Alpinestars Bionic Plus Youth Knee Protector - Black

Alpinestars Bionic Plus Youth Knee Protector - Black

Alpinestars Bionic Plus Youth knee and shin guards carry CE certification to EN 1621-1 Level 1, built around kids' leg proportions rather than a scaled-down adult shell. The Cell hard-shell cap covers the knee and extends onto the upper shin, with extra venting cut through the shell itself. A multi-layer build combines stretch mesh against the skin, thermoform padding, viscoelastic foam, and rigid OSG (Outer Shell Grid) sections — a construction pulled from motorsport protection. Two straps, one above the knee and a second routed ergonomically below it, keep the guard in place on impact, while a flexion channel through the shell lets the knee bend through its full range. The pair is built for cycling, BMX, and enduro riding, wherever a kid needs real impact protection rather than soft padding alone.

OSG (Outer Shell Grid) — motorsport-derived, lightweight build

OSG (Outer Shell Grid) builds the hard sections of the guard from a grid of specially developed polymers instead of a single solid plastic cap. Alpinestars uses the same principle on protection built for motocross and road racing, where the trade-off between weight, protection, and mobility is identical. The grid structure holds impact protection at a noticeably lower weight than a solid cap, and the gaps in the structure let air pass through — something a classic foam pad can't do. The guard stays flexible through the bend instead of acting like a rigid shield strapped to the leg.

What does EN 1621-1 Level 1 certification mean?

EN 1621-1 measures how much impact force a guard transmits through to the body. Level 1 allows a mean residual force of up to 35 kN, the stricter Level 2 caps it at 20 kN — Bionic Plus Youth is certified to Level 1, the standard tier for knee guards in cycling and motocross alike. The test runs against an instrumented anvil, not living tissue, but the residual force figure correlates with injury risk on impact.

Flexion channel and dual strap closure — unrestricted movement

A flexion channel cuts through the hard shell right at the knee joint, following its natural arc of movement. On a full bend — pedaling stroke, crouching off a drop — the shell doesn't dig into the back of the knee or ride up the leg. Two hook-and-loop straps, one above the knee and a second routed ergonomically below it, hold position on impact, where a single-strap design would slip. The asymmetric cut also follows the shape of the leg, so the guard doesn't twist out of place on longer rides.

3D mesh and vented panels — airflow even at skin contact

The skin-side panel is stretch 3D mesh, not smooth foam — the structure opens tiny air channels between the material and the skin, so air keeps moving even at the point of direct contact. Vented panels in the hard shell add extra venting where heat builds up most, typically above and below the knee joint. For a kid riding through an intense summer afternoon, that means noticeably less sweat build-up under the guard compared to a closed foam design.

Sizing and who it fits

Bionic Plus Youth comes in two sizes, S/M and L/XL — both built around kids' leg proportions, not scaled down from the adult Bionic range. The fit runs snug, so on a borderline thigh/calf measurement we'd size up rather than down, so the dual-strap closure still sits right as the leg grows through the season. The flexible OSG build and flexion channel keep the full range of motion even in the larger size, so the knee doesn't lose mobility on a full crouch.

Full technical specifications are available in the Specifications tab on the product page.

Frequently Asked Questions

What's the difference between Level 1 and Level 2 under EN 1621-1?

Level 1 allows a mean residual force of up to 35 kN, Level 2 caps it at 20 kN — the lower the number, the less impact force reaches the body. Bionic Plus Youth is certified to Level 1, the standard tier for kids' knee guards in cycling. Level 2 guards tend to run stiffer and heavier, which is why they show up more often on motocross or DH-specific protection, where impacts are harder.

Does it protect the shin too, or just the knee?

The hard shell extends from the knee onto the upper shin, covering ground a knee-only cap misses. Full coverage details are in the Specifications tab.

How do I choose between S/M and L/XL?

Both sizes are built for kids, not cut down from the adult range — S/M suits smaller kids with a narrower thigh/calf, L/XL suits bigger kids or younger teens. The fit runs snug, so on a borderline measurement we'd size up.