Originally Posted by
Ritterview
I think
gear-calculator is the ultimate way to look at and compare drivetrains. Quite germane to the OP, this is a comparison of Turbotandem's Di2 and my 11-speed triple (actually, I don't have a 28t granny yet, that awaits the on-order
Athena long-cage RD to replace my short cage insufficient chainwrap SR RD).
On top, is Turbotandem's Di2, with the rear cassette about the size of a manhole cover. This provides range that is about the same as the triple. The one-cog jumps aren't
too large, they just have to be called out, lest the stoker dig her aero helmet tail into her back.
On the bottom is the 11-speed triple, with the fine tuning rheostat shifting. We find the cadence that is optimum, and I make many one-cog shifts to keep it
just so. This is quite helpful in
riding with a group of rapidly accelerating half-bikes on rolling terrain.
While Ritterview's chart does show the larger jumps in single shifts I think that it really boils down to his statement that he is able to keep the cadence "just so" with a narrow range cassette. This is the benefit to us of the third ring. While we are able to pedal comfortably between 90- & 100 cadence we put out the most sustained power in the 95-100 range. This means the ability to keep cadence "just so" gets us the last bit of power not available at 92 cadence and still have low gears when needed.
That fine tuning may not be important to you and if it is not then a triple looses some of its appeal. In that case then you can fix your front shifting issues by going to a double. Like I said above gearing is very personal so what works for my team may not be the best for someone else.