Location of blade on sole

[Christy]

I recently read about someone having their blades fitted to their boots based on their foot position within the boot, which meant that the blade was set back a bit from the front of the boot, so a couple of mm from the tip. My fitter has always insisted that the blade absolutely must be at the very front of the sole which sometimes means a small gap at the heel. Like so many people one of me feet is shorter than the other and I struggle to find the rocker at times, I was wondering if I should have the blade(s) mounted a small way back on the sole?

[tstop4me]

I've done so in the past for my own boots and blades.  That is, just as you can move the blade inside/outside to find the best position for your foot, you can also move the blade front/back. 

[Query]

Back when Klingbeil was in business, Don Klingbeil (or maybe it was a Klingbeil factory rep - this was a long time ago) told me that on a well fit full custom boot (i.e., the size and shape of the boot are designed for the foot, including the position, size, and shape of the outsole), the outsole would correctly show the correct mounting position for the blades. Presumably, not because the outsole determines proper position of the blade, but because if it is fit right, the outsole will be sized, shaped, and positioned correctly.

Unfortunately, not everyone gets well fit full custom boots. If you don't have that, there is no reason your outsole should determine proper mounting position.

Think about it: if you use stock boots, or only slightly customized boots, you probably chose the length and width of your boots as something of a compromise, because your feet didn't exactly match the boot shapes.

BTW, not everyone agrees with that. And in fact, if you offset your blade too much to the left or right, then, depending on how your boot is constructed, it may warp or twist the boot in an undesirable way. I suppose that in extreme cases offsetting it too far forwards or back could do the same thing.

Mike Cunningham, who was a quite well regarded skate tech, once told me that if he mounted the blades much too far forwards or back, other skate techs would claim he had done it wrong, so he would hesitate to do go to extremes.

But for the most part, many of us have decided that small changes in position from those that are nominal are OK, if they work better with our bodies. And some of us think that even the length of the blade should have as much to do with your foot anatomy (projected vertically, because most boots enforce a forwards tilt and bend of your feet) as with boot size and shape.

But of course, you can make your own decisions on such things. I think people shouldn't be afraid to experiment to determine what works best for them.

[AlbaNY]

I'll echo what Query and Tstop wrote. 

However, my personal opinion (influenced by my main coach and now by personal experience) is that we tend to geek out far too much about equipment and sharpenings and can adapt very well.

[tstop4me]

Mike Cunningham, who was a quite well regarded skate tech, once told me that if he mounted the blades much too far forwards or back, other skate techs would claim he had done it wrong, so he would hesitate to do go to extremes.

I find that surprising.  If a master tech knows that an extra-ordinary mount would be appropriate to compensate for an extra-ordinary foot condition (for example), then I would hope he would go though with it.  A master tech who has confidence in his superior skills wouldn't care what other techs, with inferior skills, would think.  The proof would lie in the success of the end result:  how satisfied is the customer?

[tstop4me]

However, my personal opinion (influenced by my main coach and now by personal experience) is that we tend to geek out far too much about equipment and sharpenings and can adapt very well.

I agree that really good skaters can adapt to less than optimum equipment.  But for many skaters, some seemingly minor tweaks can save a lot of grief.

I'm not a professional skate tech, but I do help out some skaters that I'm friends with.  E.g., moving the blade a couple of mm, adding a set of shims, or installing custom tongue liners resolved long-standing issues for several skaters (advanced freestyle and advanced ice dance).  And I made a whole bunch of skaters who were constantly having lacing problems really happy when I swapped out their laces and changed their lacing pattern.   One skater was about to write off a new pair of ~$700 boots that she just couldn't get to work right, despite multiple tweaks by her tech; she was ecstatic when I solved her problem with different laces and a different lacing pattern .

[Kaitsu]

Its common here in Europe that blade is positioned 2-3mm backwards. However this is valid mostly to Gold Seal, MK Phantom and Matrix Supreme blades. Usually instruction for this "trick" comes from the coach whom wants skater(s) to roll easier to the toe picks. Many times Russian coaches likes this "trick".

I have never heard that wish to this "special" blade positioning would come from the skater. Not even all coaches does not understand why blade is moved a bit backwards. Before you go shopping new boots / blades, it is very important to know beforehand how blade is going to be positioned. Many times blade needs to be slightly shorter, if you move it 3mm. Wish to have shorter blade is another thing why blade might be moved backwards. Its some kind of trend here that people want to have shorter blades than in the past.

