Question about frame tube diameter

[HellOnWheels]

99 BDM Vintage Sport. Need info regarding frame tube diameter. Dad borrowed (read: f*&$ing lost!?) my calipers at the shop. Looking to fab up a highway bar to mount lights and pegs, need to know what size the frame tubes are so I can purchase clamp mounts for it.

Any help would be greatly appreciated.

 

[woodbutcher]

take a piece of string, wrap it around tube, mark intersecting point with pen, measure that and divide by 3.1417.

 

[Big D Florida]

take a piece of string, wrap it around tube, mark intersecting point with pen, measure that and divide by 3.1417.

Pie are square.
d= C/π

 

[BWG56]

take a piece of string, wrap it around tube, mark intersecting point with pen, measure that and divide by 3.1417.