Schwinn 564 question
 

Hi all
I'm new here & I just wanted to ask if anyone knows any of the crank/sprocket specs on the older 564?
The reason I ask is that I want to replace the factory double sprocket with a triple sprocket for better hill climbing(I live in NW Montana, & boy do we have hills!). I've done a bit of searching on the web & just haven't found much info.
Any info is greatly appreciated!
TIA
robbster