Reason why "special" blade position is done mainly to the mentioned blade models relates to the lowest toe picks positioning. If you compare example Ace and Gold Seal lowest pick position to the toe plate, you start to understand the reasons. This is something which is not told in anywhere. I have learn it by measuring / comparing different blades. You can learn quite a lot from the blades just by measuring them. Many videos what I made are giving tips where to focus...if you are interested to get technically best blades and not just nice promotional words.

[Query]

Interesting points, Kaitsu. It is very helpful that you explain this effect of moving the blade back, so she can decide whether she wants it.

It would also move back the sweet spot, which is what I was told to call the point(s) near the front of the blade where it transitions between the main rocker curvature, and the more curved "spin rocker" curvature - point(s) where many skaters try to balance, because it is a reference point they can feel, especially when doing turns or spins, and which many people feel works best when it is directly underneath the ball of their foot. Changing the spin rocker position is not particularly difficult for a knowledgeable skate tech, but some skate techs don't understand how to do it. (All or most MK Blades, and last I knew Ultima blades, have one sweet spot; I think most JW blades have two, so that there are 3 lengths of the blade with different rockers instead of 2. I still don't know why JW does that - maybe some people spin and turn on different spots, or use the 2 spots for different types of turn??)

I suppose those of us who sometimes touch the back toe pick (sometimes called the "drag pick") when we don't want to could do the exact opposite - move the blade a bit forwards of the front of the mounting plate.

Of course, if we moved it too far, we would need a bit longer blade, so the back end of the blade wouldn't drag. And once again, it would change the sweet spot position.

And of course, an alternative way to make someone touch the toe pick less often would be to trim the drag pick - which would not adjust the sweet spot.

[AlbaNY]

I agree that really good skaters can adapt to less than optimum equipment.  But for many skaters, some seemingly minor tweaks can save a lot of grief.

I'm not a professional skate tech, but I do help out some skaters that I'm friends with.  E.g., moving the blade a couple of mm, adding a set of shims, or installing custom tongue liners resolved long-standing issues for several skaters (advanced freestyle and advanced ice dance).  And I made a whole bunch of skaters who were constantly having lacing problems really happy when I swapped out their laces and changed their lacing pattern.   One skater was about to write off a new pair of ~$700 boots that she just couldn't get to work right, despite multiple tweaks by her tech; she was ecstatic when I solved her problem with different laces and a different lacing pattern .

Perhaps I should be more forgiving of what small changes can do then. 

[tstop4me]

...

It would also move back the sweet spot, which is what I was told to call the point(s) near the front of the blade where it transitions between the main rocker curvature, and the more curved "spin rocker" curvature - point(s) where many skaters try to balance, because it is a reference point they can feel, especially when doing turns or spins, and which many people feel works best when it is directly underneath the ball of their foot. Changing the spin rocker position is not particularly difficult for a knowledgeable skate tech, but some skate techs don't understand how to do it. (All or most MK Blades, and last I knew Ultima blades, have one sweet spot; I think most JW blades have two, so that there are 3 lengths of the blade with different rockers instead of 2. I still don't know why JW does that - maybe some people spin and turn on different spots, or use the 2 spots for different types of turn??)

I suppose those of us who sometimes touch the back toe pick (sometimes called the "drag pick") when we don't want to could do the exact opposite - move the blade a bit forwards of the front of the mounting plate.

Of course, if we moved it too far, we would need a bit longer blade, so the back end of the blade wouldn't drag. And once again, it would change the sweet spot position.

And of course, an alternative way to make someone touch the toe pick less often would be to trim the drag pick - which would not adjust the sweet spot.

(Emphasis Added)

I'll refer you to a thread from 2019:  http://skatingforums.com/index.php?topic=8433.msg100726#msg100726  Reply#6 on.

I cautioned you then that your peculiar definition of "sweet spot(s)" would likely lead to confusion in discussions with coaches and techs.  Your response at the time was that you weren't taking lessons and you did your own sharpening; hence, no opportunity for confusion.  But it appears to me from the above that your peculiar definition is causing confusion for yourself; hence, perhaps you should re-examine whether that peculiar definition has value.

[Query]

We are going way off topic.

But you are oversimplifying my response.

My definition of sweet spot was taken from a particular skate tech that I respected. And I have found that definition mentioned a few other places - though it is possible they took it from me or that skate tech, or from someone who took it from me or that skate tech.

And it's not that I never took lessons. For a fair number of years, I took two lessons a week - one from an ice dance coach, one from a freestyle coach. And for some number of years, I used commercial skate techs to sharpen my blades, none of whom were confused by the terminology I use. The absence of a standardized terminology means that many good skate techs work to clarify what the customer wants, at least in those shops where the skate tech talks to the customer, which, for the most part, were the only places I chose to go.

