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Rider Sizes and Gearing Charts for BMX racing bicycles.

Rider Size and Bike Frame Guidelines

Rider Height

Frame Size

Top Tube

Stem

Bar Rise

Bar Width

Cranks

Gearing

4'0"& under

Micro-Mini

15"-16"

Mini

2"-2.5"

20"-22.5"

150-160mm

41-43/16

4'0"-4'6"

Mini

16"-17"

Mini-Mini XL

2"-3.5"

21"-23.5"

155-165mm

41-43/16

4'4"-4'10"

Junior

17"-18.5"

Mini XL-Pro

3"-5"

22"-25"

160-175mm

42-43/16

4'8"-5'4"

Expert

18.5"-19.5"

Pro

5"-7"

25.5"-27"

170-175mm

42-43/16

5'4"-5'10"

Pro

20"-20.5"

Pro-Pro XL

7"-8"

27"-28"

175-180mm

43-44/16

5'10"& over

Pro XL-XXL

20.5"& over

Pro XL-XXL

7"-8"

28.5" (max)

180-185mm

44/16&over

Crank Length Guidelines

Riders Inseam

20"

21"

22"

23"

24"

25"

26"

Crank Length

140mm

145mm

150mm

155mm

160mm

162mm

166mm

Riders Inseam

27"

28"

29"

30"

31"

32"

34"

Crank Length

171mm

175mm

177mm

180mm

182mm

185mm

190mm

Wheel Size for Rider Weight Guidelines

 

Max Rider Weight

Rim Width

 

 

Up to 65 lbs

1.00"

 

 

50 to 90 lbs

1 1/8"

 

 

85 to 120 lbs

1 3/8"

 

 

115 to 150 lbs

1.50"

 

 

140 lbs and Up

1.75"

 

Rear Tire Size and Rollout in Inches (varies with Brand, model)

20" X 1.75" GEAR CHART

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

47.4

48.7

50.2

51.6

53.0

54.4

55.7

57.1

58.5

59.9

61.9

62.7

64.1

Freewheel 15

44.3

45.4

46.0

48.1

49.4

50.7

52.0

53.3

54.6

55.9

57.2

58.5

59.8

Freewheel 16

41.5

42.7

43.6

45.1

46.3

47.5

48.8

50.0

51.2

52.4

53.7

54.9

56.1

Freewheel 17

39.0

40.2

41.3

42.5

43.6

44.7

45.9

47.0

48.2

49.4

50.5

51.7

52.8

Freewheel 18

36.8

37.8

39.0

40.1

41.2

42.3

43.3

44.4

45.5

46.6

47.7

48.8

49.9

20" X 1.50" GEAR CHART

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

46.8

48.1

49.5

50.9

52.3

53.6

55.0

56.4

57.5

59.1

60.5

61.8

63.2

Freewheel 15

43.6

44.9

46.2

47.4

48.8

50.1

51.3

52.8

53.9

55.2

56.5

57.7

59.1

Freewheel 16

40.9

42.1

43.3

44.5

45.7

46.9

48.1

49.3

50.5

51.7

52.9

54.1

55.3

Freewheel 17

38.5

39.6

40.8

41.9

43.1

44.1

45.2

46.4

47.5

48.7

49.8

51.0

52.2

Freewheel 18

36.4

37.4

38.5

39.6

40.6

41.7

42.8

43.9

44.9

46.0

47.0

48.1

49.2

20" x 1 3/8" GEAR CHART

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

51.0

52.5

54.0

55.5

57.0

58.5

60.0

61.5

63.0

64.5

66.0

67.5

69.0

Freewheel 15

47.6

49.0

50.4

51.6

53.2

54.6

56.0

57.4

58.8

60.2

61.6

63.0

64.4

Freewheel 16

44.6

45.9

47.3

48.6

49.9

51.2

52.5

53.9

55.2

56.5

57.8

59.1

60.4

Freewheel 17

42.0

43.2

44.5

45.7

47.0

48.2

49.4

50.7

51.9

53.2

54.4

55.6

56.9

Freewheel 18

39.7

40.7

42.0

43.2

44.4

45.5

46.7

47.9

49.0

50.2

51.4

52.5

53.7

20" X 1 1/8" GEAR CHART

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

48.6

50.0

51.4

52.8

54.3

55.7

57.1

58.6

60.0

61.4

62.8

64.3

65.7

Freewheel 15

45.3

46.7

48.0

49.3

50.7

52.0

53.3

54.7

56.0

57.3

58.7

60.0

61.3

Freewheel 16

42.5

43.8

45.0

46.2

47.5

48.7

50.0

51.2

52.5

53.7

55.0

56.2

57.5

Freewheel 17

40.0

41.2

42.3

43.5

44.7

45.9

47.0

48.2

49.4

50.6

51.8

52.9

54.1

Freewheel 18

37.7

38.8

40.0

41.1

42.2

43.3

44.4

45.6

46.7

47.8

48.9

50.0

51.1

24" X 1.75" GEAR CHART (Cruiser)

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

58.3

60.0

61.7

63.3

65.0

66.9

68.6

70.3

72.0

73.7

75.3

77.0

78.9

Freewheel 15

54.4

56.0

57.6

59.3

60.7

62.4

64.1

65.5

67.2

68.9

70.3

72.0

73.7

Freewheel 16

51.0

52.5

54.0

55.5

57.0

58.5

60.0

61.4

63.1

64.5

66.0

67.4

69.1

Freewheel 17

48.0

49.4

50.0

52.2

53.6

55.1

56.5

57.9

59.3

60.7

62.1

63.6

65.0

Freewheel 18

45.3

46.5

48.0

49.4

50.7

52.0

53.3

54.7

56.0

57.3

58.5

60.0

61.4

24" X 1 1/8" GEAR CHART (Cruiser)

Chain wheels

34

35

36

37

38

39

40

41

42

43

44

45

46

Freewheel 14

54.9

56.5

58.1

59.7

61.3

63.1

64.7

66.3

67.9

69.4

71.0

72.6

74.4

Freewheel 15

51.3

52.8

54.3

55.8

57.3

58.8

60.3

61.8

63.3

64.9

66.3

67.9

69.4

Freewheel 16

48.1

49.5

50.9

52.3

53.7

55.1

56.6

57.9

59.5

60.8

62.2

63.9

65.1

Freewheel 17

45.2

46.6

47.9

49.3

50.6

51.9

53.2

54.6

55.9

57.2

58.6

59.9

61.3

Freewheel 18

42.7

43.9

45.2

46.6

47.7

49.1

50.3

51.5

52.8

54.0

55.3

56.6

57.9

 

Remember: Gearing and ergonomics are important, however don't forget to practice and train for success.