Right Hollow - Debunking a Myth

[Holden Caulfield 5]

Hi:

The internet is full of forum posts and articles stating that a skater's optimal hollow has an inverse relationship with the skater's weight. In other words, when choosing a hollow, deeper hollows are often recommended for lighter players and shallower hollows are often recommended for heavier players. The rationale given for this guidance is that heavier players cut deeper into the ice and therefore will not require as much bite when turning and stopping.

Interestingly, I have never seen anyone bring up the fact that a heavier player creates significantly greater centrifugual force (F=MA) when turning which requires greater bite to overcome. This fact contradicts the premise above - that a heavier player requires a shallower hollow and a lighter player requires a deeper hollow.

Has the bite force, by weight, a hollow delivers ever been scientifically evaluated against the centrifugal force a skater generates?

I think the guiding principle is a myth without any scientific basis that has just snowballed through supporting what someone else said without questioning why. And, more importantly, providing this guidance is a diservice to new skaters who would benefit from a shallower hollow's greater glide while still retaining equivalent cornering speed through the use of edge control.

.

Just want to put in question a hollow guiding principle that affects us all.

Regards,

Holden Caulfield

[interpathway 9]

Great handle HC. I think it has 'stuck' because it gives heavier or lighter players a ruler to judge from. No one offers me suggestion as to what hollow I want put on my skates because those who have been playing long enough have found their own perfect set-up.

Only those who haven't are the ones asking around for one-size-fits-all advice around the LHS. "Well you're pretty light, why don't we try a sharper cut for you".

The 'heavier-shallower lighter-deeper' idea IMO is nothing more than a general guideline, perhaps only applicable to those brand new to the sport.

[JR Boucicaut 3759]

In my (and other knowledgeable sharpeners) defense, we've never used the word "required," however there are sharpeners who determine a hollow on that basis alone. Just today I recommend to a skater in a thread to gradually move from his hollow until he pushed the limits on one end of the spectrum, and then to dial it back.

It is merely a starting point, just like a measuring gauge on skates. Weight does play a factor, as do ice conditions, blade thickness, blade radius, blade height, skater's ability and personal preferences when it comes to choosing a hollow. However, there will always be a tradeoff between bite and glide.

[Law Goalie 147]

What's missing is the other half of the traditional ROH rationale: that a heavier player, in pushing the blade deeper into the ice, will have noticeably more drag in gliding than a lighter player at the same ROH. This is exactly what FBV addresses, by reducing drag in glides; it's generally been observed that bigger players benefit proportionally more from FBV's advantages.

You're also being a bit sophistical in your suggestion that the greater force of a larger player at the same speed as a smaller player requires more 'bite' to counteract his momentum. On the contrary: he needs *less* bite, or he'll brak his ankles or flip head over heels -- which is what happened to me, thankfully, the first time I threw a hockey-stop at full speed wearing goalie skates sharpened to 7/16" in my pre-FBV days.

That a heavier player requires a shallower hollow is not, as you say, a 'premise': it's a conclusion based on general observations about drag in glide, which only different blade geometry can change, and, secondarily, too much and too sudden forces in stopping and turning, which can be overcome with technique and strength to a degree.

And, as JR points out, there are myriad other factors involved.

In short, I have the same problems with your arguments as I do with the narrative from you which drew your name. (Ducks eggs.)

[forbs02 20]

Skater ability needs to be added into this. A skater may feel their skate doesn't have a deep enough hollow because it isn't biting they way they think it should. In reality they are not utilizing their edges correctly.

My own preference is to put a skater into the shallowest hollow they feel comfortable with. I don't have deeper than an 1/2" hollow on my team, half of the team is in 5/8" or lower. Player weights range from 140 lbs. to 190 lbs.

[wrangler 157]

Hi:

The internet is full of forum posts and articles stating that a skater's optimal hollow has an inverse relationship with the skater's weight. In other words, when choosing a hollow, deeper hollows are often recommended for lighter players and shallower hollows are often recommended for heavier players. The rationale given for this guidance is that heavier players cut deeper into the ice and therefore will not require as much bite when turning and stopping.

Interestingly, I have never seen anyone bring up the fact that a heavier player creates significantly greater centrifugual force (F=MA) when turning which requires greater bite to overcome. This fact contradicts the premise above - that a heavier player requires a shallower hollow and a lighter player requires a deeper hollow.

Has the bite force, by weight, a hollow delivers ever been scientifically evaluated against the centrifugal force a skater generates?

I think the guiding principle is a myth without any scientific basis that has just snowballed through supporting what someone else said without questioning why. And, more importantly, providing this guidance is a diservice to new skaters who would benefit from a shallower hollow's greater glide while still retaining equivalent cornering speed through the use of edge control.

.

Just want to put in question a hollow guiding principle that affects us all.

Regards,

Holden Caulfield

I'll disagree.

F=ma doesn't really apply to "centrifugal force", which is a fictitious "force", but I understand what you mean. The heavier player may require what you call more "bite" to turn, but this is achieved by a combination of the weight and the edge, both contributing to friction, or centripetal force. Remember that the player weight is pushing that edge into the ice -- more weight, more push, more "bite", within a relevant range of angles. There's not necessarily a requirement for more edge.

As to being "scientifically evaluated", that's done by everyone who skates on a different edge, and notes how it affects the skating. No calculation can justifiably contradict an extensive body of empirical results. And I infer that just such a body exists, by the fact that you haven't found anyone contradicting the conventional wisdom.

Also, as Duncan points out, there are other phases of skating to consider, including glide and acceleration.

I think that less edge for heavier folks is a valid consideration, as part of a package, when determining which edge to try, but it's the testing that will determine what's best for an individual skater's style and desired results.

[Cavs019 702]

Were discussing this a bit here as well: http://www.modsquadhockey.com/forums/index.php?/topic/62890-716-radius-being-180lbs/

I think with sport, there is always an optimal vs comfortable, or more aptly, science vs. art. You may be able to determine the optimal curve, stick height, blade radius, ROH, from an efficiency or "physics" standpoint for a specific person, but that doesn't necessarily take into account the preferences/biases/"stubbornness" of the end user.

[Holden Caulfield 5]

JR:

Understand that most recommendations on hollow use weight as a factor rather than the rule, and agree that ice conditions, blade thickness, blade radius, blade height, skater's ability and personal preferences are all important factors in determining optimal hollow.

That said, what I am questioning is not that weight is a factor, but whether the guiding principle heavier/shallower, lighter/depper is valid. Most posts and articles I read not only state this guiding principle, but make it seem like it is one of the most important principles to follow when deciding skate hollow. This guiding principle fallicy ultimately leads to many skaters using sub-optimal hollows.

Bottom line - I believe that the guiding principle - heavier/shallower, lighter/deeper - should be stricken from the record as it is invalid and leads to suboptimal skate hollows. While it may be a factor, it cannot be turned into a guiding principle, and is only useful in making hollow recommendations in conjuction with the other factors you mentioned - there are many scenarios where weight will influence skate hollow recommendations opposite to the guiding principle.

Regards,

KB

[JR Boucicaut 3759]

Bottom line - I believe that the guiding principle - heavier/shallower, lighter/deeper - should be stricken from the record as it is invalid and leads to suboptimal skate hollows.

Curious - how much do you weigh and what do you skate on? And how did you come to that hollow?

I've known bigger guys on deep hollows - even professionals. They compensate for it by skating differently - they tend to "run" and use extremely choppy strides - hardly efficient. And of course, there's the inverse - I personally knew a NHLer who used to get his skates sharpened twice a season.

I still haven't seen anything here that is suggesting it's not a valid argument.

[Larry54 243]

Hi:

The internet is full of forum posts and articles stating that a skater's optimal hollow has an inverse relationship with the skater's weight. In other words, when choosing a hollow, deeper hollows are often recommended for lighter players and shallower hollows are often recommended for heavier players. The rationale given for this guidance is that heavier players cut deeper into the ice and therefore will not require as much bite when turning and stopping.

Interestingly, I have never seen anyone bring up the fact that a heavier player creates significantly greater centrifugual force (F=MA) when turning which requires greater bite to overcome. This fact contradicts the premise above - that a heavier player requires a shallower hollow and a lighter player requires a deeper hollow.

Has the bite force, by weight, a hollow delivers ever been scientifically evaluated against the centrifugal force a skater generates?

I think the guiding principle is a myth without any scientific basis that has just snowballed through supporting what someone else said without questioning why. And, more importantly, providing this guidance is a diservice to new skaters who would benefit from a shallower hollow's greater glide while still retaining equivalent cornering speed through the use of edge control.

.

Just want to put in question a hollow guiding principle that affects us all.

Regards,

Holden Caulfield

I think you make a very logical argument, just observing how the most popular hollows are between 1/2" and 5/8" regardless of body weight. I mean, I weigh barely over 140lbs and I've gotten along well in that hollow range and yet that's the same range of hollows that most 200lb NHL players use.

[JR Boucicaut 3759]

And 1/2" and 5/8" tend to be "house cuts" or the only options at local hockey shops.

I think you make a very logical argument, just observing how the most popular hollows are between 1/2" and 5/8" regardless of body weight.

I get it - I'd like to get every skater as shallow as they can go. But a lighter skater in a shallower hollow/heavier skater in a deeper hollow will feel the extreme end of the spectrum when it comes to bite and glide.

[donkers 31]

Hi:

The internet is full of forum posts and articles stating that a skater's optimal hollow has an inverse relationship with the skater's weight. In other words, when choosing a hollow, deeper hollows are often recommended for lighter players and shallower hollows are often recommended for heavier players. The rationale given for this guidance is that heavier players cut deeper into the ice and therefore will not require as much bite when turning and stopping.

Interestingly, I have never seen anyone bring up the fact that a heavier player creates significantly greater centrifugual force (F=MA) when turning which requires greater bite to overcome. This fact contradicts the premise above - that a heavier player requires a shallower hollow and a lighter player requires a deeper hollow.

Has the bite force, by weight, a hollow delivers ever been scientifically evaluated against the centrifugal force a skater generates?

I think the guiding principle is a myth without any scientific basis that has just snowballed through supporting what someone else said without questioning why. And, more importantly, providing this guidance is a diservice to new skaters who would benefit from a shallower hollow's greater glide while still retaining equivalent cornering speed through the use of edge control.

.

Just want to put in question a hollow guiding principle that affects us all.

Regards,

Holden Caulfield

I think the general rule of thumb that you stated are good starting off points but in the end it comes down to skater ability and preference.

[AfftonDad 88]

For what its worth (and I'm not saying it's worth anything), I just took the now famous Pittsburgh sharpening chart and cross referenced to player weights from NHL.com and then sorted from deepest to shallowest...

Deepest

Sidney Crosby 0.4375 200
Mike Rupp 0.4375 243
Chris Bourque 0.5 174
Tyler Kennedy 0.5 183
Chris Kunitz 0.5 193
Evgeni Malkin 0.5 195
Kris Letang 0.5 201
Deryk Engelland 0.5 202
Jay McKee 0.5 203
Matt Cooke 0.5 205
Brooks Orpik 0.5 219
Bill Guerin 0.5 220
Eric Godard 0.5 222
Alex Goligoski 0.625 181
Ryan Bayda 0.625 185
Max Talbot 0.625 190
Craig Adams 0.625 197
Ruslan Fedotenko 0.625 200
Pascal Dupuis 0.625 205
Nate Guenin 0.625 207
Mark Eaton 0.625 215
Jordan Staal 0.625 220
Martin Skoula 0.625 226
Chris Conner 0.75 180
Sergei Gonchar 1 206

Shallowest

[Holden Caulfield 5]

First, JR, I weigh about 155 lbs and skate on a 3/4" hollow. Started with standard half inch given my weight and never thought twice about trying something shallower. One day, I read an article about learning to use your edges rather than relying on your hollow and the extra glide you will get and haven't looked back. The germination of this thread started a while back when evaluating the logic behind the guiding principle and the curious ommision of the fact that weight (mass) impacts centrifugal force significantly (centrifugal - outward force the skate applies, centripetal - inward force the ice applies).

