Quick question…

Can an x9 rear mech (2015 vintage) take a 40t cog without any rear mech modifications/bodging?

It’s on a camber evo fwiw.

I’m thinking a 1* conversion and a reducer bb for my bb replacement issues here would allow me to use a spare 24mm xt crank, 32T ring and other existing bits to do a bit cheaper. I guess the alternative might be a 30t ring.

PS if anyone knows what the rough chain growth on a camber is that’d be handy to know too.

Thanks as always.

I have a 10 speed X9 mech on a Whyte G-150 with an oval ring and a 42t expander. It all works fine with no special bodging. I may have tweaked the b screw but nothing more. The bike was originally 2 X 10 but I don’t know whether the mechs come in different cage lengths

Cheers for that. Mine is 2*10 so its probably worth chancing a go at it.

If it’s a long cage mech (likely if it came from a 2 x 10) then absolutely – I have a 1 x 10 setup with a SRAM x9 long cage, Sunrace MX3 11-42 10spd cassette. Works great, just wind the b-screw out and off you go.

There are different cage lengths available and I can’t comment if the shorter cages work without bodgery and fiddling.

No problems with my 1×10 X9 set-up (medium cage) running a 40t T-Rex. No major tweaking required.

Thanks all. I’ve got a Sun Race 11-40 coming tomorrow along with new BB and chain.

Then I’ve just got to work out how much chain stay growth to accommodate and put together the 1*10 setup.

Possibly stupid question but is there an easy way to accurately guess how many more links I need from the existing setup to save a lot of guesswork and or shock deflation/measurements?

The only real way to find chain growth is deflating or removing the shock and moving the back end through its arc eyeballing the poin where distance between crank and rear axle appears greatest then tie the back in place with string or similar secured to something like a seatstay bridge or the seat tube and do your normal big-big chainwrap with it like that. Anything else is guesswork. If you have a shock pump it’s not a huge deal, just note the pressure before you deflate it…