A "sweet spot" in normal lingo usually refers to an optimum point or optimal form - e.g., an optimal form for achieving an athletic goal. It's not clear what the point your definition is optimal for - e.g., it creates a lot of extra drag to spin on that point. OTOH, my definition could arguably be considered a fairly optimal point for spins, because a good skater (not me!) can feel when they are there, and can therefore stably maintain.

[Kaitsu]

(All or most MK Blades, and last I knew Ultima blades, have one sweet spot; I think most JW blades have two, so that there are 3 lengths of the blade with different rockers instead of 2. I still don't know why JW does that - maybe some people spin and turn on different spots, or use the 2 spots for different types of turn??)

Are you kidding us?

[Query]

Are you kidding us?

No.

I think the maintenance - and the placement of what I am calling the sweet spot (and tstop4me refers to as a transition point) is one of the more important skills that delineates the very best skate techs.

I admit that there are a some good skaters who can compensate for failure to do so - just as there are some skaters who can compensate for uneven edges, dull blades, and somewhat rounded off backs of blades. But they shouldn't have to.

I wish blade manufacturers sent all the pro shops clear written directions and perhaps videos on how to sharpen and adjust blades in the best possible ways, and provided them templates of the nominal blade shapes. MK sold blade profile templates decades ago, but for some reason they stopped. I've sometimes seen blade profiles on Paramount's website, like the attached image (which BTW, claims the MK Phantom has 3 rocker lengths, and Gold Seal has 2, contrary to what I was told about their blades - but I'm not sure how authoritative Paramount is on other people's blades), but AFAIK, they have never bothered to explain the benefits of the different profiles, or how a skate tech might want to modify them for a given skater. I've heard different theories about that sort of thing from different skate techs.

[Query]

BTW, here are a few other blade profile pictures:

https://scarletskater.wordpress.com/2017/06/02/blade-profiles/

and

https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/

Notice that ScarletSkater initially defines the "sweet spot" as where the rocker curvature changes, like me, but indicates that it is the same as as tstop4me's definition too.

She does indicate that different spins should use different sweet spots, and in one case she says the entire middle of three different rocker curvature lengths is to be called the "sweet spot".

And she does have definite preferences, as to what profiles for blades are best for spinning and jumping.

[Kaitsu]

When our daughter started figure skating, girls compared each other's blades. They counted the number of spikes in the toe picks. The number of spikes determined whether the blades are jump blades or not and what kind of jumps the blades are suitable for. I didn't know that, but luckily I learned that from them.

Query,
As I would like to belong to very best skate techs category, could you teach us by sketching to the picture you shared, locations where the sweet spot(s) locates on each blade type?
I can see that used terminologies and definitions are now causing some confusions. Picture tells us more than thousand words, so sketched picture please. I am aware of Scarletskater pictures, so I am interested about the picture you have sketched, not the existing pictures.

[tstop4me]

https://scarletskater.wordpress.com/2017/06/02/blade-profiles/

and

https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/

Notice that ScarletSkater initially defines the "sweet spot" as where the rocker curvature changes, like me, but indicates that it is the same as as tstop4me's definition too.

She does indicate that different spins should use different sweet spots, and in one case she says the entire middle of three different rocker curvature lengths is to be called the "sweet spot".

* Those are not my take-aways.  One writer.  Two articles.  Different definition of "sweet spot" in each.  A sure-fire red flag calling for closer scrutiny of content.

* From https://scarletskater.wordpress.com/2017/06/02/blade-profiles/.

"The "sweet" spot is the ideal part of the blade to spin and perform three turns on. This starts where the curvature of the main (glide) rocker changes, indicating the beginning of the spin rocker, and ends where the blade cannot rock any further as the drag pick comes into contact with the ice."

Very puzzling wording.  This states that the sweet spot corresponds to the entirety of the spin rocker.  Huh?  In which case, why not just refer to the spin rocker, instead of cooking up the term "sweet spot"?

The very next paragraph following the one above, however, contradicts the definition just given, and limits the sweet spot to the following region of the spin rocker:

"Next time you step on the ice in a pair of skates, stand still and rock your foot forward until the drag pick hits the ice (you can't skate on the curved part of the blade immediately behind the toe pick). Then slowly move your foot back until the drag pick is barely contacting the ice. This is the general location of the "sweet" spot. It should feel very slick with little to no friction if you move your foot side to side. How that spot translate directly to where you are pressing through your foot will vary person to person, but ideally should fall on the forward portion of the ball of your foot."

