Hey, so im thinking about swtiching up my 2×10 drivetrain to go 1×10 by adding a narrow wide chainring and a 40t cassette ring.

Currently i have 24-38 up front and 11-34 up back. i will need to get a new xt cassette so will go 11-36 on that.

Im unsure what size chain ring to get up front…. on my current setup i do use the granny ring to get up some hills but like wise like cranking down the fire roads in a higher gear….. what sort of gearing would a 36 chainring up front give? with an 11-40t cassette? or even a 34 seems the common choice for riders… will that still give a good granny gear when on the 40t cassette ring?

Thanks in advance for your help!

dropping from 11-36/ 24-39 here and guessed at 34/36 for the front with the 40t rear, still going to involve manning up a bit and loosing a chunk of top end. There are some good calcs out there

for example

Your ratio at f24 – r34 is 0.71
With a f30 – r40 you ratio is 0.75

If you want to match ratio you need a 30.
With a 36 that rises to 0.9.

Final drive for f30 – r11 Is 2.73.
A f36 – r11 is 3.27.

My partner is running f30 and r36 (getting 40t at the weekend) and doesn’t run out of gears down bpw.

ECheck your email mate!

Hey sorry for slow reply, hectic month! thahsnk for your info. I was gonna go 34 up front but, im currently running a slx double chainset up front which is 64/104 bcd… I wanted to get a bashring aswell and mount the chain ring on the inner and bashring on the outer but limited to a absolute black 30t chainring as thats all i can find with 64bcd. Still not sure what to do hmmmm!