The table below gives bolt-circle diameters for major brands. Aftermarket and less prominent brands tend to use the same bolt-circle diameters, for compatiblity.
With an even number of holes, a protruding part may make a direct measurement of the bolt-circle diameter possible only with a caliper, not a ruler. No two of an.odd number of holes are directly opposite another, so the table gives mesaurements betwen holes. Measuring between non-adjacent holes increases precision, reducing the likelihood of mistakes.
Many references describe BCD measurements as "center to center," but there is nothing to measure at the center of a hole! D'oh! 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 of holes avoids this problem!
Most 4-bolt and 5-bolt chainwheels have 10mm bolt holes, though some have 8mm or are threaded.. Most 3 and 6-bolt chainwheels have 7-9mm bolt holes. Other variations which affect compatibility::
Having the same BCD and hole spacing does not necessarily make chainwheels compatible. They may have different-sized bolt holes, threaded or unthreaded, and different tooth alignments, pins and ramps to shift smoothly with specific other chainwheels. After measuring BCD, you might check Wolf Tooth's Road and MTB chainwheel entries for details on newer 4- and 5-bolt chainwheels; also Race Face's compaitbility guide. . Wolf tooth also offers a guide to direct-mount (spiderless) chainrings at the bottom of this page.
Bolt-hole spacings from the previous version of this page were based on measurement, which is never exact. They have been slightly adjusted to reflect exact (known) angles for evenly-spaced holes, and an integer number of degrees for unevenly-spaced holes. All the Shimano measurements for unevenly-spaced holes translated so nearly to 70 and 110 degrees that this is probably correct; SRAM had to be different, and its spacing appears to be 72 (same as with a 5-bolt chainwheel) and 108 degrees. Wolf Creek CAMO is an entirely different and more complicated story. If you can provide corrections, please do! A Microsoft Excel workbook with calculations of all the dimensions used on this page is available on this site.
Many thanks to Ulrik Dobashi Hansen for updates to the 4-bolt crank list.
are adjusted to nearest whole degree of angle between bolt holes.
Beware of near-matches! Measure!
The BCD for evenly spaced patterns is:
1.414, 1/sin 45°, times the spacing between adjacent holes.
|Between adjacent holes
|146||44||103.2||Shimano XTR M960 Hollowtech 4-arm outer.|
|145||44||102.5||Campagnolo Super Record, Record, Chorus|
|120||36||84.9||SRAM 2 x 10 and XX. Threaded.|
|112||34||79.2||Shimano XTR M950, M952 4-arm middle/outer, Campagnolo inner.|
|110 uneven||34||63.1, 90.1||Shimano Dura Ace 9000, Ultegra 6800, 105 5800, Tiagra 4703, 4700; Dura Ace with modification|
|110 uneven||34||64.7, 89.0||SRAM Apex 1. 72/108 degree angles. Shimano is 70,110.|
|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,|
|100 uneven||32||58.8, 95.1||3T Torno. Must use 3T bolts. Measurements are approximate. Apparently 4 sides of an equilateral pentagon.|
|96||30||67.9||Shimano compact triple cranksets models M782, M672, M622, M612|
|96 uneven||30||55.1, 78.6||Shimano XT M8000, SLX M7000, Deore M6000, 10mm holes|
|96 uneven||30||55.1, 78.6||Shimano XTR M9000 and M9020, M7 threaded holes.|
|94||30||66.5||SRAM XO1, X1, GX, NX|
|76 uneven||25||49.0, 62.3, 53.7||SRAM XX1 11-speed, Cannondale, Specialized Stout - symmetrical only around axis of crank. Threaded for M8 bolts.|
|68||22||48.1||Shimano XTR M950, M952 4-arm inner|
|64||22||45.3||Shimano XTR M960, XT, LX 4-arm inner. See RaceFace compatibility table.|
|64 uneven||22||36.7, 52.4||Shimano XT, SLX, XTR 11-speed with the "X" shape bolt pattern.|
|58||20||41.0||Sugino MX350 4-arm inner|
|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; S-A FCT|
|135||39||79.4||128.4||Current Campagnolo standard|
|130||38||76.4||123.6||Standard Road double and triple (outer 2); S-A 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||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,
|Wolf Tooth "CAMO", Uneven spacing, requires Wolf Tooth spider and bolts.
Dimensions are reverse-engineered from photos, may be slightly wrong.
|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.|
|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)
60° apart (mm), 6-bolt
120° apart (mm)
|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 Grand Sport inner|
|116||36||100.4||TA Professional (10 mm holes), many old Euro steel cranks|
|116||36||58||100.4||TA Randonneur: bolts is between outer chainwheel and others.|
|106||32||91.8||Sugino Maxy, others w/8mm holes, SR Apex w/10mm holes.|
|95||30||82.3||Shimano 600, 310|
|88.9||77.0||Nicklin, Cross, Williams|
|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.|
Last Updated: by John Allen