Page 1 of 2 12 LastLast
Results 1 to 20 of 25

Thread: How different radius of hollow affect skating?

  1. #1
    Rinkside
    Join Date
    May 2018
    Posts
    54
    Country: Italy

    1 Not allowed!

    How different radius of hollow affect skating?

    Hi everyone,
    I'm interested in learning more about techinal aspects of figure skating blades and how this can improve or hinder one's skating abilities. I've read something about different radii on skaters landing website, but it wasn't so illuminating as I expected. I skate in Mk Pros , 7/16'' ROH. Previously, I had Edea Charme , that has three different segment radii. I really felt the difference between the two blades. Mk Pros feel smoother and faster, shaper during turns but somewhat less "stable" .On the contrary, Edea Charme felt more stable (not in jumps)but difficult to handle sometimes.The rocker is also different and it seems to be the most debated topic when comparing blades, but I think there might be more than that. So I started looking for information about ROH. My question is: if I skated in 7/16",5/8", 3/4", or 1/2" ROH, would I notice any difference? Would some elements be performed better or worse?
    Thanks in advance to all of you willing to answer this crazy question 😅
    Last edited by thesoundofice; 08-01-2019 at 08:50 AM. Reason: Mistake

  2. #2
    On the Ice
    Join Date
    May 2018
    Posts
    282
    Country: United States of America

    2 Not allowed!
    So, the standard or I guess starting point for most skaters is 7/16". ROH can be adjusted by the sharpener. The vast majority of all blades leave the factory at this ROH.

    I currently skate at a 10mm ROH which is close to 6.3/16". This means my blade feels sharper because the radius goes deeper. The downside of this is that the edge can be more susceptible to dings and knicks because it's thinner and more fragile.

    The deeper or the smaller the number of your ROH the more grippy of an edge you'll have. This means that you might feel slower. I've noticed that my edge jumps (my favorite) take off much easier the deeper my ROH. I also feel like I have more control in turns and footwork. Spins are supposed to be slower, but for me, because the edge into the spin is better, my spins are overall better.

    I definitely wouldn't use a radius larger than 7/16 when you ask for a sharpen. Your edge will dull a bit, and a lot of skaters like their edge best 1-2 weeks after a sharpen. I like very grippy blades so the first 2 weeks after my sharpen are the best for me.

  3. #3
    Alyona Kostornaya - skating off into the unknown.. Edwin's Avatar
    Join Date
    Jan 2019
    Posts
    1,872
    Country: Netherlands

    1 Not allowed!
    Thanks for the postings.

    A question for clarification:
    ROH is crosswise radius of the hollow of the blade, as opposed to rocker, the lenghtwise radius of the blade?

  4. #4
    On the Ice
    Join Date
    Feb 2018
    Posts
    281
    Country: United States of America

    1 Not allowed!
    Quote Originally Posted by Edwin View Post
    Thanks for the postings.

    A question for clarification:
    ROH is crosswise radius of the hollow of the blade, as opposed to rocker, the longitudinal radius of the blade?
    You got that right; ROH stands for "radius of hollow".

  5. #5
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    4 Not allowed!
    Quote Originally Posted by thesoundofice View Post
    So I started looking for information about ROH. My question is: if I skated in 7/16",5/8", 3/4", or 1/2" ROH, would I notice any difference? Would some elements be performed better or worse?
    Thanks in advance to all of you willing to answer this crazy question 
    This is not a crazy question at all. ROH is a key parameter that affects your skating. And unlike the rocker profile (which very few skate techs have the capability to change), ROH can be readily changed by skate techs (on standard power sharpeners, the wheel can be dressed to a particular ROH).

    For beginner and freestyle blades, common values of ROH are 7/16" and 1/2". The extreme range runs from 5/16" to about 3/4". In general, the smaller the ROH, the sharper the edges; and, in general, a sharper edge gives more bite into the ice and also has more drag. So, in general, a small ROH (such as 3/8") will make it easier for maneuvers that require deep edges (such as cross-overs and quick turns) at the expense of reduced glide on straighter strokes.

    I say "in general", because as always there are exceptions. Some advanced skaters (such as the top skater at my rink) use a large ROH (such as 3/4") for high speed overall and get deep edges through good technique; this requires a high level of skill.

