Mixing tiagra trigger shifters and Xt cassette

[Dave W]

10 speed triggers with a mountain bike cassette - can it be done? Anyone know.
Deraleur would need changing obviously.

[Brucey]

yes; if they are Tiagra 4600 shifters, you will need a 9s shimano MTB mech or a 10s 'road' mech to make it all work correctly. A 10s shimano MTB mech will not work because it uses a different pull ratio.

If they are tiagra 4700 shifters then you need to use a tiagra 4700 10s mech or an 11s road mech. IIRC a 10s MTB mech again won't work, but I'd need to check to be sure of that.

You also need to give a thought to the front mech, if you are having one. That could be at least as big a can of worms.

cheers

[Dave W]

Thanks. I have Tiagra double on my recumbent with ten speed rear giving me a 34- 34 for the hills with 26 inch wheels. If I go to 700c wheels I could do with a 36t rear just to try and keep the low gear. Just weighing up the options - probably won't bother tbh.

[Brucey]

I found some notes on shimano shift ratios and they are as follows;

1.7 = 10s road (including tiagra 4600 series), 9s MTB etc

1.4 = 'road' 11s and tiagra 4700 10s

1.2 = 'dynasys' MTB 10s

1.1 = 'dynasys' MTB 11s

so if you have 4600 series, it is easy; just get a 'shadow' 9s MTB mech.

However if you have 4700 series, finding a mech with a 36T capability that works with your shifters may not be so straightforward.

cheers