Hi guy,

I am having a problem with this formula for effective rotor radius
The first says effective rotor radius : rotor dia/2 - caliper piston dia/2
Here is the link below
https://takemebeyondthehorizon.wordp...-5-an-example/
The 2nd says effective rotor radius : D+d
-------
4
Where D = rotor outside dia
Where d = rotor inside dia
Here is the link as well
http://www.engineeringinspiration.co.uk/brakecalcs.html
Which is correct?. Thanks.