carpediemracing said:I use gear inches to compare gears - chainring/cog x 27". It's simple and easy to relate to the different gears. If you do the math, you'll see a one tooth cog difference in the 11-12T range is worth about 10%. A one tooth chainring difference is something like 1%.
Why 27"? Using circumference gives someone an easily understandable number, i.e. how far the bike rolls with one turn of the cranks.