The best way to determine the correct size of your new Biltwell Bonanza, Gringo, Gringo S, and Lane Splitter Helmet is to try one on. If this isn't possible, follow the steps below and refer to the chart provided to select your correct size.


  1. Using a flexible cloth measuring tape, measure the circumference of your head one inch (2.5cm) above your eyebrows and against the top of your ears around the largest cross-section of your skull. Pull tightly over thick hair to get an accurate measurement.
  2. Find the Helmet Size that corresponds to your Head Measurement on the chart. If your Head Measurement falls between Helmet Sizes, select the larger Helmet Size.

Size chart (Inches)


SizeHead measurementUS Hat size
XS20⅞ – 21⅜6⅝ – 6⅞
S21½ – 226⅞ – 7⅛
M22⅛ – 22⅝7⅛ – 7⅜
L22¾ – 23¼7⅜ – 7⅝
XL23⅜ – 23⅞7⅝ – 7⅞
XXL24 – 24½7⅞ – 8⅛


Size chart (Centimeters)


SizeHead measurementUS Hat size
XS53 - 54.256⅝ – 6⅞
S54.5 - 55.756⅞ – 7⅛
M56 - 57.257⅛ – 7⅜
L57.5 - 58.757⅜ – 7⅝
XL59 - 60.257⅝ – 7⅞
XXL60.5 - 61.757⅞ – 8⅛