From: adchen@umaxc.weeg.uiowa.edu (Tony Chen)
Subject: REC.SKATE FAQ - part 2/5
Followup-To: rec.skate
Reply-To: adchen@umaxc.weeg.uiowa.edu
Organization: University of Iowa, Iowa City, IA, USA
Date: Tue, 6 Oct 1992 16:46:59 GMT
Expires: Sun, 1 Nov 1992 00:00:00 GMT

Archive-name: rec-skate-faq/part2
Last-modified: 9/11/92

REC.SKATE FAQ - PART 2:  WHEELS, BEARINGS, AND BRAKES (draft)
 
 
                                 Inline Wheels
                                 -------------
                             (written May 17, 1992)
                          (last changed Sept 10, 1992)
 
 
TECHNICAL INFO
 
Inline wheels are made of polyurethane.   Although wheels are classified 
on three criteria: diameter, durometer (hardness), and rebound, you will 
usually see only the diameter and durometer marked on the wheels and/or 
packaging (e.g.,76mm 78A, or 70mm 82A, etc.).
 
 
DIAMETER
 
The diameter of the wheel is basically how tall the wheel is.  The usual
diameters are 80mm, 77mm, 76mm, 72.5mm, 72mm, and 70mm.  More recently, 
82mm wheels have been introduced.  Generally, racing skates will fit up 
to 82mm wheels, high-end skates up to 77mm, and the rest of the models 
up to 72.5mm.  Although these are the designed ranges, skates can take 
slightly taller wheels than what they're supposed to.  For instance, the 
Bauer XF/3's, with the front and heel wheel spacers moved in (for a 
shortened wheelbase), can use 76mm wheels for all four positions.  
Extension modification (i.e., scraping down) of skates are need for 
wheels much larger than the intended size.
 
Although still subject to some technical debate, in general, taller 
wheels will let you go faster (i.e., 76mm are faster than 70mm) but 
there is a point where taller wheels will only make you go slower with 
added weight (harder to start rolling) and less manueverability.
 
Shorter wheels are cheaper, but in general don't last as long since they 
have less material to wear down overall.
 
 
DUROMETER (hardness):
 
Durometer is a relative hardness measure frequently used for rubber and 
plastic products.  There are several scales, with the "A" scale (hence 
the 78A, etc.) used for wheels.  The number is the rating from 0-100, 
with 0 being no resistance and 100 being very hard plastic.
 
Inline wheels generally run from 74A to 93A, with 78A, 82A, and 85A 
being the most common.  For outdoors, the softer the wheel, the better 
the shock absorption on bumps, cracks, pebbles and other vibrations.  
The trade-off is that softer wheels last a shorter time.  Harder wheels, 
since they have less drag, are preferred on indoor surfaces which are 
usually very smooth.
 
Hockey players may prefer harder wheels because it allows them to slide
somewhat.
 
 
Rebound:
This is how much the wheel will return the energy when your wheels are
compressed.  So a higher rebound, will provide more response on each 
stroke.  There doesn't seem to be a rebound scale (is there?) as there 
is for durometer.
 
 
HUBS
 
The hubs are very important to the overall performance of the wheel.  
Hubs which are too large will not hold the bearings tightly enough.  
This can allow the wheel to become "cocked" so that it rubs against the 
frame.  Only one wheel needs to be out of alignment to mess things up.
 
This is a serious problem, not only because it causes drag, but because 
it heats up the wheel which will soon cause it to seperate from the hub 
and expand, which will very soon destroy the wheel.
 
I have noticed this on several sets of Kryptonics Turbocores.  The
first sign is that the wheels creak as you switch your weight on the 
skate. And if you remover the wheel from the frame, there will be a arc 
clear of dirt and dust where the wheel was rubbing.
 
If you notice this, put your hands on your wheels after a long fast 
skate and see if any of them are much warmer than the others.  If so, 
they are probably rubbing.
 
