Troy Lee Designs D4 Carbon Mips Full Face MTB Mountain Bike Helmet











D4 reigns king atop downhill podiums and BMX events across the globe. Available in carbon, composite and polyacrylite. Details are what makes the D4 the most coveted full-face in mountain biking. Prioritizing safety while balancing weight through premium construction and materials, D4 incorporates Mips® protection with an EPP chin bar and anatomical cheek pads with emergency release.
Key Features:
- Mips® C2 Rotational Impact Brain Protection System
- UD carbon fiber shell
- Three shell sizes to more accurately fit a variety of head sizes and rider ages
- Anatomical "3D” contoured cheek pads with emergency release system for EMS responders
- Removable snap-in, washable comfort liner with Coolmax® and Dri-lex® moisture-wicking materials
- Super light titanium D-rings
- 1000g
- CPSC 1203*, CE EN1078*, ASTM F1952-DH, ASTM 2032-BMX. *Varies by regional standards
Occasionally, without notice, manufacturers change product design and/or specifications.
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Troy Lee Designs D4 Helmet Size Guide
How to measure
To find the circumference of your head, place a tape measure in the centre of your forehead, wrap it around above your ears and around the back of your head. If there's a slight difference between two different sizes, always go for the tighter size.

D4 Helmet Size Chart
|
Size |
XS |
S |
M |
L |
XL |
XXL |
|
Circumference (cm) |
53 - 54 |
55 - 56 |
57 - 58 |
58 - 59 |
60 - 61 |
62 - 63 |
|
Circumference (Inch) |
20 7/8 - 21 1/4 |
21 5/8 – 22 |
22 3/8 – 22 3/4 |
22 ¾ - 23 1/4 |
23 5/8 – 24 |
24 3/8 – 24 3/4 |
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