Gearing chart?
 

Where can I find one?

I want to see matching gear ratios for different chainring sizes. (crank length being the same)

Thanks

There is one on sheldon brown's site if you google for "bicycle gear calculator" it is one of the first results. Also, if you are just trying to find equivalent ratios you can divide chainring/cog such as 53/12 = 4.417 and 50/11 = 4.545

50x25 is the same as 42x21.

http://www.panix.com/~jbarrm/cycal/cycal.30f.html
http://sheldonbrown.com/gears/

thanks :)