What the convention comes down to
Every alpine and most touring bindings are sold with a brake width in millimetres — 75, 85, 90, 100, 110, 120 and up. The brake is the pair of arms that spring down when the boot leaves, and they have to straddle the ski. The figure is the widest ski the brake will pass over.
The matching number on the ski is the waist width, the narrowest point, underfoot. Three numbers are sometimes printed on a topsheet — tip, waist, tail — and the middle one is the one that matters here.
The rule is short: the brake must be at least as wide as the waist, and not much wider.
What it does not promise
It does not say anything about release. Brake width and DIN range are independent; a wide brake does not mean a high release value, and the two are chosen on entirely different grounds.
It does not tell you whether the brake can be changed. Many bindings accept brakes of several widths as a spare part; others do not, and on some the spare has disappeared from the catalogue a season after the binding. This is the part of the shelf where a service life is quietly decided, and this site prints what the maker lists.
It does not survive a ski change. A binding remounted on a wider ski may need a new brake as well as new holes.
It is not published by anybody. It is a dimension every maker states and nobody defines, which is why this page sits with the conventions.
What it is read alongside
The binding requirements standard, which covers what the binding must do, and the assembly procedure, which covers how it is set. Neither mentions how wide the ski underneath is.
Where it turns up on this site
Bindings and both ski shelves — and the ski shelf is where the silence is, because the waist width is missing from most listings even when it is the figure that decides the purchase.
This site handles it in one way, consistently. A binding page prints the brake width in millimetres as published, and says which other widths the maker lists as spares. A ski page prints the waist width where the maker publishes it and says it is unpublished where it is not. Neither page guesses the other’s number.
The questions asked most often
How much wider than the ski should the brake be?
Enough to pass, and no more. Makers generally describe a few millimetres over the waist as right; a brake far wider drags in a deep carve and catches on the other ski.
Where do I find the waist of my ski?
Sometimes on the topsheet as the middle figure of three — 130-98-120 is tip, waist, tail in millimetres. Where it is not printed, a caliper at the narrowest point answers it.
Can a brake be bent wider?
Shops do it, within limits, and makers have their own position on it. This site reports what the maker states about brake interchangeability and does not recommend modifications.
Last reviewed 28 September 2026