Ok, time to get super geeky. I ran a regression on the above data - the correlation is -.146 which implies very little correlation between weight and optimal hollow (assuming the NHL players have settled into their optimal hollows). Just one more data point supporting that the guiding principal of heavier/shallower hollow, lighter/deeper hollow is not valid.

I think that In the end, it is the other factors that are meaningful when trying to give guidance on an optimal hollow and that the guiding principal on weight should be dropped. Perhaps, the guiding principle should be high relative leg strength to weight/deeper hollow, low relative leg strength to weight/shallower hollow?

KB

[JR Boucicaut 3759]

Honestly, you're looking at this way too deeply. Do we send the skater to get a physical to determine how strong their legs are?

Yes, you WILL have to have strong legs to slog through on a deep hollow...because your legs will always be moving.

I am not trying to belittle you here, but do you sharpen? And have you sharpened for a living? If so, have you optimized a hollow for someone? This is not an attempt to discredit you, but optimizing a hollow for someone isn't easy - and it seems every response is pointed to me, someone who uses all of those factors listed. It takes quite a bit of time (and resistance from the skater in a lot of cases.)

[Neo5370 132]

Can't tell if OP is trying to be as pretentious as his handle....

[Wolfpack_1986 146]

Wrangler, centrifugal force is definitely applicable in this instance. It is a reactive centrifugal force (different from the ficticious centrifugal force) perceived by the non inertial reference frame of the ice. The cutting pushing the ice.

HC, in executing a turn, the force is not F=ma, the centripetal force would be Fc=mv^2/r.

So there's a number of different things here. the heavier skater exerts a larger force due to gravity. That's one thing. Another, in executing the turn, you could make the argument that the smaller player might be able to skate faster, perhaps enough to marginalize the force difference, or even exceed it.

But also deeper hollows have thinner edges near the bite surface, so the force from a heavier skater may make it easier to sheer.

Anyway, the moral of the story is, its a guideline and starting point. How much a player is a bender, weight, leg strength, and ice conditions all factor into what the correct hollow is. I don't think this guideline is so much based one scientific forethought as it is empirical evidence. More fat guys in the shop prefer this, skinny guys prefer that. If I have someone walk in and ask for their first sharpening ever, I'm going to based it empirically off skill level and weight.

[davidfinlay276 4]

Hi:

The internet is full of forum posts and articles stating that a skater's optimal hollow has an inverse relationship with the skater's weight. In other words, when choosing a hollow, deeper hollows are often recommended for lighter players and shallower hollows are often recommended for heavier players. The rationale given for this guidance is that heavier players cut deeper into the ice and therefore will not require as much bite when turning and stopping.

Interestingly, I have never seen anyone bring up the fact that a heavier player creates significantly greater centrifugual force (F=MA) when turning which requires greater bite to overcome. This fact contradicts the premise above - that a heavier player requires a shallower hollow and a lighter player requires a deeper hollow.

Has the bite force, by weight, a hollow delivers ever been scientifically evaluated against the centrifugal force a skater generates?

I think the guiding principle is a myth without any scientific basis that has just snowballed through supporting what someone else said without questioning why. And, more importantly, providing this guidance is a diservice to new skaters who would benefit from a shallower hollow's greater glide while still retaining equivalent cornering speed through the use of edge control.

.

Just want to put in question a hollow guiding principle that affects us all.

Regards,

Holden Caulfield

I don't think "centrifugal force" is really what you're looking for, but it's true that a heavier skater will have to apply more force to accelerate (change speed or direction). At the same time, he'll naturally sink deeper into the ice even with the same hollow, so with the same hollow he'll have more bite than a lighter skater would, and will thus be able to apply more force without losing his edge. These two factors probably more or less cancel each other out, but I don't really know.

