1. Achieve the perfect fit by measuring your head circumference correctly.

2. Watch the video below to see how to measure your head correctly.

3. VIDEO: How To Measure For A Bike Helmet

4. On the chart below, find the helmet model that you are interested in, then find your head measurement to see which size you need.

100Percent Bike Helmet Size Charts

100Percent Mountain Bike Helmet Size Chart

Model	XS	S	M	L	XL	XXL
Aircraft	53 – 54cm	55 – 56cm	57 – 58cm	59 – 60cm	61 – 62cm	63 – 64cm
Aircraft	20⅞” – 21¼”	21⅝” – 22″	22½” – 22⅞”	23¼” – 23⅝”	24″ – 24⅜ “	24¾”- 25¼”
Aircraft Carbon MIPS	53 – 54cm	55 – 56cm	57 – 58cm	59 – 60cm	61 – 62cm	63 – 64cm
Aircraft Carbon MIPS	20⅞” – 21¼”	21⅝” – 22″	22″ – 22⅞”	23¼” – 23⅝”	24″ – 24⅜ “	24¾”- 25¼”
Status	53 – 54cm	55 – 56cm	57 – 58cm	59 – 60cm	61 – 62cm	63 – 64cm
Status	20⅞” – 21¼”	21⅝” – 22″	22″ – 22⅞”	23¼” – 23⅝”	24″ – 24⅜ “	24¾”- 25¼”
Trajecta		52 – 56cm	56 – 58cm	58 – 61cm	61 – 64cm
Trajecta		20½” – 22″	22″ – 22⅞”	22⅞” – 24″	24″ – 25¼”

Model	XS-Small	S/M	L/XL
Altec	50 – 55cm	55 – 59cm	59 – 63cm
Altec	19⅝ “- 21⅝ “	21⅝” – 23¼”	23¼” – 24¾”

Model	Y-Small	Y-Medium	Y-Large
Status	47 – 48cm	49 – 50cm	51 – 52cm
Status	18½” – 18⅞”	19¼” – 19⅝”	20⅛” – 20½”

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