Both live on the same 3mm of steel, both are changed by a person with a grinding wheel, and both alter how your skate “feels.” But they answer different questions. Hollow: how hard do my edges grip when I lean? Profile: where is my weight, and how much blade is under it?

The confusion has a cost. A skater whose profile has drifted feels “off,” asks for a different hollow, feels different-but-still-wrong, changes hollow again — and ends up three changes deep with no idea what did what. Meanwhile the actual problem was the platform.

The Dude Rule: never change profile and sharpening at the same time while testing. Bauer’s own profiling guidance says the same thing — isolate one variable so you know what actually helped. Lock your hollow, change the profile, test it clean. One lever at a time is the entire discipline.

The formula. When a curved blade presses a small depth d into the ice, the loaded contact length is approximately L = 2√(2Rd). The exact length depends on your weight and the ice (that’s d), but the ratios between radii don’t — contact scales with √R for the same skater on the same ice. Indexed against a stock 9' profile:

• 7' radius≈ 88% of stock contact — quickest pivots, least support
• 9' radius100% — the stock-steel reference point
• 10–11' radius≈ 105–111% — noticeably calmer glide
• 13' radius≈ 120% — long-contact stability (and the youth-skate trap in lecture 8)
• 28–30' (goalie)≈ 175–183% — a different discipline entirely (lecture 10)

Why a few millimeters matter so much. Your contact patch is on the order of an inch or two long. A profile change moves that by a few millimeters — a 10–20% change to the entire platform your balance system is standing on. Tiny absolute numbers, enormous proprioceptive difference. This is also why “I can’t describe it, it just feels different” is a completely legitimate profiling review.

One more variable players forget: steel height. As your runner wears down from sharpenings, you lose leverage and the same profile sits differently. A profile evaluation always starts with how much steel you have left — sometimes the honest answer is “new steel first.”

Flatter (bigger radius): more contact → more speed, more stability, calmer balance at pace, more efficient long strides. The cost: slower to initiate turns, heavier-feeling pivots, lazier first steps.

Rounder (smaller radius): shorter contact → quicker pivots, snappier acceleration, easier tight turns. The cost: less support at speed, twitchier balance, more work to stay calm in straight lines.

Weight matters here too. A heavier player loads the patch deeper (more effective contact) and can afford a rounder profile without feeling twitchy; a light player on the same shape may feel like they’re balancing on a marble. Same logic as hollows in Sharpening 101 — pressure changes everything.

And this is why combination profiles exist. A single radius gives all four zones the same curve — one compromise stretched across four jobs. Multi-radius profiles (lecture 6) give the toe a quick curve and the heel a stable one, so you stop choosing. That’s the entire premise of modern profiling.

Pitch is measured in fractions of a degree. Professional profiling systems offer graded steps — roughly 0.5° (slight), 1° (moderate), and 1.5° (aggressive) of forward lean. On paper that’s nothing. Underfoot, half a degree changes your resting posture, your knee bend, and which muscles hold you up all game. If your calves are wrecked after every skate, suspect pitch before fitness.

Your holder already has an opinion. Different holder brands carry different built-in stance geometry — switching skate brands can change your effective pitch with zero profiling. It’s why “my new skates feel weird” is sometimes a pitch story, not a boot story, and why a profile should be evaluated on your holders, not in the abstract.

Who tends to want what: forward-pitch bias suits attacking forwards who live on their toes and players trying to unlock knee bend. Neutral suits defensemen who skate backward for a living, players with balance complaints, and anyone testing a new profile — always test new profiles at neutral first, so you learn what the shape itself is doing before you stack a stance change on top of it.

Stay single-radius when: you’re a developing skater who needs predictability while fundamentals form; you want one variable you can reason about; you’re testing your way toward a combination profile and need a clean baseline; or your game genuinely lives at one end of the tradeoff (pure grinder, pure straight-line skater).

Move on when: you can name two things you want at once — “quicker first steps AND calm at speed” is the literal definition of a combination profile, and no single circle can give you both. A flatter single (11'–13') can also demand a shallower hollow to keep turn-in manageable — more contact means more total grip, and the two systems interact. That interaction is exactly why The Dude tunes them as a pair, one variable at a time.

Professional profiling runs on documented templates, not freehand. The families you’ll hear about — with real radii:

• Duals7'–13' (strong glide, forward-pitch feel) · 8'–12' (same idea, calmer) · 9.5'–10.5' (barely off stock — light, balanced; the McDavid neighborhood). Sharpest hand-off between curves; some skaters feel the transition.
• Triplese.g. 6'–12'–16' (the Zuperior family) · junior 5'–10'–13'. Agile toe, flat stable heel, slight forward feel — a popular “best of both” step past duals.
• Quadse.g. 6'–9'–11'–13' (Quad Zero family) · 7'–10'–13'–16' (Quad 2 — maximum platform) · junior 5'–8'–10'–12' · smallest sizes down to 4'–5'–7'–10'. The smoothest transitions of all — four jobs, four curves, no compromise.
• Size scalingTemplates come graded by holder size — roughly junior (≤246), standard (254–272), large (272+). A profile is proportional to the blade: a kid doesn’t get a shrunken adult shape, they get radii scaled to their steel. This is half of why youth profiling is its own conversation.

How to read all those numbers: don’t. Read the pattern: small number at the toe, big number at the heel, smooth hand-offs in between, scaled to your blade length. The right question isn’t “which template?” — it’s “what do I want more of, and what am I willing to trade?” Then the template picks itself.