This can happen a lot easier on frames like the Mogema and the Darkstar 
that have very close tolerences and the side of the frame is close to 
the side of the wheel.  I'm not sure if is as big as a problem (or a 
problem at all) for recreational skates like the Areoblade.  But the 
creaking is bothersome in any event.
 
 
AXLE KITS
 
Another important aspect of your wheels is the axles that go with them.  
There are several axle replacement kits (such as the Hyper Hop-up Kit 
and the Blading Edge Kit) designed to let your wheels roll much faster 
than with your stock axles. These kits are usually made of aluminium and 
steel.  What they consist of is two axles per wheel, each screwing into 
the threaded bushing in the wheel. This also prevents overtightening, 
which is common with the regular axle system.  When putting your wheels 
back, make sure the wheels are just snug enough so they don't move 
around.  Anything more just increases the friction on your bearings.
 
 
MAINTENANCE
 
Wheels of any durometer will wear out, given enough mileage.  There's 
only so much polyurethane on your wheels, while there's thousands of 
miles of asphalt out there (a slightly different story for indoor 
skating, but wearage occur nevertheless).  Your wheels are due for 
maintenance when your skates are much  slower and not rolling as 
smoothly as when new.  The inside edges will wear more quickly, which 
you will eventually notice.
 
There are two things to do to increase the life of your wheels:  rotate 
them and flip them.  Rotating your wheels means to switch the positions 
of the wheels.  Different positions (like the heel or toe wheels) 
receive varying amounts of wear.  By rotating the wheels, you can even 
out the wear each wheel receives.
 
Flipping your wheels means to turn each wheel so that the worn edge now 
faces the outside.  This lets you wear down the other portion of the 
wheels.
 
There are several patterns for wheel rotation.  The one you use isn't 
crucial.  The main point is to maintain an even wear on your wheels and 
to extend the amount of mileage you can get.  Feel free to swap wheels 
until you feel you have a good distribution on your skates.
 
Some rotation patterns:
 
The front wheel is "1" and the back wheel is either "4" or "5".
 
For 3-wheel skates:  3->2, 2->1, 1->3
 
For 4-wheel skates:  4<->2, 3<->1                   OR     4->3 3->2 2-
>1 1->4
 
For 5-wheel skates:  5->3, 4->2, 3->1, 2->5, 1->4   OR   5->3, 4->5, 3-
>2, 2->4 
 
In addition to rotating and flipping your wheels, you should also wipe 
off your skates, rails, wheels and bearings with a damp cloth.  This 
keeps the amount of dirt on your skates and wheels to a minimum.
 
 
ROCKERING YOUR SKATES
 
Having skates non-rockered means the axles and wheels are all at the 
same height This is the way the skates come when you buy then.  What 
many skates allow you  to do is to change the height of some or all of 
the axles, to provide a different "blade" to skate on.  Rockered skates 
then, have the middle two wheels lower relative to the front and heel 
wheels.  This is accomplished by having oval spacers with an offset 
axle-hole.  So each spacer can have an up or down position.
 
Racing skates are also adjustable, but only in the horizontal direction,
allowing for a longer or shorter wheelbase.
 
Although subject to some disagreement, many skaters find rockering 
provides much more maneuverability due to the curved "blade" of the 
wheels.  Whether you rocker or not is really up to you.  Many hockey 
players prefer to have their skates rockered for sharper turns on the 
court, while racers keep their blades flat for more stability at high 
speeds (rockers at high speed will produce speed wobble).  Artisitic 
skaters may also prefer rockered, while extreme skaters may 
stay flat.
 
