Relationship between triple rocker blades and toepick

[Query]

I noted in https://skatingforums.com/index.php?topic=8922.msg107565#msg107565 that the JW blades that have 3 rocker radius segments (and 2 sweet spots, by my definition as points where the rocker radius changes), the toepick touches when you are on the forward sweet spot.

With 2 rocker blades, you do not touch the toe pick while on the sweet spot.

This based on profiles at
https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/
and
https://scarletskater.wordpress.com/2017/06/02/blade-profiles/

I assume the blade doesn't sink far into the ice, so the sweet spot is horizontal when you are on it.

So - the forward sweet spot is only used for moves that use the toepick - e.g., scratch spins, 3-turns, etc.

Why is it there? I think you can feel (and hear) the toepick just as easily.

Consequences:

1. To retain this relationship, trim the toepick, or adjust the sweet spot position, when you sharpen your blades.
2. If you adjust the forward sweet spot position, to make it fall below the ball of your foot, you should also adjust the spin rocker radii, to scale them together.
3. You can never skate on the forward spin rocker segment. Exception: high jumps, because you sink into the ice.
4. Proper behavior of these blades is very sensitive to sharpening technique.

[tstop4me]

With 2 rocker blades, you do not touch the toe pick while on the sweet spot.

This holds only if we accept your definition of a sweet spot (a sweet spot is defined as a spot in which the radius of curvature of the blade changes; a blade can have multiple sweet spots; a sweet spot does not depend on the position of the drag pick).  As we've discussed over many years now, there is no consensus on this definition.  You once cited ScarletSkater as an authoritative source, but I pointed out that they provided three different definitions of sweet spot, and you picked the one that agreed with yours.

ETA1:  According to you, with a Coronation Ace blade, after repeated sharpenings, you will need to trim the toepick to extend the service life.  But with an MK Pro blade, you won't need to.  This may make sense to you, but it doesn't to me.

ETA2:  You have created this confusing scenario (confusing even to you) in which some blades have one sweet spot and some blades have two (or more) sweet spots.  If the blade has only one sweet spot, that sweet spot is not correlated with the drag pick.  But if the blade has two sweet spots, the rear sweet spot is not correlated with the drag pick, but the front sweet spot is correlated with the drag pick (which contradicts your basic definition).  And you ask why this is so.  Again, perhaps you should revisit your definition.  Perhaps this confusion doesn't really exist and is an artifact of your own creation.

[Query]

The problem is real, and is not related to terminology.

JW clearly chose to place the front sweet spot - or in your terms, the place where the rocker curvature changes between the two spin rocker zones - so that when you are on it, the toepick touches. Which places the entire front spin rocker section in what some people (e.g., Broadbent) call the "non-skating zone" that normally can't touch the ice, except on jumps. That doesn't change if you call that point something other than what I call it.

And my question was why they did that. They must believe skaters can't feel when the toepick touches, but they can tell when they are on what I call the sweet spot. The thing is, I think feeling that sweet spot is a much more subtle thing than feeling and hearing the toepicking dragging on the ice. So I don't see why it is positioned there. Especially since if you wear or sharpen away even a little of the blade, you can no longer reach that point. Unless you trim the drag pick nearly every time you sharpen. Which no skate tech I know does.

(BTW, as I've mentioned before, I didn't invent the terminology. A skate tech taught me that. But there is no standard terminology that everyone uses - which is why I specified how I was defining it.)

[tstop4me]

The issue is not the terminology per se.  As I discussed before, the issue is what happens when you communicate with others, e.g., coaches and techs.  According to you, there are fundamental differences in the sweet spot(s) of e.g. a Coronation Ace/P99 (what you call a triple rocker blade with two sweet spots) and a MK Pro/Gold Seal (what you call a double rocker blade with one sweet spot).

So if a coach is teaching a scratch spin, and is giving instructions on finding the sweet spot, she now needs to distinguish between blades with one sweet spot and blades with two (or more) sweet spots, including whether or not the drag pick touches the ice depending on the number of sweet spots, and, for blades with two sweet spots, whether she's talking about the front sweet spot or rear sweet spot.

And if a tech needs to decide whether, after a sufficient number of sharpenings, the drag pick needs to be trimmed to maintain the position of the sweet spot, he now needs to distinguish between blades with one sweet spot [no trimming needed] and blades with two (or more) sweet spots [trimming needed].

Well, we have professional coaches and techs on this forum.  I'd like to hear whether any coaches provide different instructions and whether any techs follow different sharpening procedures according to whether the blade has one sweet spot or more than one sweet spot, as you have defined it.

[Query]

It's more complicated than that. Many people call the entire "spin rocker" a "sweet spot". Saying that you should try to spin on the part of the blade somewhere on that definition of sweet spot.

But for a triple rocker blade, you can't spin on the front spin rocker section - i.e., by that definition, the entire "front sweet spot".

AFAICT, for all intents and purposes, except possibly when jumping, the front spin rocker section doesn't exist. And even for jumping, it's usefulness is unclear - perhaps it would be easier to vault over the toe pick if the front spin rocker section was a straight line, more like pole vaulting?

Bill_S said that he took measurements and found that side honing (e.g., parabolic blades) doesn't exist at the level that touches the ice. That it's main effect might be to remove a few grams of weight. I think he more or less seemed to feel that it was merely a marketing ploy a blade company could use to justify the high costs of their blades, but was pointless.

