Originally Posted by
nonhunner
Ah I see. So it doesn't matter on a friction because I just adjust how much I shift. But because the brifter always pulls x distance that needs to translate properly into x distance based on
pulley dimensions so that the lateral shift = 1 cog. Thanks! This is really helpful
In simple terms, it is not really about pulley dimensions, but the pivot action of the parallelogram (the main body) and the attachment point of the cable. The design of those determines the lateral movement of the pulleys.
Something similar effects the front derailleur also. Older FDs used more cable pull and the newer FD used less pull to match cable pull of integrated brake/shifter units. The ratio of the cable attachment arm length relative to the pivot points affects how much the chain-cage moves. See below for the SRAM FD, with very short arm. Older FDs have a longer arm and thus needs more cable pull. This applies to both SRAM & Shimano integrated shift units.