Depending on your skates, there are various rockering configurations 
possible.  If your skates can adjust the height of only the middle two 
wheels, you can have your skates flat or rockered:
 
Flat : ==frame==
 
        1 2 3 4
 
 
Rockered: ==frame==
           1     4
             2 3
 
If your skates can adjust the height of all four wheels then you have
the positions of
 
 
short even rocker: ==frame==    (wheels closer to boot, for more 
control)
                    1      4 
                      2  3 
 
tall even rocker:  ==frame==    (taller, for sharper turns)
 
                    1       4
                      2  3
 
front-lift rocker: ==frame==    (a little more stable than regular 
rocker)
                   1
                      2  3  4
 
front-lift,      : ==frame==    (tilts skates forward)
rear-down, rocker  1
                      2  3
                            4
 
 
 
Wheels generally run from $4.25 to $8.00, depending on the quality and 
size of the wheel.  The three inline wheel manufacturers are Kryptonics, 
Inc. and Hyper Inline and Labeda.
 
 
[Copyright 1992 by Anthony D. Chen.  All rights Reserved.  License is 
hereby granted to republish on electronic or other media for which no 
fees are charged (except for the media used), so long as the text of 
this copyright notice and license are attached intact to any and all 
republished portion or portions.]
 
========================================================================
 
                          THE BEARING MAINTENANCE FILE
                          ----------------------------
                              (written May 2, 1992)
                           (last changed Aug 19, 1992)
                         Compiled and edited by Tony Chen
 
Contents:
* General Info
* Sealed or Shielded?
* Bearing ratings
* How to maintain your bearings
  1st method : If you don't mind taking off the seals.
  2nd method : If you don't want to pry off the seals.
 
 
GENERAL INFO
 
Inline skates all use 608 bearings.  The number means that the bearings
are from the 600 series, with a 8mm inner diameter (the width of the
hole i.e., internal bore).  The "6" appears to be for the 6mm difference 
between the inner and outer radii (from the outside edge to the edge of 
the hole).
 
608 bearings are also the standard size for skateboard bearings.  Quad
skates use either type 608 (8mm internal bore) or type 627 (7mm internal
bore).  The 608s for quads are the outdoor bearings. If your  bearings 
have letters following the "608" (like "S", "Z", or even "ZZ" or "SS") 
it is the manufacturer's way of denoting sealed or perhaps double 
shielded bearings.  To make sure what they mean you should probably
check with the manufacturer, since it varies from company to company.
 
Bearings for in-lines generally come grease filled.  Some bearings like 
GMNs are sold either greased or oiled (but usually greased). 
 
 
SEALED OR SHIELDED?
 
There are basically two types of bearings.  Most likely you will have 
SHIELDED bearings, which most stock skates come with.  Shields will make
it hard for dirt and grime to get in, but they certainly aren't dust or 
water tight.
 
There are also SEALED bearings, which have a teflon or rubber lip seal 
that actually touches the brace, and come packed with a fairly heavy 
grease.  Rollerblade sells sealed bearings under the name Max Trainers.  
You may find other brands as well.  The advantage is that they should 
last a long time without any maintenance at all.  The trade-off is that 
these bearings generally cost more and you also encounter a much higher 
rolling resistance.  Slower bearings are not necessarily bad, since many 
people like the added resistance for a better workout.
 
 
BEARING RATINGS
 
Bearings are rated on the ABEC (the Annular Bearing Engineering Council) 
scale.NMBs are rated ABEC-1, GMNs are ABEC-3, and Powell Swiss and 
Fafnir are ABEC-5.  Buying bearings rated any higher than ABEC-5 will 
probably not do any good since they aren't be meant for use in in-lines.  
The higher precision will be lost to contaminating dust and dirt anyway.  
(If it's speed you want cutting down wind-resistance and improving your 
technique is probably a better way.)
 
Really precise bearings are only used in high speed (read: rotational) 
applications, as in machinery.  The next higher grade up from in-line
bearings are in machines which are rotating at speeds of at least
10,000 rpm which is around 80+ mph.  You probably won't want to go that 
fast on your skates 8-)  At 50,000 rpm you would be traveling 400+ mph.
So which happens first?  the wheels melting, or the skin ripping off the 
skater?  Gives new meaning to shredding 8-)
 
 
WHEN TO CLEAN AND RE-LUBRICATE YOUR BEARINGS
 
Exposure to dirt and water are the main reason that your bearings slow
down.  Bad bearings will be the ones which don't let your wheels spin
for a respectable amount of time.  If you hear or feel the vibrations 
of metal rubbing on metal, chances are, your bearings are in need of 
some maintenance.
 
