Posted-By: auto-faq 3.1.1.2
Archive-name: rec-skate-faq/part2


   Rec.skate Frequently Asked Questions Part 2
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                                 REC.SKATE FAQ
                                       
Part 2: Wheels, Bearings, and Brakes

   
   
  TABLE OF CONTENTS
     * Inline Wheels
     * The Bearing Maintenance File
       
   
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Inline Wheels

   (written May 17, 1992)
   (last changed July 19, 1993)
   
  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
   (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. Also new are short stunt
   wheels, 52mm in diameter, with a high durometer to allow for rail
   slides and other tricks.
   
   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.
   
   Misalignment is a serious problem, not only because it causes drag,
   but because it heats up the wheel. This will soon cause it to seperate
   from the hub and expand, and eventually destroy the wheel.
   
   I have noticed this on several sets of Kryptonics Turbo-cores. The
   first sign is that the wheels creak as you switch your weight on the
   skate. If you remove the wheel from the frame, you can see an 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 Aeroblade. The
   creaking is bothersome in any event.
   
  AXLE KITS
  
   Another important aspect of your wheels is the axles. There are
   several axle replacement/upgradd kits (such as the Hyper Hop-up Kit
   and the Blading Edge Kit) designed to let your wheels roll much faster
   than your stock axles will allow. 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. Much less wearage occurs for indoor
   skating, however.
   
   In general, 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:
   

               |    |                         |    |
       inside  |    |  outside       inside   \    |   outside
        edge   |    |    edge         edge     \   |     edge
               \____/                           \__/

              new wheel                       worn wheel

   There are two things you can do to get the most from your wheels:
   rotate and flip. 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 on each wheel.
   
   Flipping your wheels means to turn each wheel so that the worn edge
   now faces the outside. This lets you wear down the other edge of the
   wheels.
   
   There are several patterns for wheel rotation. The one you use isn't
   crucial, since there's no "magic" rotation formula that works for all
   situations. The main point is to maintain an even wear on your wheels.
   Often times you may find yourself swapping wheels at random until you
   get a good wearage distribution on your skates.
   
   Some common 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:  42, 31     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

   Whiled you're rotating and flipping your wheels, you might as well
   wipe off your skates, rails, wheels and bearings with a damp cloth.
   Some people wipe down their skates everytime they go out, even if they
   don't do any rotation, but I recommend you do it at least everytime
   you rotate your wheels. This keeps the amount of dirt on your skates
   and wheels to a minimum, which helps keeps grit out of your bearings.
   
  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
   (usually). 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; 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 opt to
   keep them 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 main inline wheel manufacturers are
   Kryptonics, Inc. and Hyper Inline and Labeda.
   
   
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The Bearing Maintenance File

   (written May 2, 1992)
   (last changed July 19, 1993)
   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 "608"r 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.
   
   A little cross-reference on part numbers for bearings, the 7MM ones
   are for quality indoor skates, the 8MM ones are used for in-lines,
   other indoor skates and skateboards.
   

Double Shielded:
        NTN     Fafnir  MRC     ND      SKF     HCH     YW
7MM     627-ZZ  37KDD   37FF    77037   R7-2Z   627Z    60027
8MM     608-ZZ  38KDD   38FF    77038   R8-2Z

Double Sealed (neoprene rubber):
        NTN     Fafnir  MRC     ND      SKF
7MM     627-LL  37PP    37ZZ    99037   R7-2RS
8MM     608-LL  38PP    38ZZ    99038   R8-2RS

   Single shielded/sealed bearings usually delete one of the doubled
   prefix/suffix characters. (Thanks go to George for the above chart).
   
   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: shielded vs sealed. Most
   likely you will have shielded bearings, which all stock skates come
   with (as far as I know). Shields make it hard for dirt and grime to
   get in, but they certainly aren't dust or watertight. For superior
   protection against the elemnts, you need sealed bearings.
   
   There are three kinds of shielded bearings: 1) two shields (metal), 2)
   one metal shield & one pop-out cap for maintanence, 3) two pop-out
   caps. If you have types 2 or 3, you'll have an easier time re-lubing
   your bearings (see below)
   
   Sealed bearings have a teflon or rubber lip seal that actually touches
   the brace and come packed with a fairly heavy grease. These are quite
   impervious to dust or water. 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. The main brands are NMBs (stock ABEC-1 bearings),
   Powell Swiss (ABEC-1), GMNs (ABEC-3), Fafnirs (ABEC-5) and Black-Hole
   (various ABECs). 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 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 ones which don't let your wheels spin
   for a respectable amount of time (the definition of "respectable"
   depends on on your type of bearings). 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
  
    1st Method: Taking the shields off
    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 shielded bearings with pop-out caps (Powell Swiss or
       Black Hole brands), simply pry off the plastic cap on each
       bearing. If you have NMBs, GMNs (Germans), other brands, or sealed
       bearings, FIRST make this decision: do you want to take the
       shields off?
       
       Some people tell you to never pry off a shield/seal, some say it's
       okay. It's really up to you. Whatever you do, lubrication always
       helps.
       
     NOTE: if you have sealed bearings you might not want to pop the
     covers since you'll ruin the seal integrity somewhat, which is what
     you're paying extra (vs regular bearings) for in the first place.
     However, if you feel they've gotten dirty enough, try relubing just
     a single bearing and see if it's any better. If so, re-lube the rest
     of your bearings.
   
       
       If you decide no then skip down to the section marked 2nd Method.
       
       If you decide yes then carefully puncture or pry off the shield
       (or seal) on one side.
       
       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.
       
       NOTE: 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. Handy tip: if you're using Simple Green, use it in the
       concentrated form, and also heat it up. This will speed up your
       cleaning time significantly.
       
       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 those little black film canisters, 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.
       
       Ultrasonic cleaners is ideal for cleaning bearings. If you have
       access to one, you can clean your bearings en mass and avoid
       getting your hands dirty.
       
       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. 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: 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).
   
   
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