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Sheldon Brown's Bicycle Crank/Chainring Bolt Circle Diameter Crib Sheet

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Always measure the bolt-circle diameter(s) and order a replacement chainwheel or crank based on the measurement, not a part number. This avoids confusion and also can result in your finding a compatible replacement when an original part is not available.

Also, take note of chainwheel thickness. It is generally possible to use chainwheels made for narrower chain, though shifting may be less good and spacer washers may be needed to avoid interference with the next larger chainwheel. It is often possible to "fudge," using chain for the next higher number of cassette sprockets.

A protruding part may make a direct measurement of the bolt circle diameter impossible even with 4-bolt crank, which has holes directly opposite one another. It is not possible to measure the bolt circle diameter of a 5-bolt crank or chainwheel directly because no hole is directly opposite another, and so the table below gives measurements between adjacent and non-adjacent holes. Measuring between non-adjacent holes increases the difference between measurements, reducing the likelihood of mistakes when bolt circle diameters are nearly the same.

Many references describe these measurements as "center to center," but there is nothing to measure from at the center of a hole! Very fortunately, all of the bolt holes are the same size, and measuring from right side to right side or left side to left side neatly avoids this problem!

5 Bolt Cranks:
BCD (mm) Smallest
Between adjacent holes
Between non-adjacent holes (mm) Application
151 44 88.8 143.6 Very old Campagnolo standard (pre '67) (Obsolete)
144 41 84.6 137.0 Old Campagnolo standard, still used for track applications.
135 39 79.4 128.4 Current Campagnolo standard
130 38 76.4 123.6 Standard Road double and triple (outer 2)
128 38 75.2 121.7 Nervar Sport, Star (Obsolete)
122 38 71.7 116.0 Stronglight 93, 101, 103, 104, 105 (Obsolete)
118 36 69.4 112.2 Ofmega, SR (Obsolete)
116 35 68.2 110.3 Old Campagnolo (Obsolete)
110/112 34 64.7 104.6 Campagnolo CT inner/middle/outer with one bolt at larger diameter behind crank
110 33 64.7 104.6 Touring double, standard triple outer
100 31; 36 58.7 95.1 Merz adapter; Campagnolo triple (obsolete)
94 29 55.4 89.4 Compact triple outer
92 30 53.3 87.5 Shimano Dura-Ace triple inner
90 32 52.9 85.6 Edco, Mavic triple inner (old)
86 28 50.5 81.8 Stronglight 80, 99, 100, some SR triples. (Obsolete)
85 28 50.0 80.8 Old Shimano Deore, Takagi triple inner. (Obsolete)
74 24 43.5 70.4 Standard ("full-sized") triple inner, used with 110 mm, 130 mm or 135 mm rings.
58 20 34.1 55.2 Compact granny
56 20 32.9 53.3 Sun Tour Compact granny (Obsolete)

4 Bolt Cranks:

Beware of Shimano near-matches! Measure!

BCD (mm) Smallest
Between adjacent holes
146 44 103.2 Shimano XTR M960 Hollowtech 4-arm outer
112 34 79.2 Shimano XTR M950, M952 4-arm middle/outer
104 32 73.5 ShimanoXT, LX 4-arm outer, Sugino MX350
102 32 72.1 Shimano 2003 XTR MX960 4-arm middle
68 22 48.1 Shimano XTR M950, M952 4-arm inner
64 22 45.3 Shimano XTR M960, XT, LX 4-arm inner
58 20 41.0 Sugino MX350 4-arm inner

More cribsheets: Click here!

This page is intended as a quick reference primarily for the benefit of folks in the bicycle business. Feel free to print it out, but please don't reproduce it without proper credit and linkage.

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