How center-flat numbers work. A spec like “30/60” means a 60mm total flat with 30mm of it ahead of blade center. Flats run roughly 40–80mm, and shifting more of the flat forward of center builds in forward-pitch bias (a 50/50 split is neutral; ≈60/40 is a light forward bias; ≈67/33 is aggressive). Two numbers encode both the platform size and the stance.

Public NHL center-flat setups — real players, real numbers:

• Sidney Crosby30/60 — 60mm flat, moderate forward bias
• Nathan MacKinnon35/65 — big platform for a power engine
• Cale Makar15/30 — tiny flat; nearly all rocker, maximum elusiveness
• Evgeni Malkin40/80 — the maximum-platform end
• Quinn Hughes35/55 — mid-size flat, forward-shifted

Read that table carefully and you’ll notice the lesson: Makar and Malkin are both elite — on opposite ends of the same system. Same as the goalies in Sharpening 101: at the top, setup is personality. The system gives you the levers; your skating decides the numbers.

Cautions: a long flat on a short blade creates a “railroad track” feel — hard to initiate turns — which is why small skaters start with small flats. And ellipse profiles shift the pivot point slightly rearward by design — part of why they feel calm — so they’re a deliberate choice, not a novelty upgrade.

Why it ships this way: a brand-new skater’s biggest enemy is falling, and the 13' platform is genuinely the right call for week one — stability sells skates and keeps kids on the ice. The problem is nobody tells parents it’s in there, so kids who can already skate spend seasons on a profile designed for someone who can’t. The fix isn’t exotic: a scaled profile matched to weight and stage (the junior templates in lecture 6 exist precisely for this).

Factory problem #2 — inconsistency. Stock steel is mass-ground. Left and right runners can leave the factory with slightly different shapes, and replacement steel won’t match what your last profile became after a season of sharpenings. If one skate turns better than the other, that’s a matching problem, not a you problem.

Factory problem #3 — “new steel, weird feel.” Buy replacement runners and you’re back on the factory 9'/10' — your profile didn’t transfer. New steel should be profiled to your spec before it ever sees the ice. That’s why The Dude records your profile in your customer file: your shape follows your steel, not the other way around.

Walk in and say four things: “Here’s what I’m feeling. Here’s what I want more of. Here’s my current cut. I want to change one variable and test it properly.” That sentence makes you the easiest customer of the week and gets you a better result than any amount of profile vocabulary.

What a legit profiling job includes — hold any shop to this: runner prep and truing before shaping; left/right matching (height and contour); controlled, repeatable removal; and verification plus documentation, so your profile can be reproduced on your next steel. If a shop can’t tell you what they did, they can’t do it again.

• Single-radius goalieMid-20s to ~30' (25/27/29/30 are common menu numbers; ~30' ≈ stock). Predictable stance, consistent shuffles — the baseline.
• Goalie duale.g. 26'–30' — slightly quicker front over a stable rear: keeps the planted stance but speeds lateral movement and recoveries.
• Toe + flat + rear templatese.g. 10' toe – 50mm flat – 27' rear: the toe section helps initiation, the flat calms the stance, the rear supports controlled drive. The most “engineered” of the goalie shapes.

Picking between them: upright/hybrid goalies who live on shuffles lean to long singles; aggressive butterfly goalies who push hard laterally tend to feel the duals and toe-flat designs. Goalie steel also meets goal posts for a living — profiles here get damaged and drift faster, so verification matters even more. Pair this lecture with the goalie hollow lecture in Sharpening 101: platform and bite get tuned together.

Maintenance rhythm: have the profile checked periodically — a quick verification against your recorded spec, not a full re-shape every time. Re-profiling done right removes minimal steel; sloppy re-profiling eats runner life, which is why “controlled removal” is on the legit-job checklist.

New steel = day one again. Replacement runners arrive with the factory 9'/10'. Profile them to your recorded spec before they touch ice, or budget a confused week. Your TSD customer file keeps the spec, so re-running it is a routine visit, not a re-discovery project.

Home sharpeners and your profile: a well-aligned home machine maintains a profile reasonably; a misaligned one erodes it unevenly — and the manufacturer’s own alignment process exists precisely because contact position matters. If you sharpen at home, get the profile verified now and then. The machine can’t tell you your shape changed. The Dude can — it’s in your file.

Likely causes: forward pitch or a toe-heavy balance point — sometimes from a profile, sometimes from a holder change, sometimes from drift.

First move: neutralize pitch before shopping for a new profile family. Fixed feels like: a calm, centered stance with no constant micro-corrections.

Likely causes: too much platform for your style or stage — long contact resisting roll-in. (Youth players: see the 13' trap, lecture 8.)

First move: add front engagement conservatively — one step toward the agile end, pitch neutral while testing. Fixed feels like: turns initiate when you ask, without twitchiness at speed.

Likely causes: not enough stability support — contact too short for your pace, or balance biased too far forward.

First move: add heel support (flatter rear zone) before touching anything else. Fixed feels like: calm straightaways that didn’t cost you your cuts.

Likely causes: left/right mismatch — runner height, contour, or uneven edges from sharpening. Factory steel and drift both cause it.

First move: verify edge level and left/right matching before changing any profile direction. Fixed feels like: both skates loading and releasing identically.

Likely causes: profile drift (lecture 11), a rough sharpening that rounded the shape, new factory steel, or simple steel-height loss after many sharpenings.

First move: profile verification against your recorded spec — a five-minute answer. Rule of thumb: sudden change after a sharpening = check the sharpening; slow change over months = check the profile.