I originally bought a 2012 Norco Nitro 9.3...
After an emergency repair last year that temporarily turned it into a single speed, I realized that I don't need all those gears. With the 1x trend I figured it was time to make the plunge.
Nothing was wrong with my bike, so I made the decision to do it in place.
What is 1x?
A single chainring in the front, instead of a triple or double - and no front shifter or derailleur. Basically your rear derailleur does all your gear changes.
You can take your existing cassette and mess around with it - add a big bail-out ring, drop some, etc. But if you're like me, you're probably overdue for a new cassette anyway... so I went and bought a new Sunrace MX3 10 Speed Cassette.
This took my rear cassette from 12-36 to 11-42, with reasonable jumps across the whole range.
Here there are a lot of options. The "cheap and cheerful" option is to replace your big ring with a bash guard and dump your small ring... leaving just the middle.
There are all kinds of problems here, though. Without a chain guide in place of the front derailleur, you will probably dump your chain. You can get a different ring that has alternating teeth - but once you buy that and the bashguard, you're talking some good dough already.
I decided my old crankset was probably not worth saving, so I just replaced the whole thing with the Race Face Ride Single Speed Crankset.
I found it online for $99USD, and it included an appropriately sized bashguard! The teeth alternate to keep it firmly where it is meant to be.
Oh and it came with a new bottom bracket! What a deal.
It's 32T - I don't know if it came in any other configurations, but that was perfect for me since it matched my existing middle ring.
Rear Derailleur and Chain Guide
There are people who say you need a special "clutch" mechanism on your rear derailleur.
There are other people who suggest you need a Chain Guide.
These are both to keep the chain from popping off your front ring. So far I haven't had any problems, largely on the strength of the alternating teeth on the front ring. If I start having trouble I'll address it, but I bounced off a lot of stuff without a drop yesterday.
Front Shifter and Front Derailleur
I love it. MTB'ing throws a lot at you, and there are always those times you find the hill steeper than you thought too late and you're in the wrong front ring... no longer. It's just a lot simpler. Less things to go wrong. Probably not massively lighter, but lighter.
One thing I hadn't even thought about is CLEARANCE! I have more of it! I'm on a 29-er so I already had a lot, but there is one log I was putting a lot of chainring marks in... this first ride, cleared it! Yay. And if I didn't, the bashguard is there to take the brunt, rather than bending teeth.
The jumps between gears were not noticeably larger than before. For the road they probably would be - I like to find a pretty specific cadence and stick to it. But MTB it's always pretty dynamic anyway.
Old largest ratio was 3.67:1, new is 2.91:1 - so my top speed should take a hit if I'm ever on roads, which really isn't the priority for this bike. Or my cadence will have to be more hamster-wheel-like.
Old smallest ratio was 0.61:1, new is 0.76:1 - a pretty modest loss of lowest gearing. We went up some steep stuff, and it was fine.
$168USD+tax+shipping. Pretty modest. Being in Canada the exchange rate stings a bit, but still very reasonable.