Alpine skiing's four disciplines are four points on a single line

Ask what separates a slalom from a giant slalom and the usual answer is that the gates are closer together. That is true, and it is not how the rule says it.

The International Ski and Snowboard Competition Rules do not specify a number of gates for any of the three technical disciplines. They specify a ratio: how many direction changes a course must contain, expressed as a percentage of its vertical drop.

For slalom, at all FIS events: 30 to 35 per cent of the vertical drop, plus or minus three direction changes.

Reference The slalom requirement of 30 to 35 per cent of the vertical drop, plus or minus three direction changes, from Article 801.2.4.

For giant slalom: 11 to 15 per cent of the vertical drop in metres.

Reference The giant slalom requirement of 11 to 15 per cent of the vertical drop, from Article 901.2.4.

For super-G, a minimum only: 6 per cent of the vertical drop at the Olympic Winter Games, World Championships, World Junior Championships and Continental Cup level, and 7 per cent at FIS-level events.

Reference The super-G minimum of 6 per cent of the vertical drop at Olympic, World Championship, World Junior Championship and Continental Cup level and 7 per cent at FIS level, from Article 1001.3.4.

And for downhill, nothing. The ICR’s own summary table gives the downhill’s number of gates as as required.

Reference That the downhill’s number of gates is given as “as required” in the ICR’s check-list for vertical drop, number of gates and direction changes.

One axis, four points

Put the densities beside each other and the four events resolve into a single continuum.

The numbers behind this chart

Row	Per cent of the vertical drop, at the top level of competition	Detail
Super-G	6	A minimum only: 6 per cent of the vertical drop at Olympic, World Championship, World Junior and Continental Cup level; 7 per cent at FIS level — Article 1001
Giant slalom	11 to 15	Minimum vertical drop of 300 m at the Olympic Winter Games, World Championships and World Cup for both women and men — Article 901
Slalom	30 to 35	Plus or minus three direction changes — Article 801

Source FIS, International Ski and Snowboard Competition Rules, Book IV, Edition 5 July 2024, Articles 801.2.4, 901.2.4 and 1001.3.4.
Method Values as stated in the rule for the top level of competition. Super-G states a minimum only and is plotted as a single value. Slalom's additional tolerance of plus or minus three direction changes is not expressible as a percentage and is noted rather than plotted. Downhill is excluded because the rule states no requirement.

And now the second half of the pattern, which runs the other way.

The numbers behind this chart

Row	Metres of vertical drop — end caps mark the permitted range	Detail
Downhill	800 to 1,100	women 450–800 m — Article 701
Super-G	400 to 650	women 400–600 m — Article 1001
Giant slalom	300 to 450	women 300–400 m — Article 901
Slalom	180 to 220	women 140–220 m — Article 801

Source FIS, International Ski and Snowboard Competition Rules, Book IV, Edition 5 July 2024, Articles 701.1.1, 801.1.1, 901.1 and 1001.1.1.
Method Men's ranges at the Olympic Winter Games, FIS World Ski Championships and FIS World Cup. Downhill's minimum may fall to 750 m in exceptional cases; the standard figure is plotted.

The two charts are mirror images. The discipline with the most turns has the least descent; the one with the most descent has no turn requirement at all. Slalom’s 180–220 metres of drop carries 30–35 per cent turn density; downhill’s 800–1,100 metres carries none.

That is what makes alpine racing one sport rather than four. The events are not different games played on mountains; they are the same game sampled at four densities, and FIS has written the sampling parameter directly into the rulebook.

What the gates do to fill in the shape

The gate specifications track the same axis, and they explain why the disciplines feel so different at the same density.

Slalom gates must be at least 4 m and at most 6 m wide, with successive turning poles 6 to 13 m apart. Giant slalom gates are 4 to 8 m wide, with successive turning poles no less than 10 m apart. Super-G open gates are 6 to 8 m wide and vertical gates 8 to 12 m, with turning poles at least 25 m apart.

Reference The gate widths and turning-pole spacings for slalom (Article 801.2.3), giant slalom (Article 901.2.3) and super-G (Articles 1001.3.3 and 1001.3.4).

Minimum spacing between turning poles: 6 m, then 10 m, then 25 m. The gates get wider as they get further apart, which is the geometric requirement for a turn of larger radius at higher speed.

Slalom then adds constructions the other disciplines do not have: hairpins and vertical combinations, whose gates sit between 0.75 m and 1 m apart, and delayed gates at 12 to 18 m.

Reference The spacings within hairpin and vertical combinations, and for delayed gates, from Article 801.2.3.

Three-quarters of a metre. That is the tightest dimension anywhere in alpine racing, and it exists only in slalom.

What this dataset cannot tell you

Four caveats, and they are recorded in the compiled table rather than left to the chart.

These are permitted limits at one level of competition. Continental Cup, FIS-level, youth and Entry League races carry different ranges, and the rule states each separately — a youth slalom, for example, runs at 32 to 38 per cent rather than 30 to 35.

Slalom’s tolerance of plus or minus three direction changes cannot be expressed as a percentage, and super-G states a minimum with no ceiling. Both are noted rather than flattened into a range.

Downhill’s absence is an absence of specification and not a value of zero. A downhill course has gates — the rule specifies their panels, colours and construction in detail — but it does not specify how many.

And a permitted range describes a rule, not a course. Every FIS course is individually approved, and only the FIS Council may grant exceptions to the prescribed technical data.

Reference That all competitions must take place on FIS-approved courses complying with the technical requirements of Articles 701, 801, 901 and 1001, and that only the FIS Council can grant exceptions or deviations from the prescribed technical data, from Article 650.1.

Why parameterise at all

The alternative would have been to specify courses the way most sports specify fields: a fixed length, a fixed number of gates, a fixed layout. Alpine skiing cannot do that, because it does not build its venues. It uses mountains, and no two mountains are alike.

So FIS specifies the one thing that can be held constant across different terrain — the rate at which a skier must change direction — and lets the vertical drop and the ground supply the rest. A 200-metre slalom and a 220-metre slalom are the same discipline because they carry the same turn density, not because they are the same shape.

It is the same problem golf answers by declining to specify anything, and cycling answers by fixing a track’s length while leaving its banking free. Alpine skiing’s answer is the most quantitative of the three: pick the ratio that defines the event, write it into the rulebook, and let every mountain solve it differently.