I've got Campy Mirage crank arms and I need to determine the proper spindle length for a bottom bracket. From what I know, there is a specific spindle length for every type of crank arm. Anyone know where can I find this info on the net?

Google and ye shall find the answer.

Here's the Sheldon Brown page:
https://www.sheldonbrown.com/chainline.html

I still don't really get it but maybe I just need to read it more attentively.

I read Sheldon's write up and I Googled.....and came up with 111mm. Could I use a 110mm spindle???? I read somewhere that sizing down a mm or so is ok. Thoughts, comments?

is sizing up a mm or so ok as well? i'm running 110 bb's on fc7600's that are pegged to be 109 instead.
hmmm~

Moving to mechanics from SSFG. Some really smart folks over there.

except this is the only subforum we read?

Campy doesn't make a 110mm.

Shimano doesn't make a 109 square taper. The 110mm shimano has the same chainline as the 107mm. So you're off by 1mm on each side. Assuming the proper 7600 bottom bracket (which is no longer available) is symmetrical.