IF there's an article that explains this I'd be more than happy to read it, I'm not looking for a hand holding (although if somebody wants to hold hands sometime.. i do get kinda lonely..)

Err, I need shorter cranks but I like me ratio. How does one measure the spider to make sure new cranks fit current chainring?

Thanks.

i know thats a chainring but the holes should be in the same place, obviously.

edit: then go here to get the bcd.
https://www.sheldonbrown.com/gloss_bo-z.html

or do what dommer says.

you measure the "bolt circle diameter." sheldonbrown.com has info on what bolt-to-bolt distances correlate to what bolt circle diameters.

to finish this off...

Measuring BCD: This 110 mm BCD ring measures 64.7 mm center-to-center.

Multiplying this dimension by 1.7 will give you the actual BCD for a 5 bolt chainring.

Use 1.4 for 4 bolt chainrings

https://www.sheldonbrown.com/gloss_bo-z.html