I started a discussion on another board about how (new) blade shapes vary with length. So far one person has offered to measure their old (used) blades, but no one has responded who actually knows.

Does anyone here know?

Is there any variation of rocker radius, length of rocker sections, or positions, as length changes, within a given brand and model?

If there isn't, then, for example, on many blades, the point where you are on the rockered section, when the toepick starts to touch (which some coaches teach is where you do turns, and where many coaches teach you should do a scratch spin) would be in the middle of a very short foot, but maybe in the toes of a very long foot. (That's assuming a specific convention for full custom boots in which the front of blade mounting plate is at the front of the outsole, which is in turn the length of a radial projection of the skater's foot. I.E., the front of the mounting plate radially projects to the front of your toes too.) Yet many coaches tell their students to use the same model blades they use, even if their feet aren't the same size.

So, is there some type of scaling, and if so, exactly what?

I haven't been able to find a source on this.

It would be wonderful if someone here with full access to a pro shop could scan (at as high a resolution as possible) a short and long new unsharpened blade of the same model, and place the images somewhere (right now skatingforums doesn't seem able to attach images any more - I couldn't even attach the small one I linked to in my recent thread on 7 & 8' rockers). 

A lot of people claim it is harder to center spins, but easier to land jumps (for stability), on 8 foot rockers. Including some on this board.

I don't know how well controlled any experiments they ran are.

I.E., other blade shape factors differ too, blade to blade. As perhaps they should? All other things being equal, an 8' rocker would otherwise lift the toepick less off the ice.

I think you are implying there are psychological factors too.

My point though was that a skate tech would probably have to take a measurement to see the difference. Given the minimal training a lot of them have, and the pressure to sharpen as many blades/hour as they can, I wouldn't expect most of them to notice the difference.

The more pertinent question is:  "Can a skater feel the difference between an 8' vs a 7' radius main rocker?"  Similar to previous discussions on:  "Can a skater feel the difference between a 3/8" vs a 7/16" vs a 1/2" radius of hollow?"  This is the criterion that I refer to as "the proof of the pudding".

It is pretty nuts to see the slight difference. 

I've tried two blades with 7', but briefly, and they felt nice but not so different than the two 8' I have spent a lot of time on.  I'm firmly in the camp of believing skaters can easily adapt to different blades if they want to, and a skilled skater can do great things on pretty much any blades.  *Bleep* rentals though.   

http://mgrunes.com/boots/DrawArcs/Compare7_8foot.png
is a 1200 pixel/inch drawing of 7 & 8 foot rocker curves. If viewed with Firefox or Chrome, you can see the lines, which are only 1 pixel wide. Not sure about other browsers.

The curves are so close!

The scales have 16 tics/inch, 1 big tic/inch.

Yet we mean skaters dare claim 8' rocker blades are faster and more stable, and 7' blades turn and spin better.

Pity the poor maligned skate techs who only think they are doing a good job. Virtually invisible changes can make customers upset.

(P.S. It was an easy mod of a program I created to draw many scaled rockers at http://mgrunes.com/boots/DrawArcs, used to measure blade shapes.)

Sigh, my otherwise favorite rink has had troubles this season.

https://www.cityofbowie.org/105/Ice-Arena
https://www.facebook.com/bowieicearena

I don't yet measure the relative height and forward position of the mounting plate, but that's very Important. AFAICT, on a full custom boot, the front and back of the outsole radially projects to the front and back of the foot. Skate techs try to place the front and if possible the back of blade mounting plate to match the outsole (makes little sense on non-custom boots!). So the "blade length", which is  measured from the mounting plates, is the radially projected foot length of the foot, or slightly shorter, on full custom boots. (True for all custom brands??)

Even within freestyle blades, the radially projected back toepick tooth projects to a part of the foot (or ahead of it) that depends on blade model. Interesting. (And which radial line direction should you use to measure that?)

Perhaps an expert sharpening should always trim the back back toe tooth in a way that continues to radially project to the center of the ball??

