Chain Length question
I know I can plug the numbers into an on line calculator but I like to know the formulas.
So it appears to me half of the largest front ring tooth count + half of the largest rear sprocket + two times the crank to rear axle length in inchs gives you the min chain length. I assume the angle distance of the chain between front to back doesnt really amount to enough to worry about. How much do you add to that for the bends around the derailleur wheels and to keep the derailer from being pulled up parallel to the chain in the large front and back combination?
One more question, look at Park tools site, Repair and help section under Chain length sizing
In their example they say the chain for a 32 rear , 42 front with 16.375" axle to crank should be 52", I am thinking more like 69. Is it wrong?