Just comparing range of gearing between a double and a triple is pointless. For example I run a 24,42,45 triple with a 12-36 (9 sp) cassette. The case could be made I don’t need a triple because if I were to get a 11-36 (10 sp) cassette adding just that one cog the 11t, I would then get the same top gear around 100 GI off the double (24,42), and assuming I like most here feel anything over 100 is useless for touring what good does the big ring do be it 45t or 52t or whatever it is.

For me the benefit of the triple isn’t about the overall range, I can get that fine with just two rings. For me the benefit of the triple is foremost having almost all my gears I need off one center ring that I feel safe in using without cross chaining in any position. Secondly it’s about a really straight chain line in the highest and lowest few gears, mostly the highest as I can really feel the straight chain line when in smallest 3 cogs on my big ring. The last reason I like my triple over a double is if you need the range of a wide spaced cassette like the 11 or 12, 36 you most likely won’t like the bigger jumps between gears. If you plan your triple correctly the big ring will fill in the gaps. The 52,42 that came on the bike did that as a one and a half step gearing and now my 45,42 does it as a half step gearing. If someone came up with a 15 cog cassette it would be equivalent to the spacing I have with my two biggest rings, but who wants to shift 15 times to go from one end to the other. So in that case I feel there is an advantage to half step and actually 9 might be too many cogs if anything. I think I could live nicely with 7 cogs spaced just right and a half step + granny setup. That’s what I had so that’s what I worked with.

The other advantage I hear other people liking a triple for and the one I disregarded in my setup is some people like the center ring as a transition gear because they feel the shift to the granny might be too hard of a jump. Any setups like that I tried I didn’t like because they moved my most used gears between the two large rings. Others don’t mind that at all.

I view my gearing as a double + granny just like the old days where they talked about half step + granny. I’m not concerned about where my shift pattern is transitioning to the granny range I think it’s at least 3 or 4 steps over in the back. For me that’s a whole different bike when in that gear with a gearing between 17 and 45 GI. When I’m on my normal gears (42,45) that range is 31 to 100 GI with 15 evenly spaced gears to pick from.