    Proper choice of ROH is highly a matter of individual preference. Some factors include:

    * The skater's weight (a heavier skater will cause edges to bite in deeper; so a larger ROH may be favorable for heavier skaters, and a smaller ROH may be favorable for lighter skaters);

    * Ice temperature (of course, a skater has no control over this; higher ice temperature leads to softer ice, and edges will bite in deeper in softer ice; so a larger ROH may be favorable for higher ice temperatures, and a smaller ROH may be favorable for lower ice temperatures; at some rinks, the ice is consistently softer during the summer months than during the winter months, so some skaters have a summer ROH and a winter ROH; but at my rink, the ice varies daily, so I stick to one ROH year round);

    * Blade thickness (for a constant ROH, the edge angles vary as a function of thickness; for a fixed value of ROH, the edges on a thicker blade will be sharper than the edges on a thinner blade; the thickness of freestyle blades do vary; this is of more particular consequence for slimline/thinline dance blades (to get the same sharpness on a thinner dance blade as on a thicker freestyle blade, the ROH for the dance blade needs to be smaller than the ROH for the freestyle blade);

    * Your skating skills (one strategy is to use the largest ROH that still affords you proper control).

    If you're a beginner, play around with 7/16" and 1/2". As you become more advanced, you can experiment with other values. Be aware though that overly frequent changes in ROH will shorten the service life of your blades (if possible, start large and go progressively smaller; avoid flip-flopping between larger and smaller).

  6. #6
    Rinkside
    Join Date
    May 2018
    Posts
    54
    Country: Italy

    0 Not allowed!
    Thanks for your answers. Nimyue and Tstop: you couldn't have been more illuminating. I really needed a clear and accurate explanation. Considering skating skills I'm halfway between beginner and intermediate ( all singles, all basic spins). I feel comfortable skating with 7/16". In the past I tried 1/2" (ultima Mirage) but didn't like it at all. Edea Charme ( three different radii, couldn't find specific values) was ok . Mk Pros are perfect. I think I'll stick to 7/16" at least until I improve my skills.

  7. #7
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    0 Not allowed!
    Quote Originally Posted by thesoundofice View Post
    Thanks for your answers. Nimyue and Tstop: you couldn't have been more illuminating. I really needed a clear and accurate explanation. Considering skating skills I'm halfway between beginner and intermediate ( all singles, all basic spins). I feel comfortable skating with 7/16". In the past I tried 1/2" (ultima Mirage) but didn't like it at all. Edea Charme ( three different radii, couldn't find specific values) was ok . Mk Pros are perfect. I think I'll stick to 7/16" at least until I improve my skills.
    I sent you a PM. The notification system doesn't always work, so please check your inbox.

  8. #8
    Alyona Kostornaya - skating off into the unknown.. Edwin's Avatar
    Join Date
    Jan 2019
    Posts
    1,872
    Country: Netherlands

    1 Not allowed!
    Is it common for pro skaters like those participating in ISU GP and such to have different sets of blades for different ice conditions they meet?

  9. #9
    Forever respecting the sport
    Join Date
    Jan 2017
    Posts
    5,226

    2 Not allowed!
    Quote Originally Posted by Edwin View Post
    Is it common for pro skaters like those participating in ISU GP and such to have different sets of blades for different ice conditions they meet?
    First of all, they aren't pros if they are skating in GP's and other sanctioned competitions like that etc.. They are elite.
    And from personal experience, no we do not.

  10. #10
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    1 Not allowed!
    Quote Originally Posted by thesoundofice View Post
    Thanks for your answers. Nimyue and Tstop: you couldn't have been more illuminating. I really needed a clear and accurate explanation. Considering skating skills I'm halfway between beginner and intermediate ( all singles, all basic spins). I feel comfortable skating with 7/16". In the past I tried 1/2" (ultima Mirage) but didn't like it at all. Edea Charme ( three different radii, couldn't find specific values) was ok . Mk Pros are perfect. I think I'll stick to 7/16" at least until I improve my skills.
    <<Emphasis added.>> By the way, the three different radii for the Charme refers to the rocker profile, NOT three values of ROH. If they were to introduce such a blade, most skate techs would probably refuse to sharpen them; or charge so much it wouldn't be viable.

