BCD question

[Kins]

Got a Tracer Crankset and wanting to get smaller chainrings. Measuring the BCD seems to be 70mm center to center.

This makes 140mm BCD.

Please tell me I am an idiot and measuring wrong?

 

[jon w]

Not quite.

You need to measure from the crank center line to the bolt center and get the Pitch Circle Diameter (PCD) by multiplying the measurement by two. You can then specify the PCD and the number of fixing bolts (looks like 5 in your case).

I useful 5 hole table is below

http://www.sjscycles.co.uk/bolt-circle- ... lbcdchart/

 

[Kins]

Not quite.

You need to measure from the crank center line to the bolt center and get the Pitch Circle Diameter (PCD) by multiplying the measurement by two. You can then specify the PCD and the number of fixing bolts (looks like 5 in your case).

I useful 5 hole table is below

http://www.sjscycles.co.uk/bolt-circle- ... lbcdchart/

Arh, that makes more sense than the table I was using. Looks like its 110 BCD.

Cheers.