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Chainring BCD Guide


Chainring Bolt Circle Diamater Guide


Measuring BCD: This 110 mm BCD ring measures 64.7 mm center-to-center.

Multiplying this dimension by 1.7 will give you the actual BCD for a 5 bolt chainring.

Use 1.4 for 4 bolt chainrings


 Chainrings for 5 Arm Cranks

 BCD
(mm)

  Smallest
Ring

Ctr to Ctr
(mm)

Application

151

44

88.8

Very old Campagnolo standard (pre '67) (Obsolete)

144

41

84.6

Old Campagnolo standard, still used for track applications

135

39

79.5

Current Campagnolo standard. Also Miche track

130

38

76.4 Standard Road double and Road Triple middle, outer

128

38 75.2 Nervar (Obsolete, N/A)

122

38 71.7 Stronglight 93, others. (N/A)

118

36 69.4 Ofmega, SR (Obsolete, N/A)

116

35 68.2 Old Campagnolo (Obsolete, N/A)

110

33 64.7 Touring double, standard triple outer

94

29 55.4 MTB triple outer

86

28 50.5 Stronglight 99, some SR triples. (N/A)

74

24 43.5 Standard "Full-Sized" triple inner. Used with 110, 130 & 135mm

58

20 34.3 Some MTB granny

56

20 32.9 Sun Tour Compact granny (Obsolete)(N/A)

 

Chainrings for 4 Arm Cranks

 BCD
(mm)

  Smallest
Ring

Ctr to Ctr
(mm)

Application

104

32

73.6

Shimano XTR M960, XT, LX 4-arm outer  

64

22

45.3

Shimano XTR M960, XT, LX 4-arm inner