If some of the balls or bearing surfaces have become roughened, there's
basically nothing you can do.  They won't get any better, but they may 
last a long time anyway.  You can always replace your bearings a few 
at a time.
 
Take care of your bearings by cleaning and preping them as needed.  
Assuming normal usage, they should last through several sets of wheels, 
depending on how much skating you do.
 
 
REPLACING YOUR BEARINGS
 
You can replace your bearings if (1) any of your bearings have somehow 
stopped spinning well, despite all the cleaning you do or (2) you want 
to change to different types of bearings (racing or sealed or whatever).
 
 
HOW TO TAKE CARE OF YOUR BEARINGS
 
1. Remove your wheels from the skates, and push the bearings out with a
   spare bushing (the plastic/metal part that goes between the bearings) 
   or one of the several types of bearing tools available on the market.
 
 
2. If you have Powell Swiss (Bones) bearings, simply pry off the 
   removable plastic cap on each bearing.  If you have NMBs, GMNs 
   (Germans), other shielded bearings, or sealed bearings, carefully 
   puncture or pry off the shield (or seal) on one side. (Some people 
   tell you to never pry off a seal, some say it's okay.  It's really up 
   to you.  Whatever you do, lubrication always helps) 
 
   When removing the covers of entire sets of bearings at once, be 
   careful to only take off one cover per bearing.  Otherwise you'll be 
   left with a shieldless/sealless bearing (which won't last long 
   against outdoor conditions).
 
   Once you have the cover off, you should be able to see the ball 
   bearings inside, held in place by a brace.  You won't need the old 
   metal covers anymore.  In Bones bearings the cap is ALSO the brace, 
   so you won't see a brace.  Bones users should obviously keep the 
   plastic cap when reassembling their bearings.
 
   You don't want to take the ball bearings out since they aren't meant 
   to be removed and replaced.
 
 
3. Soak the bearings in paint thinner, naphtha, Simple Green*, or any
   other handy solvent.  In any case, the choice of solvent isn't 
   crucial so long as you can get all the dirt and old grease cleaned 
   out.
 
   Avoid low-flash point solvents like gasoline, xylene, lacquer 
   thinner, etc. which are dangerously flammable.  Also wear latex/chem 
   lab gloves if possible.  Solvents are no fun to ingest or absorb 
   through your skin.  An alternative is to use a pair of tongs or 
   tweezers to handle your bearings.
 
   How long you soak depends on how dirty and dried out your bearings
   have gotten.  Previously maintained bearings won't need to soak very
   long.  Bearings that have gone dry and have lots of grit in them may 
   need to soak overnight, or even several days.
 
   If necessary use a brush or swirl your bearings around in your 
   container to make sure everything breaks loose.  Small coffee cans, 
   peanut jars, or even the little black film canisters you get with new 
   film, all make decent containers.  You don't really need large 
   amounts of solvent.  Just enough to immerse your bearings.  You also 
   don't need to refill with clean solvent with each bearing, unless the 
   solvent you were using has gotten really dirty.  The essential thing 
   is that the dirt and grease is broken up.  Step 4 will remove most of 
   the gunk.
   
   WD-40 is generally not recommended as a solvent since it leaves a 
   sticky, dust attracting film on the bearings.
 
   *Simple Green.  Just soak the parts in pure Simple Green and rinse 
   with water.  Thoroughly dry everything off and lubricate immediately.  
   Simple Green is water soluble, so take care to dry it well, since it 
   can cause rust otherwise.
 
