2nd new concept: "critical contact surface" (ice & roller skating)

the "critical contact surface" is the 2nd new concept introduced, as intended & written (2/7/13)
(c.c.s. - conceptual approach, through cross industry knowledge)
it represents the blades'/rollers' minimal total surface area, in full contact with the
skating surface, at a certain moment during skating, beyond which the skater looses.
grip (slips & might fall) and eventually traction (often just partially).

attn: (r.s.) consider replacing the rollers on your skates, right away, if their surface appears
                pitted by craters (mm wide), particularly in speed skating, downhills and/or if you
                are overweight.
                from now on, we will call the rollers, with this type of wear: "pitted"
                (not the same as "pitting" - localized craters on a metal surface, associated always
                with corrosion.)
 the analogy for roller skating (not done 2/7/13), is to be added (using c.c.s.) here below:
 
               

overweight, but want to skate?

first, to all of you, trying to reduce weight this way: respect!
this post is exclusively dedicated to you.
is your body dynamics influenced by overweight? yes.
(here below, comparison overweight/normalweight would be more relevant, if made
between approximately same height & same sex individuals).

how could you avoid skating associated accidents &/or incidents, as much as a normalweight?
simple enough! ex.:
does the kinetic energy (at any given moment) of skaters skating
(overweight and/or normalweight), depend on their body mass & velocity? yes it does.
if your body mass is over your normal value (overweight), for a comparable
kinetic energy (to that of a normalweight), when skating, what would you
control &/or decrease first? (to keep yourself, in the same "risk zone" as a normalweight)
certainly, your speed!
- would you try to skate slower? 
- if you're a skater with a speed addiction, could you become an ex-addict?
  (at least until you reach your normalweight.)

would analogy reveal the unexpected & lead you, to the same outcome, for:
- rotational kinetic (turns, etc.),
- potential (downhills, jumps, etc.),
energies? :)

1st new concept: "secondary play" (ice & roller skating)

"secondary play" is the 1st new concept introduced, as intended & written (2/7/13)
(s.p. - conceptual approach, through cross industry knowledge)
it represents the axial and/or radial play of the:
(i. s.) - grinding wheel, relative to the shaft it is mounted on;
           (could appear when the grinding wheel is/becomes loose, or is fixed/becomes
           decentered, on its rotating shaft; dangerous, as the grinding wheel rotates at high speeds;
           serious injuries may occur, by flying grinding wheel pieces, if this breaks while
           rotating, due to this type of  play; always keep in safe distance  from a sharpening
           machine in operation.
           the grinding wheel's secondary play (axial and/or radial), even taken without any
           abnormal values of the axial and/or radial play of its shaft bearings, could mean damages,
           even beyond repair, to the ice skates' blades.
(r. s.) - rollers, relative to the bearings they are mounted on
            the rollers' secondary play (axial and/or radial), even taken without any abnormal
            values of the axial and/or radial play of  their respective bearings, could mean serious
            crashes, particulary in speed skating, downhill, etc....

bearings' axial and/or radial play, became so much more important in ice & roller skating
competitions, of any kind.

secondary play, as a new concept, for the first time defined, might only add up as information
for the casual skater; but in terms of competition & performance in skating, plays a role & has
to be dealt with, accordingly.