Originally Posted by
Retro Grouch
12 = the number of teeth on the smallest cog.
The other number = the number of teeth on the biggest cog. A smaller number, like 24, means the steps between gears will be closer. A bigger number, like 34, means you'll have an easier hill climb gear. Which is better for you is a question that only you can answer.
Brilliant - thanks again.
As this is my only bike it needs to fit all occasions so I'm going to have a look at the 12/13-24/25 8 speeds
Thank you all for your help. I have definitely learned something today