I'm try to compare the gear ratio of a IGH (Shimano Alfine 11) with a 10 speed cassette + 3 chainring setup.
I went to Sheldon Brown's gear calculator
I entered all the numbers from my bike and got this result
Here is my interpretation:
The first column group with heading 0.53 (low) shows the gear ratio of the 10x cassette and 3x chainwheel. Example: The number circled green is 34 / 11 = 3.1 Which to me is the gear ratio (correct me if I'm wrong). That first column group tells me the highest gear ratio is 3.8 (e.g. when going downhill), and the lowest gear ratio is 0.7 (not on the screenshot, e.g. when going steep uphill). The IGH has highest ratio 2.15 (not on the screenshot) and lowest ratio 0.53. To me that means on uphills I'll have an easier time with the IGH than with the cassette. However downhills I won't be able to go as fast with the IGH than with the cassette. Is my interpretation correct?
What do the other column groups mean? Consider the column group with heading 0.68 ? Where does the number circled in red come from (because 34 / 11 not equal 4.0) ?
Also where do the numbers 0.53, 0.68, 0.77 etc come from. I know they are from the Shimano specs. Are they really the gear ratios? Aren't the sizes of the single rear sprocket and the front chainwheel (that are installed on the bicycle) required to calculate the gear ratio of the IGH setup?