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F01003800-110-204

509 Altitude 2.0 Carbon Fiber Helmet

Size Guide
509 Sizing Chart

How to Measure

Head: Measure circumference of head just above top of ears and eyebrows.

Waist: Measure under arms, around the fullest part of the chest. Keep tape level across back, comfortably loose.

Chest: With arm fully extended, measure center back of neck at the spine to the wrist bone.

Chest: Measure under arms, around the fullest part of the chest. Keep tape level across back, comfortably loose.

Inseam: Without shoes, measure inside of leg, from groin to floor.

Helmet Sizing US Hat Size Inches Centimeters
X-Small

6 5/8 - 6 3/4

20 7/8 - 21 1/8

53 - 54

Small

6 7/8 - 7

21 5/8 - 21 7/8

55 - 56

Medium

7 1/8 - 7 1/4

22 1/2 - 22 5/8

57 - 58

Large

7 3/8 - 7 1/2

23 1/4 - 23 1/2

59 - 60

X-Large

7 5/8 - 7 3/4

24 - 24 1/4

61 - 62

2X-Large

8

24 3/4 - 25

63 - 64

3X-Large

8 3/4

25 1/4 - 25 3/4

64 - 65

4X-Large

9

26 - 26 1/4

66 - 67


Youth Helmets US Hat Size Inches Centimeters

Youth Small

6

18 1/8 - 18 7/8

47 - 48

Youth Medium

6 1/8 - 6 1/4

19 1/4 - 19 5/8

49 - 50

Youth Large

6 3/8 - 6 1/2

20 - 20 1/2

51 - 52


Men's Sizing X-Small Small Medium Large X-Large 2X-Large 3X-Large

Chest

34 - 36

36 - 38

39 - 41

42 - 44

45 - 47

48 - 50

52 - 54

Sleeve

27

28

30

32

34

36

36

Waist

30

32

34

36

38

40

42

Inseam

29

30

31

32

33

34

34

Short Inseam

29

29

30

30

31

31

31

Tall Inseam

34

34

35

35

36

36

36

Gloves

7

8

9

10

11

12

13


Women's Sizing X-Small Small Medium Large X-Large 2X-Large

Chest

30

32

34

36

38

40

Sleeve

24

26

28

30

32

34

Waist

28

30

32

34

36

38

Inseam

29

30

32

34

36

38

Gloves

5

6

7

8

9

n/a

5 items left

509 Altitude 2.0 Carbon Fiber Helmet

Reinvented to ride even harder, the second generation of the bestselling 509 Altitude series unleashes a whole new animal. Leading the charge is the 509 Altitude 2.0 Carbon Fiber Helmet with a new hand lay-up carbon composite construction that’s lighter, stronger, and straight-up sleeker than anything before it. For those who like to get aggressive, it includes the Fidlock® magnetic strap buckle for easy one-handed ope. . . Show More >

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