That's more like it.

(cont'd below)

[tstop4me]

(cont'd from above)

* From https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/.

"Blade profile is the shape and placement of the spin rocker in relation to the rest of the blade. The point where the curvature of the rocker changes is the 'sweet spot'. This point should fall just slightly forwards of the ball of your feet (where it bends). Hence, blades are designed to accommodate people's foot differences in boots."

This is similar to the definition you use, but with a critical distinction.  Based on previous text, "rocker" refers to the main rocker.  Therefore, the sweet spot is the point where the curvature of the blade changes from the curvature of the main rocker to the curvature of the spin rocker, as shown in a drawing.  Note that the article does show examples of blades with spin rockers having a single radius of curvature and blades with spin rockers having two radii of curvature.  But the writer never explicitly calls out that each and every point in which the radius of curvature changes corresponds to a distinct sweet spot.  And the writer never explicitly calls out that blades with spin rockers having two radii of curvature have two sweet spots.

Overall, we have somewhat muddled descriptions with three definitions of "sweet spot".  Doesn't provide much clarity.

[Query]

"The "sweet" spot is the ideal part of the blade to spin and perform three turns on. This starts where the curvature of the main (glide) rocker changes, indicating the beginning of the spin rocker, and ends where the blade cannot rock any further as the drag pick comes into contact with the ice."

Very puzzling wording.  This states that the sweet spot corresponds to the entirety of the spin rocker.  Huh?  In which case, why not just refer to the spin rocker, instead of cooking up the term "sweet spot"?

You can interpret what she said differently. Namely, the length beginning where my "sweet spot" is, and ending where yours is.

Also, note that in one of her pictures, there is one main rocker, and two spin rockers - and the entire middle length - the less curved spin rocker - is called the sweet spot.

My simple interpretation is that different people have used different definitions of "sweet spot" with her - and she wrote different articles, or different parts of the same article, at different times, using different definitions.

I guess you could simply decided not to use such a poorly standardized term. But a lot of terms that people use often are imperfectly standardized. For example, some people use her definition of "tapered", but some use one that is exactly opposite hers. Again, there are a lot of different definitions of "side honing". Even "hollow" - e.g., a hollow ground knife typically has a hollow ground into the sides (a type of side honing), not the bottom.

I bet if you think of it, there are terms that people use in engineering, that different people define differently. And in an introductory textbook written by a committee, I bet you will find that different sections often use contradictory definitions. That's extremely common in other fields too. There is a tendency for each level of more advanced text book to try to correct the mistakes or imprecisely worded explanations or inconsistencies of the prior level textbook.


BTW, a lot of people have had links to ScarletSkater's posts. So they must think what she says is worth reading.

[tstop4me]

Aircraft Mechanic 1:  "The instructions say to install the "door plug" over the "optional exit".  But the instructions have three definitions of "door plug" and two definitions of "optional exit".  Could you help?"

Aircraft Mechanic II (reads through the instructions, and replies):  "Well, I interpret the "door plug" to be this unit here (points to a panel), and I interpret the "optional exit" to be this hole here (points to an opening in the fuselage)."

Aircraft Mechanic I:  "Gee, thanks.  ....  Hey I found this bag of bolts on the floor.  Know what they're for?"

Aircraft Mechanic II (looks through the instructions again):  "Don't see any mention of them in the instructions.  Someone on the night shift must have left them here."

Aircraft Mechanic I:  "OK.  I'll leave them where I found them, in case someone comes back looking for them."

[Kaitsu]

Query,
I am still waiting your  own interpret to the sweet spot. Kindly share your own opinion in picture format, like I requested earlier. I would like to understand better your  interpret where single spinning rocker radius means single sweet spot and two spinning rocker radius's two separate sweet spots. I am interested just and only of your own interpret in picture format, not your refer to what is said somewhere else. This should be very easy task.

[tstop4me]

I guess you could simply decided not to use such a poorly standardized term. But a lot of terms that people use often are imperfectly standardized. For example, some people use her definition of "tapered", but some use one that is exactly opposite hers. Again, there are a lot of different definitions of "side honing". Even "hollow" - e.g., a hollow ground knife typically has a hollow ground into the sides (a type of side honing), not the bottom.

