Kit Sizing and Fit Basics: Helmets, Shoes, Pads & Women's Fit

A separate tool, a separate kind of fit

The Kit Builder covers rider gear — helmets, shoes, apparel, and protection — completely separately from the bike compatibility engine. Nothing you pick in the Kit Builder can turn a bike build's verdict red, yellow, or green, because the two are intentionally isolated from each other. Everything here is about how gear fits you, not how parts fit a bike.

Helmet fit: shell size plus a rotational system

Helmet sizing (S/M/L and so on) is sized to head circumference, and that sizing runs genuinely differ between brands — a size Medium from one maker and a size Medium from another won't necessarily fit the same head the same way, so it's worth checking a brand's own size chart against your own measured circumference rather than assuming your size carries over.

Separately from shell size, many helmets carry a rotational-impact system — MIPS is the most common, a slip-plane liner designed to reduce rotational force transmitted to the head in an angled impact. The catalog only tags a helmet's rotational system when it's genuinely part of that specific SKU's identity — some makers build their own proprietary rotational tech under a different name entirely, and in those cases the field is deliberately left blank rather than mislabeled as MIPS just because MIPS is the most common option. That means an absent rotational tag on a given helmet means the catalog doesn't have a confirmed tag for it — it is not a claim that the helmet has no rotational protection at all.

Helmet types and certifications

Helmets are cataloged by type — half-shell (open-face, trail-oriented), full-face (complete chin and face coverage, enduro/DH-oriented), and convertible (a half-shell with a removable chin bar, covering both uses with one shell). Where a certification badge like CPSC, EN 1078, or ASTM F1952 is shown, it's because a sourced manufacturer page cited that specific standard by number for that helmet — the same conservative policy the rest of the catalog uses for provenance. A helmet's real-world certification may be broader than what's shown if the maker's own page only cites some of its standards by name rather than number; the badge reflects what could be confirmed, not necessarily everything the helmet actually meets.

Shoe styles: flat vs. clipless

Every shoe in the catalog is tagged with a sole style — flat (a grippy, pin-compatible flat sole paired with flat pedals) or clipless (a cleat-recessed sole that locks into a clipless pedal system). This is purely a personal riding-style choice, not a compatibility question the way a pedal's own thread size might be — 9/16" pedal threads fit every crank regardless of style. Closure systems (laces, BOA dials, velcro straps) are a separate fit-tuning detail layered on top of sole style, and shoe sizing runs vary by brand and sometimes by region (US vs. EU numbering) — check each specific model's own size chart rather than assuming your usual size carries over.

Pad certifications: reading EN 1621 levels

Knee and elbow pads carry impact-protection certifications under the EN 1621-1 standard (limb impact protectors), which defines two certified levels: Level 1 is the standard's base certified impact-protection threshold, and Level 2 is a higher-rated threshold that passes a more demanding impact test. A higher level generally means a bulkier, firmer pad; a Level 1 pad isn't uncertified or unsafe, it's simply certified to the lower of the standard's two tiers. As with helmets, the catalog only tags a specific certification level when a sourced manufacturer page states it by standard number — the same honest-provenance policy applied consistently across every protective category.

Women's-specific fit lines

Apparel, gloves, and some shoes may carry a women's-specific fit tag, meaning the manufacturer sells that item as a genuinely distinct pattern or last — different cut, sizing progression, or proportions — rather than simply the same unisex item in smaller sizes. This tag is only applied when a manufacturer's own page states the item is women's-specific; the catalog has corrected this tag in the other direction too, when a closer look at a maker's page showed an item was actually sold as a single unisex fit rather than a dedicated women's cut. Absence of the tag means either the item is genuinely unisex, or that a women's-specific version wasn't confirmed — not a claim that no women's option exists anywhere from that brand.

How BuildMyMTB treats all of this

Every field described above is purely descriptive shopping information for the Kit Builder — sole style, rotational system, certification level, and fit line all help you pick gear that suits your riding and your body, but none of them are checked against your bike build in any way. The Kit Builder's own data still goes through the same kind of schema validation as the bike catalog (see the What "Verified" Actually Means on This Site guide for how that provenance bar works generally), just scoped entirely to gear rather than bike parts.

Practical takeaways

• Measure your own head circumference and check it against each specific helmet model's own size chart — sizing isn't consistent across brands.
• A blank rotational-system field on a helmet means "not confirmed," not "none" — some brands run their own named tech instead of MIPS.
• Choose flat vs. clipless shoes based on your own riding style and pedal preference — it has no bearing on any other part of the bike.
• A Level 1 EN 1621-1 pad is certified, just to the standard's lower tier — Level 2 is the higher, bulkier-typically tier, not a sign Level 1 is unsafe.
• A women's-specific tag means a genuinely distinct pattern the maker sells that way — check the specific model if you're unsure which fit you're looking at.