Straightforward method to measure distance of cranks from seat post

[blimpnoddle]

I am replacing a square taper bottom bracket with a Hollowtech II and also fitting a different chainset. I would like to know of a straightforward way of measuring the distance from each crank to the seat post so I know everything is centred properly.

 

[I like Skol]

Just measure from the back of the crankarm where the pedal screws in, to seat post. If this is the same distance then the cranks are centred. This does not mean the chainline is correct though.

EDIT: A ruler or tape measure should be adequate.

 

[Levo-Lon]

Chain line, you can align the chain with the centre of the cassette so its inline.
Also you can measure chainring to frame before removing old one and work with that assuming its correct.

Have a read here
https://www.sheldonbrown.com/chainline.html

 

[raleighnut]

You can't adjust HT 11 unless you fit a 73mm BB in a 68mm shell.