[CurbDestroyer]

Using a standard steel 68mm Bottom bracket, 1-1/8" seat tube @ 72.5. Where you do position the front derailleur braze-on on a road frame that will max a 54-t chainring?

 

[customfab]

according to Shimano spec 146 mm will cover anything between a 50 and 55 tooth ring, that number is to the center of the braze on.

 

[CurbDestroyer]

according to Shimano spec 146 mm will cover anything between a 50 and 55 tooth ring, that number is to the center of the braze on.

From the Center of BB I assume.

 

[customfab]

Yes

I've never seen a dimension that indicates off of the shell of the BB