  11. #11
    Alyona Kostornaya - skating off into the unknown.. Edwin's Avatar
    Join Date
    Jan 2019
    Posts
    1,872
    Country: Netherlands

    0 Not allowed!
    Quote Originally Posted by tstop4me View Post
    <<Emphasis added.>> By the way, the three different radii for the Charme refers to the rocker profile, NOT three values of ROH. If they were to introduce such a blade, most skate techs would probably refuse to sharpen them; or charge so much it wouldn't be viable.
    A computer controlled laser aided 6 axis DOF milling/sanding/burring machine would probably do the trick in the blade factory, working on the raw metal, but is prohibitively expensive for a shop fitter. He has to rely on his tools, eyes and skill.

  12. #12
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    2 Not allowed!
    Quote Originally Posted by Edwin View Post
    A computer controlled laser aided 6 axis DOF milling/sanding/burring machine would probably do the trick in the blade factory, working on the raw metal, but is prohibitively expensive for a shop fitter. He has to rely on his tools, eyes and skill.
    On most commercial power sharpeners, the ROH is changed by dressing the abrasive wheel. There are a few power sharpeners in which the wheel comprises a mandrel with a fixed ROH coated with an abrasive. If a blade were to have three separate ROHs (along different longitudinal sections of the blade), he would need to sharpen the three different segments individually, redressing the wheel for each segment, or changing mandrels for each segment. Very time consuming, and difficult to manage the transitions.

    If you want to vary the blade angles along the length of the blade, you can more readily do that by maintaining a constant ROH and varying the thickness of the blade. That's what some blade manufacturers do (e.g., tapered or parabolic blades). ETA: If you make a blade that needs to be returned to the factory for sharpening, you probably won't sell too many.

  13. #13
    Rinkside
    Join Date
    May 2018
    Posts
    54
    Country: Italy

    0 Not allowed!
    Thanks for the clarification. I'm not an expert but I'm curious and I'd like to learn more about blades. Honestly I wondered how those blade could be sharpened if they had different ROH. I thought It would be a nightmare but didn't understand that I was wrong 😅

  14. #14
    Alyona Kostornaya - skating off into the unknown.. Edwin's Avatar
    Join Date
    Jan 2019
    Posts
    1,872
    Country: Netherlands

    0 Not allowed!
    Quote Originally Posted by tstop4me View Post
    On most commercial power sharpeners, the ROH is changed by dressing the abrasive wheel. There are a few power sharpeners in which the wheel comprises a mandrel with a fixed ROH coated with an abrasive. If a blade were to have three separate ROHs (along different longitudinal sections of the blade), he would need to sharpen the three different segments individually, redressing the wheel for each segment, or changing mandrels for each segment. Very time consuming, and difficult to manage the transitions.

    If you want to vary the blade angles along the length of the blade, you can more readily do that by maintaining a constant ROH and varying the thickness of the blade. That's what some blade manufacturers do (e.g., tapered or parabolic blades). ETA: If you make a blade that needs to be returned to the factory for sharpening, you probably won't sell too many.
    Tapering a blade seems the reasonable solution, as the effect (effective contact surface when skating on the edges, right?) will be the same.

  15. #15
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    3 Not allowed!
    Quote Originally Posted by Edwin View Post
    Tapering a blade seems the reasonable solution, as the effect (effective contact surface when skating on the edges, right?) will be the same.
    Not sure what you mean by effective contact surface in this instance. But I view the scenario in terms on the included edge angles. Think of the inside skate edge and the outside skate edge in terms of the edge of a knife. Each skate edge is defined by the intersection of two surfaces: one surface is the curved hollow, the other surface is the flat exterior surface of the skate blade (outside or inside exterior surface). The included angle at the intersection defines how sharp the skate edge is. Just as in a knife blade, the smaller the included angle, the sharper the skate edge. For a fixed value of the ROH, the included angle varies with the thickness of the skate blade: the thicker the blade, the smaller the included angle and the sharper the skate edge.

    In a tapered skate blade, the thickness is greatest near the picks, and decreases progressively towards the heel; therefore, the skate edges are sharpest near the front of the blade, and gets progressively less sharp towards the rear of the blade. This provides extra bite for maneuvers (such as turns and entrances to spins) that use the front of the blade; and extra glide for maneuvers that use the middle and rear of the blade.

    For a parabolic blade, the blade is thicker near the pick and heel, and thinner near the middle. This provides a more longitudinally symmetric blade: more bite towards the front and heel; and extra glide near the middle.

    I've sent you a PM to one of my posts in another forum. It has a diagram and all the relevant math.