   Parts come out much cleaner and much faster than with other solvents. 
   You should stay cleaner and there are no nasty fumes to inhale. 
   Simple Green should be available in most grocery or hardware stores.
 
 
4. Now rinse out your bearings with hot, soapy water to make sure you 
   clear out all the solvent.  You now have some clean bearings.
 
   Clean, unlubricated bearings appear to have the lowest amount of 
   unloaded friction, but don't expect them to last very long if you 
   skate on them.   After a fairly short time, the surface of the balls 
   will start to flake   and roughen and they won't spin very well.
 
 
5. Use a hair dryer or just air/sun dry to make sure that all traces of 
   water are gone.  Using a hair dryer or basking in the sun also preps 
   the bearing nicely by heating the metal somewhat.
 
 
6. Now lubricate with your favorite lubricant.  You can use Tri-flow or 
   one of the specialty lubricants distributed for bearings.  Bones 
   bearings come with their own Speed Cream.
 
   You can use grease or oil as you prefer.  Oiled bearings have 
   slightly less resistance, but need to be maintained more often (as 
   often as once a week).  It is very helpful to have a little 
   hypodermic style oiler with a long needle to let you put the oil 
   right where you want it.
 
   Grease works well because after a while most of it gets shoved out of
   contact with the balls and only a little bit smears onto the 
   workings.  However, newly greased (or heavy oil) bearings, will take 
   a while to expel any extra grease and move the rest out of the way.
 
   For oiling, light oil, like sewing machine oil, or 5W-20 motor oil is 
   a good choice.  Household oils (3-in-one, etc) may gum up after a 
   while and the teflon-based lubricants have little particles of teflon 
   that are only in the way.
 
   Some people recommend that you use a 50-50 mixture of lighter fluid 
   and baby oil to lubricate your bearings.  This mix should result in 
   not having to clean them out as often, only lubricate more often.
 
   Let the bearings sit for an hour, and wipe them off.
 
 
7. Put one bearing back into the  wheel, with the open face towards the 
   inside of the wheel.  Insert the bushing and then put on the second 
   bearing (with the open face towards the inside again).  It is pretty 
   hard for contaminants to get into the bearings from the inside.
 
 
2ND METHOD (for keeping the shields on):
 
   First do Step 1 (from 1st Method).
 
   If your bearings are permanently sealed (or you don't want to remove
   the seals) you can still soak in solvent (see step 3) for several 
   hours or as long as you feel necessary.  Enough solvent should soak 
   through to remove some of the grease.
 
   Then you can lubricate the seams and/or press some in with your 
   fingers.  Enough oil should seep through to lubricate your bearings 
   (see step 6).
 
========================================================================
 
 
From: pae@netwise.com (Phil Earnhardt)
Date: 8 Mar 92 04:03:01 GMT
 
First off, note that there are 3 types of brakes available for the Rollerblade
"square" brakes (used on current Rollerblade high-end skates -- Lightning,
Aeroblade, Racerblade, etc.):
 
	o Black Brakes. What used to come on the skates by default; what
	  dealers stock as replacement brakes by default. Marking and squeaky.
	o TRS Brakes. They gray guys. About twice as expensive. Marking.
	  Somewhat squeaky, but less than the black ones.
	o Polyurethane Brakes. These appeared near the end of the summer of
	  1991. They come in bright blue, pink, green. Priced near the price
	  of the TRS Brakes. No squeako at all (sometimes, they hum -- it's
	  kind of nice). No marking at all. By my metric, they last longer
	  than the Black guys but not quite as long as the TRS Brakes. The
	  braking action is a bit grabby; some may view this as a problem.
 
WRT brake life, I'm sure you'll get some subjective opinions. However, I have
never observed the Poly brakes crumbling and coming off in chunks. Remember,
the wheels are just polyurethane, too -- do you see them come off in chunks?
It might be possible to lose chunks of polyurethane on extremely rough roads;
I'd recommend avoiding such surfaces.