That design of Sora lever is exactly the same as the 6800 generation Ultegra, and a 10 speed road mech will work fine with 9 speed shifters/cassette (same pull ratio).
So it’s not terrible, just a bit of a mish mash. The downside for me is you’d still have to spend quite a lot of money to make it 11 speed.
Interesting; my road bike knowledge dwindles significantly past the era of 7 speed. So not wishing to derail the thread too much but that suggests that the correct 10 speed cassette is literally just an extra cog; with the same spacing yes?
No, the sprockets on 10 speed are closer together but the clicks on the shifter are also closer together by proportionally the same amount. Thus it pulls less cable and moves the mech less distance per click.
That design of Sora lever is exactly the same as the 6800 generation Ultegra, and a 10 speed road mech will work fine with 9 speed shifters/cassette (same pull ratio).
So it’s not terrible, just a bit of a mish mash. The downside for me is you’d still have to spend quite a lot of money to make it 11 speed.