  16. #16
    Rinkside
    Join Date
    May 2018
    Posts
    54
    Country: Italy

    0 Not allowed!
    Would someone be so kind to explain the difference between tapered and parabolic? Thanks

  17. #17
    Tripping on the Podium
    Join Date
    Oct 2015
    Posts
    599
    Country: United States of America

    2 Not allowed!
    Quote Originally Posted by thesoundofice View Post
    Would someone be so kind to explain the difference between tapered and parabolic? Thanks
    I'll try to explain as best as I can using keyboard characters, in lieu of a drawing. Suppose you're holding one skate in front of you, edges facing you, vertically oriented with picks on the top, heel on the bottom. Imagine the edges projected onto a plane, such as a flat screen (as if you were viewing them on a camera LCD screen).

    * With parallel edges, the outside and inside edges are configured as such: ||. The edges are straight lines, and the lines are parallel. The thickness of the blade (transverse distance measured between the outside and inside edges) is nominally constant along the length of the blade.

    * With tapered edges, the outside and inside edges are configured as such: \ / (greatly exaggerated). The edges are straight lines, but the lines are not parallel, The thickness of the blade progressively decreases from near the picks (thickest) to the heel (thinnest).

    * With parabolic edges, the outside and inside edges are configured as such: ) ( (greatly exaggerated). The edges are concave curves. The blades are thicker near the picks and the heel and thinner near the middle.

  18. #18
    Rinkside
    Join Date
    May 2018
    Posts
    54
    Country: Italy

    0 Not allowed!
    So.. tapered and parabolic blades are quite similar because they both vary in thickness. Anyway they are different both in shape and in thickness distribution along the blade surface. Thanks so much for your explanation.

  19. #19
    On the Ice
    Join Date
    Feb 2019
    Posts
    117

    0 Not allowed!
    Quote Originally Posted by tstop4me View Post
    I'll try to explain as best as I can using keyboard characters, in lieu of a drawing. Suppose you're holding one skate in front of you, edges facing you, vertically oriented with picks on the top, heel on the bottom. Imagine the edges projected onto a plane, such as a flat screen (as if you were viewing them on a camera LCD screen).

    * With parallel edges, the outside and inside edges are configured as such: ||. The edges are straight lines, and the lines are parallel. The thickness of the blade (transverse distance measured between the outside and inside edges) is nominally constant along the length of the blade.

    * With tapered edges, the outside and inside edges are configured as such: \ / (greatly exaggerated). The edges are straight lines, but the lines are not parallel, The thickness of the blade progressively decreases from near the picks (thickest) to the heel (thinnest).

    * With parabolic edges, the outside and inside edges are configured as such: ) ( (greatly exaggerated). The edges are concave curves. The blades are thicker near the picks and the heel and thinner near the middle.

    This is really interesting. I guess that having a thicker blade near the pick helps the spin and turns, but I wonder what is the advantage or disadvantage to have a thinner (tapered edge) or thicker blade (parabolic edges) near the heel.

    Btw it is amazing you can explain all this information without a graph. Great job!!

  20. #20
    Alyona Kostornaya - skating off into the unknown.. Edwin's Avatar
    Join Date
    Jan 2019
    Posts
    1,872
    Country: Netherlands

    0 Not allowed!
    Yes, skating in itself is an interesting sport on the physics part.

    Speed skaters use long straight blades, hinged at the toes to propel the stroke better, in the 400 mtr sprint, speeds of up to 70 Km/h are achieved!
    Short track skaters use very thin curved blades, fixed but with high pedestals so they can really lean into those tight curves.
    Hockey skaters use short thick blades, I assume to them both the rocker and radius of hollow are very important due to the manoeuvrability needed while battling it out in a match
    Figure skaters also use short thick blades, but theirs can be thinner than hockey skaters since there is less wear and tear because no fighting on the ice, and the diverse disciplines have different requirements re curves and edges.

    How does the actual area of contact surface differs between those branches of skating? There must a minimum contact surface area, otherwise you'd sink into the ice?
    Hydroplaning is the key of skating, but has this actually been studied in great detail, i.e. is there a 'bow wave' to climb? I guess it is all very minute and any advantage/disadvantages are only marginal. But inquiring minds want to know ...

    Track cycling materials, technique and mechanics have been studied very closely and affluent programs that have the means have bettered their results considerably though applied science.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •