Need to bodge for the weekend. There’s a long story, but cutting it short:

Long-cage 9spd XT mech on a 1 x 10 system. Will it work? Or will I die?

Nope

pull ratios are different. you won’t die but shifting will be rubbish

Nope

Work or die?

pull ratios are different.

Know that bit, but figured the pull ratio is actually controlled by the shifter.

you won’t die but shifting will be rubbish

That’s what I was after!

Cable pull at the shifter and leverage at the mech are both different to 10speed

Cable pull at the shifter and leverage at the mech are both different to 10speed

Gotcha – ta.

Found this out the hard way recently.
Shifting actually felt ok, but the different pull ratio meant the mech didn’t sit quite in the right place so ramps on the cassette would cause chain to slip under force. So shifted fine on workstand but an unpredictable nightmare to ride.

My 10sp tourer has Tiagra shifters and a 9sp xt rear mech which is apparently the correct pull ratio. Is that correct for mixing road shifters with mtb mech?