2012-06-23 Sat - The Maths Geek Ride 0001.5 - London to Bletchley to London

^^ back in the day, it was a simple calc:
27 (being the nominal wheel size)
x teeth on chainring
/ teeth on sprocket

ie: 27x46/18=69 simples!

Great! (I guessed 67,5... =76/(46/16)x(46/18) but the 76 was just 'around76' soo 77,6)
(Would be funny if I couldn't go to the geek's ride after these 'lots of' calculations... ;S)