I am currently running 2x 9 ( but on a 3x chain ring)
What do in need to go to 1×11

I am guessing:-

New rear cluster
New rear mech
New rear shifter on bars
New chain ring / cranks
New chain

Is that it?
Ta!

Sounds about right, but you need to check that an 11 sp cassette fits on your current 9 speed freehub. Think it does for shimano, but someone here will know for sure.
You could keep the cranks probably, with the new narrow wide chainring on the middle, although it might not look the best.

Get a new gear cable and outers to replace your 8 year old ones 🙂

You may not need cranks if you can just fit a narrow wide chainring to where your original middle chainring was.

Shimano 11 speed cassette will fit straight on from a 9 speed one.

Be prepared for the worst chainline you’ve ever witnessed though! 😯

I was ok with my old 3×9 chainset with one of the narrow wide rings with built in spacers. Shimano ok on standard 9 speed freehub

Spend your money on an upgrade instead like new brakes or tyres or whatever.

Costs outweigh the benefits. IMO.

New rear cluster
New rear mech
New rear shifter on bars
New chain ring
New chain

Spend your money on an upgrade instead like new brakes or tyres or whatever.

Costs outweigh the benefits. IMO.
which is probably where I have been for the last 5 years ….
I guess if I buy a new bike it is worth it but 2×9 has worked well so far …
But I wanted to assess the cost
Thanks

The cost is usually off-set by changing when your existing drivetrain is finished.
Swapping out a perfectly good 2×9 would be extravagant, but most people don’t do that.

two ways to approach it:

if you really fancy doing an overhaul and going 1×11 and your 9 speed kit has life left and has value then sell it before it’s fit for the bin to help offset the cost.

Or

if your 9 speed kit is shot then do it anyway.

To keep cost down I would go SLX RD and possibly shifter (don’t actually like my XT 11 speed much). Cassette wise I would either go Sunrace MX8 or XT. You could go sram if you can get an XD driver for your hub but that is extra cost both for the driver and cassette. Also if you have 104 bcd then going for a 46T cassette means you have better front ring options as you can only go down to 30T round and 32T oval on 104 bcd.

I would go 32 or 34T oval ring, I run 34T oval on my 26″ hardtail with an 11-42T cassette (46T wasnt out).

Ring wise try oval.