I'm wondering if this is like that. That the presence of the 3rd rocker segment has virtually no effect on skating, once you have removed some metal by sharpening (or by skating a lot). But it helps "justify" the high cost of those blades.

And by the way there are other terminology problems in figure skating. E.g., to many people "rocker" refers not to the curvature radius, but to the single point along the length I call the "sweet spot". Quite a lot of skaters and coaches use that terminology. And you see it a lot on Youtube, and in other videos, that teach figure skating elements.

And others use "rocker" to mean "rocker profile" - the whole shape of the bottom of the blade.

I was really hoping to get some comments on the issue I am talking about - why that spot - which you might prefer me to refer to as "the point along the length of the blade where the rocker profile curvature changes" (so many words! ) - exists, and whether it makes any sense, or is just a marketing ploy.

I admit a lot of people do buy triple rocker blades. But a lot of people buy blades with various forms of side honing too. (And people have told me they feel parabolic blades are much better for landing jumps, in spite of what Bill_s said.) What people buy doesn't always mean they have tested every aspect of what they buy.

[tstop4me]

* As I've written before, in the absence of a standards authority (or authorities) that sets definitions, it's critical that posters define their terms, maintain consistency in those definitions, and follow through the logical consequences (basically, do they make sense).

*

I'm wondering if this is like that. That the presence of the 3rd rocker segment has virtually no effect on skating, once you have removed some metal by sharpening (or by skating a lot). But it helps "justify" the high cost of those blades.

<<Emphasis added>>  Care to provide data to support your contention that 3-rocker blades cost more than 2-rocker blades (following your terminology}?  In the Wilson line, the Gold Seal (2-rocker) costs a lot more than the P99 (3-rocker).  Now this is not a fair comparison, because the Gold Seal has concave side honing and a longitudinally tapered thickness profile, which the P99 does not.  These features add to cost.  But look at the Paramount versions.  The Paramount Gold Seal version does not have concave side honing and tapered thickness.  Paramount has multiple grades of their blades.  At their highest grade, the Gold Seal costs more than the P99.  At their other grades (for which there are comparable models), the prices are the same.  And if you compare the Wilson Coronation Ace (3-rocker) to the MK Pro (2-rocker), the prices are the same. 

[tstop4me]

* So now, it appears you are making a distinction between the non-skating zone of a 3-rocker blade vs. a 2-rocker blade?  My reaction is, "Huh?"

* I'd like to point out that all these complications you've presented result from your definition of a sweet spot and that these complications vanish under a different definition (e.g., the tangent point; see below).

* Again, "the proof of the pudding is in the eating."  Let's hear from the professional coaches and techs on this forum.  How many coaches distinguish between front and rear sweet spots for 3-rocker blades and provide different instructions vs. 2-rocker blades with a single sweet spot?  And how many techs trim/do not trim dragpicks based on whether the blade has 3 rockers vs. 2 rockers?

* Sid Broadbent has a "wellness gauge" for determining when the dragpick should be trimmed (http://www.iceskateology.com/Skateology/Blade_Wellness_Gauge.html).  PBHE has a similar gauge.  These are geared towards HD Sports (Wilson and MK) spin rocker profiles.  Paramount adheres to these profiles, but other companies (such as Ultima and Eclipse) do not.  These gauges do not distinguish between 3-rocker and 2-rocker blades, because they do not depend on "points at which the radius of curvature changes".  They depend on two points:  the tip of the dragpick and the tangent point along the spin rocker [if the blade is oriented vertical to a horizontal reference plane (as if you were skating in a straight line along a sheet of ice), and if you rock the blade forward such that the dragpick just touches the horizontal reference plane, the tangent point is the point along the spin rocker that also touches the horizontal reference plane].  Note: tangent point refers to an idealized geometry; in an actual scenario, there will be a tangent region.

[Query]

Yes, MK and JW blades are in about the same price range, especially since the two companies have merged into HD Sports.

Both are incredibly expensive. I admit MK blades used to be more expensive - but they used to say that at the highest competition levels, most skaters who won medals used MK blades. (Maybe due to marketing campaigns in which MK provided free blades to some high level skaters and coaches, and a few others? But now some JW blades are provided that way too.)

Regardless, it makes sense to add extra fancy features, which may or may not be fully understood by customers that buy them, that make people think the cost of these blades is justified. (Or maybe I just don't appreciate how hard such blades are to make?) Maybe it's like the extremely elaborate curved body shapes on modern cars, which don't have an obvious useful function.

I'm not making a distinction between the non-skating zones of 2 and 3 rocker blades. The manufacturers are. In particular, the entire "spin rocker" section of 2 rocker blades has the same curvature, even the part Broadbent calls the "non-skating zone" because it usually can't touch the ice much if at all. Whereas JW gives that segment a different curvature.

My question was if & how much that matters.

Which you aren't trying to answer, because you are hung up on terminology that I don't really care about.

[Query]

There actually are other conditions in which the forward rocker segment might affect skating.

I have sometimes skated on (shallow artificial) outdoor ice rinks in which the ice was melting on top, or was actually melted. Sometimes the entire blade, and maybe some of the boot, was underwater. (Obviously you would not want to do this on a natural pond that was deep enough to be unsafe if you broke through.)

Under those conditions, maybe the streamlining of the blade would be affected by that part of its shape.

I didn't love skating under those conditions. But some kids enjoyed splashing other skaters with cold water.  I suppose the entire shape of the blade might also affect how good the blade is at splashing. Though - moves resembling hockey stops arguably work best, so I don't know if it would make much difference.