Steel bearings are usually marginally softer than Chrome Steel
	bearings, but this should not matter unless you are an aggressive skater.
	Stainless Steel bearings are advantageous if you are skating in wet
	conditions or close to the sea. They will rust (they are a high carbon
	content stainless steel), but they won't rust as quickly as Chrome Steel
	bearings.

	15. What are the best bearings for Aggressive Skating ?

	Again, you will not get any more life out of either high precision or low
	precision bearings. Aggressive skaters will find that they go through
	bearings more quickly, so the best advice is "Get the cheapest, as long as
	they are a decent bearing".