Originally Posted by
Jughed
^^^ interesting stuff C-commute.
I reckon my cassette could be changed, but I would need a longer cage derailleur. I guess one could do that out of the box with a new build...
You said in your post that you have a 34 tooth chainring and a 36 tooth cassette cog. I'm confused as to why you would need to change the derailer or cassette. If you want really low gears like I have you'd have to change a whole lot of other stuff too.
[But the cross chaining aspect. At least with my 2x (105 Shimano), I can run all of the gears in every condition. Big big, small small - no real issues. For the 3x (Shimano Ultegra), the big front and the two big rear are not so good, with the 3rd one being about the same as big/big on the 105. Same for small small. And the middle ring isn't really happy with either the big or small on the cassette. It leaves a lot of gear selection off the table. Makes it more like a 3x7, with some of those options overlapping/having similar ratios between front rings.
I don't need to cross chain because I have lots of other options. You don't really need to run cross chain either. If you are riding in the 34/11 combination, that ratio (84 gear inches) is duplicated in the 50/17 combination. In other words, you should have shifted to the big ring long before. From a strategy standpoint, let's say you are in the 34/11 combination and come over the top of a hill. If you need to shift up, you jump from 84 gear inches straight to the 124 inch gear. Now you are lugging the engine as we used to say back in the days of standard transmissions. You are going to waste a lot of time and energy on finding the proper gear by downshifting. Better to shift down around the 20 tooth range so that you have smaller gradations for shifting up.
The same applies to the big/big combination. Jumping from the 50/36 combination to the 34/36 combination is a large step. You go from a moderate spin to a very fast spin to keep up with the gearing...like from 60 to 120. You have the choice of coasting your bike until it slows enough for comfortable pedaling which results in losing momentum on a climb or you start hunting for slightly higher gears which usually results in losing momentum as well.
I don't ride in big/big nor little/big combinations for this reason. I don't really even ride in the middle/big nor middle/little combination all that much either. If I need a moderate gear, I shift to the middle ring. If I find the middle ring too tall or too short, I shift down or up on the large ring as needed