alot of people have been asking this so i thought id put this up
p.s if you like your gearing more powerful the smaller cog on the back would be best and vice versa)
front 22t use 17t,18t or 19t
front 20t use 15t or 16t
front 18t use 13t or 14t
front 16t use 12t or 13t
it may be best to try them all to see which best suits you