Computing gear ratios
Yesterday, though, I ran over a most wonderful web page by Sariel, a LEGO® aficionado from Poland well-known for his sophisticated TECHNIC inventions. Amongst other things, the page allows to select any combination of TECHNIC gears and displays the resulting gear ratio.
Great stuff and most helpful indeed!
Try it out (and do not forget to browse also the other intriguing pages of Sariel's web page).