I've been told (is it true??) that the front parts of blades - all rocker radii, length of all but the main rocker segment - is the same for all blade lengths of given MK or JW model. It would means the lift height depends a lot on the blade length, and as feet grow, a given model would interact very differently with them in many ways.

E.g., "lift height" of the blade - the height of the blade back ("tail") when on the modified sweet spot, would change a lot with length. Is that true?

Oh. The guidelines for one of the skate forums I use say the rules for links to external sites must be

QuoteLinks to established news sites
Links to Youtube, Instagram, X, and Facebook
Links to non-commercial personal sites, blogs, channels, etc. are only permitted in the Share It forum as long as there is a reciprocal link.

My personal website isn't commercial:, but that might change, and it links to commercial sites. My Facebook page still has stuff from when I ran a math tutoring business. And Before sites verified email, evil people opened accounts at the other major social media sites, giving my email address.

If I post Postscript for my generated images, many people don't have GhostView or equivalent to read it. And you need the assumed paper size so GhostView displays and prints it right. Plus my current programs print long versions of numbers for accuracy and alignment, using Fortran g0 and i0 formats, so my postscript files are long. I could shorten them for posting... But Skatingforums lets me add the actual images, though that's a bit dangerous - some image formats can embed malicious code.

Am I using the wrong reference points? My "sweet spots" are where rocker curvature changes. I've been placing the sweet spot (the back one if there are 2) horizontal on my output horizontal, because some say that is where you  turn and spin. I find it by seeing where the blade or its tracing departs my rocker curves, but its hard to be accurate.

It's much easier to measure what I call the "modified sweet spot" - the point on the blade where the toe pick starts to touch on a rigid surface. Some say that is where you turn and (scratch) spin. (But AFAICT, when 3 rocker segment JW blades are new, the modified sweet spot IS the forward sweet spot.)

Some expert skate techs modify blades so one or the other of these sweet spots is radially projected to the center of the ball of the foot, which in turn, should be the place where the upward bend of the footbed is centered, for foot health and to prevent sliding.

But every sharpening, the modified sweet spot moves back a fair bit, unless you trim the back toepick tooth enough to keep it stable. Should expert sharpeners do that?

I still need my version of "sweet spots" (and rocker radii) to define and draw the shape of the blade. But if I switch to "modified sweet spots", inaccuracy won't matter as much.

Yep, lot's of consolidation in this niche business.  Step mainly manufactures runners for hockey skates.  They also had their own line of figure skate blades, as well as being contract manufacturers for Skate Science and Eclipse.  Step is now owned by CCM.  And Jackson Ultima is now owned by Sport Maska, the parent company of CCM. 

Step no longer lists their own line of figure skate blades; Skate Science went poof; and since Jackson Ultima is a direct competitor of Riedell Eclipse, Step no longer manufactures Eclipse blades. It would be logical for Step to manufacture Ultima blades, but who knows? Corporate mergers often do not lead to logical processes.

We had another thread discussing step skates
  https://skatingforums.com/index.php?topic=7802.0

But that website
  http://stepskates.com
now redirects to
  https://ca.ccmhockey.com/en/Skates/Step-Steel-Blades
which I guess is the Canadian CCM distribution or manufacturing site (?). The only blades they now sell are hockey blades.

This company says they still have Step Steel figure blades in stock:
https://jumpsudbury.ca/search?q=Step%20Figure%20Skate%20Blades

And here is a lot of 6 pairs of Step Steel figure blades for $250.
https://sidelineswap.com/gear/figure-skating/figure-skates/8516998-figure-blades-lot-f-6-pairs-of-skate-science-by-step-blades-synchro-double-triple-dance?srsltid=AfmBOor_dYPmaNtBPVZomKUtDFAvDrUcT3MDfpjjMSGMaK1yW5aiwTS6

Quote6 pairs of blades by Skate science/ Step

1 x 10.5 double triple
2 x 10 double triple
1 x 9 dance
1 x 10.25 synchro
1 x 10.5 synchro

Those are likely closeout or surplus prices, so may no longer be made.

And then there is Blade Science
https://www.blade.science
https://www.facebook.com/BladeScience

At first I thought they were the same company as SkateScience. But no. They design blades that cushion landings.