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

revised and updated by John Allen
Drawings in Autocad by Jacob Allen

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Most bicycle chainrings have between three and six bolt holes to attach them to the crank, spaced around a bolt circle. The tables at the bottom of this page give bolt-circle diameters for major brands. Aftermarket and less prominent brands tend to use the same bolt-circle patterns as the major brands. Since approximately 2010, there has been a rash of new bolt-hole patterns with uneven spacings. Compatibility may depend on more than only the bolt-hole pattern. Details about other factors affecting compatibility are on a separate page. Template example

Templates

Our PDF templates linked from this page -- example at right -- cover BCDs for all chainrings in commercial production, old and new, of which we know. You identify the bolt pattern simply by laying a chainring down on a template printout and rotating the chainring until the bolt holes align. Then come back to this page to find out which common brands and models use the bolt pattern that you have identified.

Measurement using a ruler

The table below on this page gives the dimensions that you need to measure using a ruler. Instructions have been moved to a separate page.

Table of bolt-circle diameters

4-Bolt Cranks/Chainwheels, even spacing:

For uneven spacings, see the next section of this table.
Beware of near-matches! Measure!
The BCD is 1.414, 1/sin 45°, times the spacing between adjacent holes.
BCD (mm) Smallest
Ring
Between adjacent holes
(mm)
Application
146 44 103.2 Shimano XTR M960 Hollowtech 4-arm outer.
120 36 84.9 SRAM 2 x 10 and XX. Threaded.
112 34 79.2 Shimano XTR M950, M952 4-arm middle/outer
110 34 77.8 FSA K-Force Light, Vero Pro
104 30 73.5 Shimano XT, LX 4-arm outer 12 SPD, Sugino MX350. Some are threaded. See RaceFace compatibility table.
102 32 72.1 Shimano 2003 XTR MX960 4-arm middle,
96 30 67.9 Shimano compact triple cranksets models M782, M672, M622, M612
94 30 66.5 SRAM XO1, X1, GX, NX
90 30 63.6 FSA: K-Force Modular Supercompact, Omega Pro, Powerbox Supercompact Stealth, Road Modular, Vero Pro
88 28 62.2 Shimano M985
68 22 48.1 Shimano XTR M950, M952 4-arm inner, FSA Comet Modular
64 22 45.3 Shimano XTR M960, XT, LX 4-arm inner. See RaceFace compatibility table.
58 20 41.0 Sugino MX350 4-arm inner

4-Bolt Cranks/Chainwheels, uneven spacing:

Measurements between adjacent holes of uneven patterns
are adjusted to nearest whole degree of angle between bolt holes,
reflecting probable correct values.
The first number given is for holes either side of the crank.
If there are three spacings, the last and smallest is for holes opposite the crank.

BCD (mm) Smallest
Ring
Between adjacent holes
(mm)
Application
145 44 111.1, 93.2 Campagnolo Super Record, Record, Chorus 2015- outer
112 34 85.8, 72.0 Campagnolo Super Record, Record, Chorus 2015- inner
110 34 90.1, 63.1 Shimano Dura Ace 9000, Ultegra 6800, 105 5800, Tiagra 4703, 4700; Dura Ace with modification
110 34 89.0, 64.7 SRAM Apex 1. 72/108 degree angles. Shimano is 70, 110 degrees.
110 34 84.3, 77.8, 70.7 FSA Gossamer ABS, K-Force ABS, Powerbox, SL-K ABS
100 32 92.7, 64.3, 58.8 3T Torno. Must use 3T bolts. Looks like a 5-bolt pattern with one bolt missing.
96 30 78.6, 55.1 Shimano XT M8000, SLX M7000, Deore M6000, 10mm holes; XTR M9000 and M9020, M7 threaded holes.
96 36 73.5, 67.9, 61.7 FSA 96/68 SLK MTB ABS
76 26 65.8, 48.9 FSA Afterburner, Comet, K-Korce, SLK MTB ABS
76 25 62.3, 53.7, 48.9 SRAM XX1 11-speed, Cannondale, Specialized Stout. Threaded for M8 bolts.
68 22 52.1, 48.1, 43.7 FSA Comet MTB Modular, Comet triple, K-Force Modular, SL-K MTB Modular, V-Drive MTB Modular
64 22 52.4, 36.7 Shimano XT, SLX, XTR 11-speed with the "X" shaped bolt pattern.

