Winnebagoland BMX Club Track # 678

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BIKE-TECH

This page will be dedicated to helping parents & racers in their quest for the best information on bikes and gears...
How Do You Know what Bike Size You Should Ride? 
Here is a chart to help guide you.

 

BMX RIDER BIKE SIZING

Rider
Height

Frame
Size

Top Tube
Length

Stem
Length

Bar
Rise

Bar
Width

Crank
Length

Gearing

4'0" & under

Micro-Mini

15"- 15.5"

Mini

2"-2.5"

20"- 21.5"

See Chart
Below

See Chart
Below

4'0"-4'6"

Mini

15.5"- 16.5"

Mini
Mini XL

2"-3.5"

21"- 23"

See Chart
Below

See Chart
Below

4'4"-4'10"

Junior

16"- 17.5"

Mini
Mini XL

3"-4.5"

22"- 24.5"

See Chart
Below

See Chart
Below

4'8"-5'4"

Expert

17"- 18.5"

Pro

4.5"-6"

24"- 26"

See Chart
Below

See Chart
Below

5'2"-5'8"

Expert XL

18"-19"

Pro

6"-7.5"

26"- 27"

See Chart
Below

See Chart
Below

5'6" - 5'10"

Pro

18.5"- 19.5"

Pro
Pro XL

7"-8"

27"- 28"

See Chart
Below

See Chart
Below

5'10"-6'1"

Pro XL

19"-21"

Pro
Pro XL

7"-8"

17"- 28"

See Chart
Below

See Chart
Below

6' & over

Pro XXL

20.5" & over

Pro XL
Pro XXL

7"-8"

28"- ?"

See Chart
Below

See Chart
Below

 

What is the Correct Wheel Size?

Wheel Sizes

MAXIMUM RIDER WEIGHT
RIM WIDTH
0 – 85#
Sew Ups
86 – 100
20 x 1-1/8"
101 – 120
20 x 1-3/8"
121 – 150
20 x 1.50"
151 – 200
20 x 1.75"


 What Crank Size Do You Need? 

CRANK SIZING CHART

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

What Gear Should You Run?
 Most riders regardless of class seem to prefer a rotation of approximately 53"
To figure your rotation here is the formula.
** Sprocket divided by Freewheel times Tire diameter **

 

Gear Charts

  20" X 1.75" Gear Chart

Sprocket

34

35

36

37

38

39

40

41

Freewheel 14

47.4

48.7

50.2

51.6

53.0

54.4

55.7

57.1

Freewheel 15

44.3

45.4

46.0

48.1

49.4

50.7

52.0

53.3

Freewheel 16

41.5

42.7

43.9

45.1

46.3

47.5

48.8

50.0

Freewheel 17

39.0

40.2

41.3

42.5

43.6

44.7

45.9

47.0

Freewheel 18

36.8

37.8

39.0

40.1

41.2

42.3

43.3

44.4
   

Sprocket

42

43

44

45

46

47

48

  

Freewheel 14

58.5

59.9

61.9

62.7

64.1

65.5

66.9

Freewheel 15

54.6

55.9

57.2

58.5

59.8

61.1

62.4

Freewheel 16

51.2

52.4

53.7

54.9

56.1

57.3

58.5

Freewheel 17

48.2

49.4

50.5

51.7

52.8

53.9

55.1

Freewheel 18

45.5

46.6

47.7

48.8

49.9

51.0

52.0

 

20" X 1.50" Gear Chart

Sprocket

34

35

36

37

38

39

40

41

Freewheel 14

46.8

48.1

49.5

50.9

52.3

53.6

55.0

56.4

Freewheel 15

43.6

44.9

46.2

47.4

48.8

50.1

51.3

52.8

Freewheel 16

40.9

42.1

43.3

44.5

45.7

46.9

48.1

49.3

Freewheel 17

38.5

39.6

40.8

41.9

43.1

44.1

45.2

46.4

Freewheel 18

36.4

37.4

38.5

39.6

40.6

41.7

42.8

43.9
   

Sprocket

42

43

44

45

46

47

48

  

