How To Measure Chainring Bcd . Notes for those the plan to run a 32t chainring on a. This is the easiest method to use for chainrings with five bolts.
The outside chainring bcd is stated on crank as 120, the inner is not given. On bicycle chainrings, this dimension is usually measured in millimeters. Bcd = colt circle diameter, the 4 or 5 bolts are arranged in a circle, the diameter of which is the bcd.
The bolt circle diameter (bcd) is the diameter of the circle that passes through the centre of the bolts on your chainring.
How to measure bolt circle diameter (bcd) bolt circle diameter (bcd) is the diameter of the circle that goes through the center of all of the bolts on your chainring. For the xx1 spider, we recommend the 6mm bolts (or any short m8 chainring bolt). I am looking to put a narrow wide ring on, i think the outer ring is too big to fit a 32 tooth nw ring. With this measurement (b) you can refer to the table below to identify the corresponding bcd, or use one of the following equations: