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Shifting troubles 105/GRX (lemmy.dbzer0.com)

submitted 4 weeks ago by hemko@lemmy.dbzer0.com to c/bikewrench@lemmy.world

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So I got some strange shifting issues with my 105 road shifters (ST-R7020) combined with GRX derailleur (RD-RX812). The cassette is deore CS-M5100-11

Now in theory, and according to Shimano's compatibility chart this should be compatible configuration, despite a little mix-and-match

https://productinfo.shimano.com/en/compatibility/C-454

Now the problems I have screams still for compatibility issues with slightly wrong pull ratios

Going from smallest cog to largest, the first 4 cogs are shifting perfectly. Then the next couple clicks want to over shift and skip cogs, and the largest 3 are shifting perfectly again. In total it takes 9 clicks to go through the 11sp cassette. What fucks my mind over, is the top and bottom cogs that shift perfectly, if the pull ratio was wrong, these would have equal problems?

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[–] SimplyGreg@lemmy.world 1 points 3 weeks ago

My first thought on anything like that is always to redo an indexing but also make sure the B screw is set properly, because that can causes so many shifting issues.

The odd part, and what I don't fully understand here, is that it seems to work as a 10 speed? Am I understanding that properly? 9 clicks plus initial position?