How to compare an IGH (Shimano Alfine 11) with a 10 speed cassette and 3x chainwheel? I'm try to compare the gear ratio of a IGH (Shimano Alfine 11) with a 10 speed cassette + 3 chainring setup.  

I read Sheldon Brown's gain ratio definition. 

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?
I think you’ve told it to do an Alfine hub with all 3 chainrings and all 10 cassette sprockets, so the computer is obliging. 

Just include one chainring and one sprocket value to get the Alfine table. 

Then calculate another table with all 3chainrings and 10 sprockets but no Alfine 

You’ll get things more like this:



You’ll need to pick your own chainring and sprocket values for the Alfine, point being you can customise these to get the gearing you want. I put in random values (32,17) which give the Alfine something like the range of the 3x10 setup

Edit: a gain ratio of 1.9 may/will feel nothing like a gain ratio of 1.2 when you're climbing, so keep playing around with numbers for the IGH chainwheel and sprocket