I’ve just upgraded to 1×10 as I started a new build. My old 3×9 XT is in decent condition but realistically is there a market for it? Not sure it’ll be worth the cost of posting and hassle involved for its actual value. Should I just keep it and use it to upgrade my daughters first full sized bike?

There might not but much of a market for the gear whores on here (me including having just gone 1×11) but have you looked at eBay? Bet there’s plenty of folk on there who’d like to upgrade to XT.

How decent is decent? Shifters and mechs maybe it why not just reuse it yourself.

There’s definitely still a market for 3×9. Have a look on eBay and see what the going rate is, then put an advert in the classifieds on here.

Cranks will still be usable still, keep them for spares or flog them, just don’t expect a fortune.

It might be worth hanging on to mechs for kids bikes, my daughter’s bike got an “upgrade” from 1×6 to 1×9 thanks to the spares bin, and spare drivetrain parts are generally always worth having IME…

Would make a decent 3x or 1x chainset whether 9 or 10 speed.

You’ll have no problem selling it.

still on 3 x 8 here…. I refuse

I won’t be “upgrading” to 1x anytime soon, would have stuck to 8 speed like walla24 if I’d had any sense, 9 speed is still an upgrade to the majority of bikes out there & if its decent level XT or above it will sell but probably more likely to sell on ebay than on here.