Had enough of the bonkers gearing on my x bike. Its a 10 spd compact drivetrain atm.
I’d like some easy street gearing.
I understand from some research, that for my plan to work with my 105 10spd STI’S, I will need the following, for the sake of argument, a Shimano 10 spd mtb cassette 11-34, and a 9 not 10 speed medium cage mech. Is that right? and a new chain too.

The bits Im not sure about; Dyna-sys, what is that? The replacement chain, should it be mtb specific, and which rear mech?

Any pointers would be gratefully received. 8)