chainring BCD
How do you determine what BCD a chainring is?

Chainring Bolt Circle Diameter Measurement

It's important to have the correct bolt circle diameter (BCD) when ordering replacement chainrings. Use the diagram and chart below to determine your BCD:



Measure the distance in millimeters between two adjacent chainring mounting holes (center to center). Use this distance (x) to find your BCD in the chart below:

Distance (x) BCD
5 hole chainrings
34.3mm 58mm
43.5mm 74mm
55.4mm 94mm
64.7mm 110mm
71.5mm 122mm
76.4mm 130mm
79.5mm 135mm
84.6mm 144mm
4 hole chainrings
41.0mm 58mm
45.3mm 64mm
48.1mm 68mm
73.6mm 104mm
79.2mm 112mm

http://www.hostelshoppe.com/tech_bolt_circle_diameter.php

That is tops mate :wink:
cheers Dave 8)

sticky for future use please :wink:

got a crank and arm

looks the size of 64.7mm 110mm (or maybe i'm wrong ?)

can any one help !

cheers B :wink:



can these be used on a bmx if i can find the right axle and chain ring ?

They look like deore cranks bendy poss xt/xtr :)

No expert here, but wouldn't a triple crank set up be too far over to the right for a 1 ring bmx set up?

got these in a box of bits - so i didn't spend money on them

so if they don't work it's no worry :wink:

Give it a whirl. Looks like a standard 3 piece bb should fit

110 is the most common, should be safe