Fitting and adjustment

The One K helmets are available in 3 shell sizes. By using the One K foam liners you can achieve the perfect fit. This system allows the helmet to grow with the young rider. One K helmets are available in 2 shapes, Regular and Long Oval which emphasizes an elongated head from front to back and slightly narrower measurement from side –to – side.

Wearing the wrong shaped or size helmet can lead to increased pressure and discomfort. One K has options for perfect the fit. Please note that both Regular and Long Oval shaped helmets use the same liners. Shape is determined by shell, not the liner.

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HELMETS SIZE CHART

Helmet Size Centimeter Measurement Hat Size
X-Small 51 - 52 cm 6 3/8 - 6 1/2
Small 53 - 54 cm 6 5/8 - 6 3/4
Medium 55 - 56 cm 6 7/8 - 7
Large 57 - 58 cm 7 1/8 - 7 1/4
X-Large 59 - 60 cm 7 3/8 - 7 1/2
XX-Large 61 - 62 cm 7 5/8 - 7 3/4

Junior HELMETS SIZE CHART

Helmet Size Centimeter Measurement Hat Size
X-Small 47 - 48 cm 5 7/8 - 6
Small 49 - 50 cm 6 1/8 - 6 1/4
Medium 51 - 52 cm 6 3/8 - 6 1/2

One K™ liners

Instantly refresh your helmet with the One K removable and washable One K liners. Available in XS – XXL and One K Junior liners are available in XS – M. One K Liners are the easy way to refresh your helmet or size up or down for a helmet that doesn’t quite fit.

One K Helmet Liners
Instantly Refresh Helmet with a Replacement Liner!

Helmet LINERS CONVERSION chart

Stock Helmet Can change helmet to: By replacing with liner sized:
X-Small
(6 3/8 - 6 1/2")
Small
Medium
Small
Medium
Small
(6 5/8 - 6 3/4")
X-Small
Medium
X-Small
Medium
Medium
(6 7/8 - 7")
X-Small
Small
X-Small
Small
Large
(7 1/8 - 7 1/4")
X-Large X-Large
X-Large
(7 3/8 - 1 1/2")
XX-Large XX-Large
XX-Large
(7 5/8 - 7 3/4")
X-Large X-Large

JUNIOR Helmet LINERS CONVERSION chart

Stock Helmet Can change helmet to: By replacing with liner sized:
X-Small Junior
(5 7/8 - 6")
Small Junior
Medium Junior
Small Junior
Medium Junior
Small Junior
(6 1/8 - 6 1/4")
X-Small Junior
Medium Junior
X-Small Junior
Medium Junior
Medium
(6 3/8 - 6 1/2")
X-Small Junior
Small Junior
X-Small Junior
Small Junior
X
×