Freewheel 14

57.5

59.1

60.5

61.8

63.2

64.6

66.0

Freewheel 15

53.9

55.2

56.5

57.7

59.1

60.2

61.6

Freewheel 16

50.5

51.7

52.9

54.1

55.3

56.5

57.7

Freewheel 17

47.5

48.7

49.8

51.0

52.2

53.1

54.3

Freewheel 18

44.9

46.0

47.0

48.1

49.2

50.3

51.3

 

20" X 1.3/8" Gear Chart

Sprocket

34

35

36

37

38

39

40

41

Freewheel 14

51.0

52.5

54.0

55.5

57.0

58.5

60.0

61.5

Freewheel 15

47.6

49.0

50.4

51.6

53.2

54.6

56.0

57.4

Freewheel 16

44.6

45.9

47.3

48.6

49.9

51.2

52.5

53.9

Freewheel 17

42.0

43.2

44.5

45.7

47.0

48.2

49.4

50.7

Freewheel 18

39.7

40.7

42.0

43.2

44.4

45.5

46.7

47.9

Sprocket

42

43

44

45

46

47

48

Freewheel 14

63.0

64.5

66.0

67.5

69.0

70.5

72.0

Freewheel 15

58.8

60.2

61.6

63.0

64.4

65.8

67.2

Freewheel 16

55.2

56.5

57.8

59.1

60.4

61.7

63.0

Freewheel 17

51.9

53.2

54.4

55.6

56.9

58.1

59.3

Freewheel 18

49.0

50.2

51.4

52.5

53.7

54.9

56.0

 

20" X 1.1/8" Gear Chart

Sprocket

 34 35 36 37 38 39 40 41

Freewheel 14

48.6

50.0

51.4

52.8

54.3

55.7

57.1

58.6

Freewheel 15

45.3

46.7

48.0

49.3

50.7

52.0

53.3

54.7

Freewheel 16

42.5

43.8

45.0

46.2

47.5

48.7

50.0

51.2

Freewheel 17

40.0

41.2

42.3

43.5

44.7

45.9

47.0

48.2

Freewheel 18

37.7

38.8

40.0

41.1

42.2

43.3

44.4

45.6
   

Sprocket

 42 43 44 45 46 47 48  

Freewheel 14

60.0

61.4

62.8

64.3

65.7

67.1

68.6

Freewheel 15

56.0

57.3

58.7

60.0

61.3

62.7

64.0

Freewheel 16

52.5

53.7

55.0

56.2

57.5

58.7

60.0

Freewheel 17

49.4

50.6

51.8

52.9

54.1

55.3

56.5

Freewheel 18

46.7

47.8

48.9

50.0

51.1

52.2

53.3

 

24" X 1.75" Gear Chart

 

Sprocket

34

35

36

37

38

39

40

41

Freewheel 14

58.3

60.0

61.7

63.3

65.0

66.9

68.6

70.3

Freewheel 15

54.4

56.0

57.6

59.3

60.7

62.4

64.1

65.5

Freewheel 16

51.0

52.5

54.0

55.5

57.0

58.5

60.0

61.4

Freewheel 17

48.0

49.4

50.0

52.2

53.6

55.1

56.5

57.9

Freewheel 18

45.3

46.5

48.0

49.4

50.7

52.0

53.3

54.7
   

Sprocket

42

43

44

45

46

47

48

  

Freewheel 14

72.0

73.7

75.3

77.0

78.9

80.6

82.3

Freewheel 15

67.2

68.9

70.3

72.0

73.7

75.1

76.8

Freewheel 16

63.1

64.5

66.0

67.4

69.1

70.5

72.0

Freewheel 17

59.3

60.7

62.1

63.6

65.0

66.2

67.7

Freewheel 18

56.0

57.3

58.5

60.0

61.4

62.6

64.1

 

24" X 1.50" Gear Chart

 

Sprocket

34

35

36

37

38

39

40

41

Freewheel 14

55.9

57.5

59.1

60.7

62.3

64.2

65.8

67.4

Freewheel 15

52.1

53.7

55.2

56.7

58.2

59.8

61.3

62.8

Freewheel 16

48.4

50.3

51.8

53.2

54.6

56.0

57.5

58.9

Freewheel 17