Terminology depends on the specific field of application.  E.g., "cell" has completely different meanings depending on whether you're a biologist, a crystallographer, a telcom engineer, or a criminologist.  On a more limited range, a knife blade (one edge) is still a substantially different application from a figure skate blade (two edges).  Why would you expect the term "hollow ground" in knife manufacturing to be at all relevant to "hollow" in figure skate sharpening?  What about the hollow tree in which elves bake Keebler cookies?

In the absence of industry-wide standardized terminology, it's also not surprising that different people within the same field of application would use different terms to refer to the same thing or use the same term to refer to different things.  E.g., Wilson uses the term "tapered" to refer to a blade in which the thickness decreases linearly from toe to heel.  But Ultima uses the term "tapered" to refer to a dovetailed edge.  That's OK as long as they both define what they mean by the term and use it consistently within their product lines.  BUT it would be inane for a single manufacturer to use "tapered" to refer to a variable thickness in Model A blade and to edge geometry in Model B blade.

Back to Scarlet Skater.  If you were to follow their guidance and align the sweet spot with the ball of the foot, which sweet spot would you align?  The one nearest the front of the spin rocker?  The one nearest the rear of the spin rocker?  Or one in between?  This is the practical consequence.

[Query]

Kaitsu: I am not good at drawing pictures. My interpretation is that the sweet spot is a single point along the profile = the front of the main rocker, the back of the spin rocker. And that point is what I like to align vertically with the center of the ball of the foot, or a little forwards of that.

I can think of lots of cases of inconsistently defined terms in the fields I worked in. E.g., "Resolution" in image processing, also called "optical resolution", was the closest distance that two small objects could be told apart apart. But it often means the number of horizontal and vertical pixels.

In various physics texts, "half life" has somewhat different definitions.

"Artificial intelligence" is a buzzword with a lot of currency. But it refers to many quite distinct methodologies, many of which did not used to be considered AI - e.g., the use of correlation coefficients and Bayesian probabilities. Or any other algorithm which a human has created - that didn't used to be considered (in image processing) to be AI. It used to be that "AI" involved things like neural networks, or simulated neural networks, or other particular classes of poorly controlled and understood machine learning algorithms. Given the wide range of ambiguous usage, I find politicians' and lawyers' attempts to regulate "AI" comical at best, and dangerous at worst.

"Latitude" and "Longitude" are defined within the context of multiple systems and assumptions. It can be quite critical that you use consistent systems and assumptions - e.g., use the wrong one and you might easily be off by as much as about 1/2 kilometer. Getting it right can be the difference between having a fun recreational trip, and being arrested and tortured to death as a spy.

And so on.

[tstop4me]

"Latitude" and "Longitude" are defined within the context of multiple systems and assumptions. It can be quite critical that you use consistent systems and assumptions - e.g., use the wrong one and you might easily be off by as much as about 1/2 kilometer. Getting it right can be the difference between having a fun recreational trip, and being arrested and tortured to death as a spy.

This is precisely the point I've been emphasizing.  In a document, or set of related documents, writers need to define the terms they are using (if the terms are not well established) and then use those definitions consistently:  they should not change the definitions willy-nilly. 

[Christy]

Have to say I'm a bit confused by some of the responses as the thread seems to have got a bit off track.

I was thinking that moving the blade back would help to ensure the rocker is in the correct position under the foot, and that is the main reason why it could be beneficial? I suppose it does mean the toe pick location relative to the foot changes too, but not sure that has as much impact as the the rocker location?

[tstop4me]

Have to say I'm a bit confused by some of the responses as the thread seems to have got a bit off track.

I was thinking that moving the blade back would help to ensure the rocker is in the correct position under the foot, and that is the main reason why it could be beneficial? I suppose it does mean the toe pick location relative to the foot changes too, but not sure that has as much impact as the the rocker location?

I'll give you a simplified perspective.  If you want to play around with your equipment, there's no harm in doing so, as long as the changes you make can be readily undone.  So if you simply want to change the placement or orientation of your blade relative to the boot for whatever reason, go ahead and try it.  It doesn't matter what you define as the rocker, sweet spot, or anything else.

Depending on how close the new mounting holes are to the old mounting holes, you might need to plug the old holes first.  If the new mount doesn't work out, again you might need to plug a set of existing holes before drilling new ones.  I highly recommend permanent plugs cemented in with suitable adhesive, not simply pounded in.

On the other hand, I'd be really, really leery of changes such as:

And of course, an alternative way to make someone touch the toe pick less often would be to trim the drag pick - which would not adjust the sweet spot.

Once you've trimmed the drag pick, it can't be readily undone (in the event that what you consider to be the sweet spot does depend on the height of the drag pick; or in the event that the height of the drag pick affects something else).