S P R O C K E T -S I Z E

C
H
A
I
N
R
I
N
G

S
I
Z E

 

.

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

57

128.3

118.4

109.9

102.6

96.2

90.5

85.5

81.0

77.0

73.3

70.0

66.9

64.1

61.6

59.2

57.0

55.0

53.1

51.3

56

126.0

116.3

108.0

100.8

94.5

88.9

84.0

79.6

75.6

72.0

68.7

65.7

63.0

60.5

58.2

56.0

54.0

52.1

50.4

55

123.8

114.2

106.1

99.0

92.8

87.4

82.5

78.2

74.3

70.7

67.5

64.6

61.9

59.4

57.1

55.0

53.0

51.2

49.5

54

121.5

112.2

104.1

97.2

91.1

85.8

81.0

76.7

72.9

69.4

66.3

63.4

60.8

58.3

56.1

54.0

52.1

50.3

48.6

53

119.3

110.1

102.2

95.4

89.4

84.2

79.5

75.3

71.6

68.1

65.0

62.2

59.6

57.2

55.0

53.0

51.1

49.3

47.7

52

117.0

108.0

100.3

93.6

87.8

82.6

78.0

73.9

70.2

66.9

63.8

61.0

58.5

56.2

54.0

52.0

50.1

48.4

46.8

51

114.8

105.9

98.4

91.8

86.1

81.0

76.5

72.5

68.9

65.6

62.6

59.9

57.4

55.1

53.0

51.0

49.2

47.5

45.9

50

112.5

103.9

96.4

90.0

84.4

79.4

75.0

71.1

67.5

64.3

61.4

58.7

56.3

54.0

51.9

50.0

48.2

46.5

45.0

49

110.3

101.8

94.5

88.2

82.7

77.8

73.5

69.6

66.2

63.0

60.1

57.5

55.1

52.9

50.9

49.0

47.3

45.6

44.1

48

108.0

105.9

92.6

86.4

81.0

76.2

72.0

68.2

64.8

61.7

58.9

56.3

54.0

51.8

49.8

48.0

46.3

44.7

43.2

47

105.8

97.6

90.6

84.6

79.3

74.6

70.5

66.8

63.5

60.4

57.7

55.2

52.9

50.8

48.8

47.0

45.3

43.8

42.3

46

103.5

95.5

88.7

82.8

77.6

73.1

69.0

65.4

62.1

59.1

56.5

54.0

51.8

49.7

47.8

46.0

44.4

42.8

41.4

45

101.3

93.5

86.8

81.0

75.9

71.5

67.5

63.9

60.8

57.9

55.2

52.8

50.6

48.6

46.7

45.0

43.4

41.9

40.5

44

99.0

91.4

84.9

79.2

74.3

69.9

66.0

62.5

59.4

56.6

54.0

51.7

49.5

47.5

45.7

44.0

42.4

41.0

39.6

43

96.8

89.3

82.9

77.4

72.6

68.3

64.5

61.1

58.1

55.3

52.8

50.5

48.4

46.4

44.7

43.0

41.5

40.0

38.7

42

94.5

87.2

81.0

75.6

70.9

66.7

63.0

59.7

56.7

54.0

51.5

49.3

47.3

45.4

43.6

42.0

40.5

39.1

37.8

41

92.3

85.2

79.1

73.8

69.2

65.1

61.5

58.3

55.4

52.7

50.3

48.1

46.1

44.3

42.6

41.0

39.5

38.2

36.9

40

90.0

83.1

77.1

72.0

67.5

63.5

60.0

56.8

54.0

51.4

49.1

47.0

45.0

43.2

41.5

40.0

38.6

37.2

36.0

39

87.8

81.0

75.2

70.2

65.8

61.9

58.5

55.4

52.7

50.1

47.9

45.8

43.9

42.1

40.5

39.0

37.6

36.3

35.1

38

85.5

78.9

73.3

68.4

64.1

60.4

57.0

54.0

51.3

48.9

46.6

44.6

42.8

41.0

39.5

38.0

36.6

35.4

34.2

37

83.3

76.8

71.4

66.6

62.4

58.8

55.5

52.6

50.0

47.6

45.4

43.4

41.6

40.0

38.4

37.0

35.7

34.5

33.3

36

81.0

74.8

69.4

64.8

60.8

57.2

54.0

51.2

48.6

46.3

44.2

42.3

40.5

38.9

37.4

36.0

34.7

33.5

32.4

35

78.8

72.7

67.5

63.0

59.1

55.6

52.5

49.7

47.3

45.0

43.0

41.1

39.4

37.8

36.3

35.0

33.8

32.6

31.5


To use the gear table, Identify the number of teeth on your chainwheel, and use the numbers in the pink column.
The corresponding row gives you the gear in inches, for the relevant rear sprocket size.


i.e. For every one revolution of the pedals in this gear, you move forward this number of inches along the road!

 

 



Calculator: To work out any gear, multiply the diameter of the wheel (e.g. 26") by the number of teeth on your chainring (e.g. 48), and divide the result by the number of teeth on your rear cog (e.g.13). Now go and wash your hands!