5-Bolt Cranks/Chainwheels:
The BCD is:
1.701, 1/sin 36°, times the spacing between adjacent holes,
1.052 , 1/sin 72°, times the spacing between non-adjacent holes.

BCD (mm) Smallest
Ring
Between adjacent holes
(mm)
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; Sturmey-Archer FCT
135 39 79.4 128.4 Current Campagnolo standard
130 38 76.4 123.6 Standard Road double and triple (outer 2); Sturmey-Archer FCS
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 Gran Sport touring, Victory, Triomphe
110, 112 34 64.7, 65.2 104.6, 105.6 Campagnolo CT inner/middle/outer with one bolt at larger diameter behind crank
110 38 77.8, 70.7, 46.5 FSA K-Force ABS: uneven pattern, 4 bolt with extra bolt behind crank
110 33 64.7 104.6 Touring double, standard triple outer
102 32 60.0 97.0 Avocet triple inner (obsolete). Note, NOT same as Campagnolo.
100 31; 36 58.8 95.1 Merz adapter; Campagnolo triple inner (Obsolete)
94 29 55.3 89.4 Compact triple outer
93 28 58.5, 52.7, 55.3,
54.0, 52.7
Wolf Tooth "CAMO", barely noticeable uneven spacing, requires Wolf Tooth spider and bolts.
92 30 54.1 87.5 Shimano Dura-Ace triple inner
90 30 52.9 85.6 Edco, Mavic triple inner (old)
86 28 50.5 81.8 Stronglight 80, 99, 100, SR Apex (Obsolete). Chainwheels must be installed back to back, triple shifts poorly.
85 28 50.0 80.8 Old Shimano Deore, Takagi triple inner. (Obsolete)
80 26 47.0 76.1 Tevano (TA Campagnolo clone) triple inner. Bolts not interchangeable with others.
74 24 43.5 70.4 Standard ("full-sized") triple inner, used with 110 mm, 130 mm or 135 mm outer.
58 20 34.1 55.2 Compact granny
56 20 32.9 53.3 Sun Tour Compact granny (Obsolete)
50.4 n/a 29.6 47.9 TA Cyclotouriste, Criterium, Lambert, Shimano Deore, others: attachment for outer chainring; 7 mm holes.
6- and 3-Bolt Cranks/Chainwheels:
The BCD is:
2.000, 1/sin 30°, times the spacing between adjacent holes (6-bolt),
1.154 , 1/sin 60°, times the spacing between adjacent holes (3-bolt)
or non-adjacent holes (6 bolt)
BCD (mm) Smallest
Ring
Between holes
60° apart (mm), 6-bolt
Between holes
120° apart (mm)
Application
157   78.5 136.0 Several very old Euro models
152 43 76 131.6 TA Criterium bolts between outer chainwheel and others.
143 42 71.5 123.8 Lambert. Inner ring threaded.
140 40   121.2 Campagnolo Gran Sport inner
116 36   100.4 TA Professional (10 mm holes), many old Euro steel cranks
116 36 58 100.4 TA Randonneur: bolts are between outer chainwheel and others.
112 ?   97.0 Takagi
106 32   91.8 Sugino Maxy, others w/8mm holes, SR Apex w/10mm holes.
95 30   82.3 Shimano 600, 310
88.9 (3.5") 30?   77.0 Nicklin, Cross, Williams (very old)
86 28   74.5 FSA Pro MTB 386, Comet 386 MTB
85 28   73.6 SR Custom 3
80 26 40 69.2 TA Cyclotouriste, Lambert: bolts between outer chainwheel and others.
70 24   60.6 René Herse. 10mm holes.

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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