Quote:
Originally Posted by Xrslug
Because I love tinkering with my bikes, I’ve been kicking around the idea of converting my hardtail into a drop bar configuration. Currently running XT 12-speed.
I’ve read in various places that the new GRX 12-speed STI lever is not compatible with Shimano 12-speed MTB derailleurs, supposedly because of “different pull ratio.”
Given that the the new GRX lever unit shifts the GRX long-cage 12-speed derailleur, which is expressly compatible with Shimano 12-speed MTB cassettes, how can the GRX lever unit not be compatible with a Shimano 12-speed MTB derailleur? It’s shifting on the same cassette, both in cog spacing and cog size, but somehow the “pull ratio” is different and incompatible?
I like to understand how things work (and would prefer not to replace my XT derailleur), so curious for the explanation here.
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The cable pull ratio is different, thus the indexed GRX shifter won't put the derailleur in the right place, as the amount the cable is pulled when you push the trigger differs between these two systems. You need to replace your XT derailleur, or look into weird solutions like a travel agent (if such a thing even exists for this particular ratio change).
Or you could use a friction shifter, but I wouldn't recommend it on 12 speed.
Or or... you could use an indexed bar-end shifter. Microshift makes a 12-speed Shimano MTB compatible barcon (
https://www.microshift.com/models/bs-m12-r/)