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:|
|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.|
|56||20||32.9||53.3||Sun Tour Compact granny (Obsolete)|
4 Bolt Cranks:
Beware of Shimano near-matches! Measure!
|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|
Last Updated: by Harriet Fell