Spanky_Ham
Porcinus Slappius
You're too young to remember the 210 year old method that involved tying string around ones dangly bits and getting them as close to the chain/gear combo to see if there were any alignment issues....then, Nicole Kidman invented the BMX...... and many young people rejoiced, and slid down water slides.....Speaking of...if teenagers have been getting chain line right in their garages on bmx for the last 209 years it can't be that difficult.
S