trail .. take a line thru the center line thru the fork steerer to the ground.
this is contribution of head angle. and fork length.
then take a plumb line thru the axle center,
this line also to the ground.
trail is the distance on the ground between the points
where the other 2 lines meet the ground plane.
Last edited by fietsbob; 05-16-12 at 07:41 PM.