In reply to KevinD:
There's a wide price range in the 1x systems. True if you go the dedicated systems like SRAM's XX1 where the cassette alone is £200 then they are expensive, very expensive for what in the case of the cassette is a consumable. I think the full system is over a grand at shop prices.
However it's perfectly possible to get a 1x10 system for the same price as the more normal 3x ones. The usual method is to take a 10 speed XT cassette, remove the 17T cog and put an extender cog on the end - I've a Hope 40 TRex which costs £47. Against that you don't need a front derailleur or shifter which saves around £50. The Narrow-wide single ring chainset is close enough to the same price as the 3 ring one to call it even. You don't need a special rear mech so that's even cost as well.
I've run a 1x10 setup on my hardtail for 15 months, I doubt I'd go back. I've replaced the entire drivetrain once but I have done 3500Km of riding on it. I changed the chain at 1500Km and the full system (though not the extender) at about 3000Km. You do get heavier wear on the chainring as all the wear is on one rather than spread between three. I don't use the extender much (it's aluminium rather than steel) so I reckon it will last another cassette after this one which would make its effective cost £16 per cassette.
YMMV of course
I reckon I lose about 1.5 ratios at top and bottom compared to a 3x10 drivetrain but it depends on what size chainring I fit. I just like the simplicity of it - starting to spin out then go up a gear, starting to grind then drop a gear. There's no wondering whether to shift the front then compensate for the huge difference by moving through the cassette. Also not having a front shifter makes room for the dropper post remote!
