From a post by Will at Rivendell Bicycle Works – 28 May 2021
|One of the main advantages of friction shifters used to be that they work with basically any set up – any derailleur, any crank and any cassette, allowing riders to ignore almost all of the overly complicated compatibility rules that goes along with indexing. |
At least, that was the case until Shimano started designing derailleurs, both front and rear, that only work with brifters or trigger shifters.
They haven’t done it across the board and friction shifters still kinda work with the derailleurs in question but don’t feel nearly as good as they usually do and make it really hard to find and keep the gear you want.
|Shimano changed their design so the tall arm and the angle at which the cable approaches the pinch bolt (pinch plate in this case) changes the amount of leverage needed at the shifter to move the derailleur over. |
This pull actuation works with indexing brifters and triggers but it’s terrible with friction shifters.
The older style of cable pull worked perfectly and was backwards compatible with whatever old Suntour downtube shifters were in your parts bin.
|These look better than the XTR linked above, but the arm profile is still no good for friction shifting. |
Rivendell call this style of friction-unfriendly cable pull SneakyPull.
The new Tiagra rear derailleur has a similar new pull actuation that the Claris and Sora fronts have.
|You can see how the cable has to take a sharp turn as soon as it leaves the housing arm, and how far away the pinch bolt is:|
|Looking at them both you can see how the top one would require more effort at the shifter to pull the spring out of it’s slackest position which is what makes friction shifters feel gross.|