The "heavier skater = shallower hollow" is just meant to be a starting point, not a hard and fast rule. It is true that a heavier skater will need a shallower hollow to get the same glide as a lighter skater. The bite a skater needs to hold their edge, on the other hand, is WAY more complex, and is quite frankly determined far more by a skater's technique and preferences than their weight. Great skaters can generally hold an edge through tight turns even with a really shallow hollow, because their balance is just excellent, while weaker skaters might have to rely on a deeper hollow. Also, some people just like the feel of a deep bite, and will feel hesitant to really lean into turns even if their technique would allow them to hold an edge just fine. Skating/playing style can also come into play - if you're a skater with a long stride who really flows and glides, a shallow hollow probably works better for you, but if you take shorter/choppier strides and tend to stop and start a lot, you probably want to be able to really dig in with those edges. Guys who engage in a tonne of physical/strength battles will also probably like a deeper hollow, to really dig in and push.

The simple truth is that the vast majority of skaters are pretty happy with a 1/2" hollow. If they feel they need more bite, they can try something deeper. If they feel they have enough bite, they can stay with their current hollow if they aren't picky/adventurous, or can try a shallower hollow, which they can stay with if they like the improved glide and don't really notice the loss of bite.

[Wolfpack_1986 146]

I am so proud that everyone knows about centripetal force, and that centrifugal is ficticious and the like... But the force is across intertial reference frames and is valid. He's not wrong.

[oldtrainerguy28 478]

Just for the record yes there has been studies done on hollow and player weight and so on here at one of the Universities. If you google Brock University and skate sharpening you should find the study information there. If you cannot let me know and I will see if I can get it.

I personally use 5/8th's as my starting point and usually go down to less sharp from there. Not to often do I go sharper. Only a couple players but mainly goalies at the top end of the player caliber.

[flip12 699]

And of course, there's the inverse - I personally knew a NHLer who used to get his skates sharpened twice a season.

I believe that, but it still blows my mind.

[salibandy 21]

Definitely don't think lighter/deeper, heavier/shallower is a hard and fast rule. I'm 110lbs, and am very comfortable on a 1/2 inch hollow. However, my local sharpener insists on putting a 3/8ths because I am light. I tell him, I can't stop on a 3/8ths (can't even snowplough if standing still), but I can cut hard and stop fine on 1/2, if you put me on a 3/8ths, it'll be dangerous for me. The ice here is really soft, so I tell him that's why I want a 1/2. He tells me my skating sucks if I can't skate on a 3/8ths at my weight. I think that's ridiculous.

[Monty22 821]

Definitely don't think lighter/deeper, heavier/shallower is a hard and fast rule. I'm 110lbs, and am very comfortable on a 1/2 inch hollow. However, my local sharpener insists on putting a 3/8ths because I am light. I tell him, I can't stop on a 3/8ths (can't even snowplough if standing still), but I can cut hard and stop fine on 1/2, if you put me on a 3/8ths, it'll be dangerous for me. The ice here is really soft, so I tell him that's why I want a 1/2. He tells me my skating sucks if I can't skate on a 3/8ths at my weight. I think that's ridiculous.

Sounds like you need to find a new sharpener.

[fcvapor05 1]

By this logic, if everyone was targeting the same 'bite' in a turn, everyone would use the same hollow radius, since weight and force into the ice are directly proportional. A lighter player doesn't need more 'bite' than a heavier one, because it takes less force to move a lighter player's body.

Hollow radius is no more complicated than personal preference.

[salibandy 21]

Sounds like you need to find a new sharpener.

I was actually thinking of getting an X01 from Blackstone, but I would have them to put in a different motor for the current here or buy a transformer. But money's a little tight now, so I am stuck. He's the most competent sharpener in the country, but very stubborn. I tried to correct him once about coincidental penalties and got yelled at (I was doing scorekeeping). I had to beg him before he agreed to sharpen my skates to 1/2; prior to this, I had been surviving on a lady who does FBV, but she frequently gets her edges uneven, and after correcting her one too many times about her uneven edges, I've been booted from the shop. Probably shouldn't have taken her edge checker and shown her what kind of edges she was getting.