I have a hybrid bike that I want to change the drivetrain from 3x9 to 1x10 and I don't know what crankset would fit my bike.

The current crankset on the bike is Shimano Acera FC-M391 with BB-UN26 square taper bottom bracket.

Can I fit threaded bottom bracket to the bike or do I still need the old style square taper bottom bracket?

If you have a square taper bb, you have a threaded bottom bracket shell.

While your current crank isn't the sexiest thing around, you can also just install a narrow wide ring on it and not get a new crank.

A threaded bottom bracket (I assume English threads) will take numerous bottom bracket designs including cup-and-cone, cartridge and external bearing types so you choice of crank models is very wide. The crank can require square taper, splined (Octalink or ISIS) or have a built in spindle like Shimano Hollowtech II or similar.

As to fitting a different chainring to your current crank, I'm not sure but I think the Acera has riveted chainrings and they aren't changeable so you will require a new crank.

This document shows chainring bolts being used on that crankset: https://zzk.lv/files/pdf/107
This one shows the chainring BCDs as 64/104: https://cycle.shimano.co.kr/media/tec...9830745522.pdf


So it should be possible to change rings.

OK, I guess Acera is far enough up the Shimano foodchain that the chainrings are bolted on, not riveted. That gives the OP the option of fitting a single chainring. He will need shorter bolts.

Basically, you have to pile up money, shifter, cassette hub may not take a 10 cog cassette, so new wheel, re cabling..

then maybe you lust for a special new crankset...

9 by 1 is simpler you just remove the outer chainrings get a different one for the middle with full height teeth.





....

This + why?

Have you done the calculations as to what gears you will loose?

Even going 1 x 9 you will probably need to look for a wider range cassette, and these are not too common, Sunrace do a 11-40, but your have more jumps than a 10 speed.

I'm a big 1x fan, but have to ask what your goal is? Is anything broken and needs replacement anyway?
did you calculate if the range is still what you need?

I once converted a 3x9 to a 1x9, but that was more based on the FD failing - it converted itself. I ended up installing new BB and single chainring crank, but that was kind of not needed, could have just kept the old crank and left chain on middle chainring.

If you go up, try to go to 1x11 to make it worthwhile and get more range.

BTW, 10-speed cassette should work on your hub if it is 9x now. 11-speed may or may not work.

I could see it for a commuter or a grocery getter in terrain where you don't need that much range. I mean why not? Bike tinkering doesn't have to make sense.

You might want to read this thread:

Home-made 'sub compact' 42/30

8-9-10 cassettes are all the same width, as far as Shimano compatible cassettes go, Bob. Wheel will be fine as-is.

cabling will be reduced, only the right shift cable will require a new cable if not reuseable. If not rusted, frayed, bent, or crushed too much by the pinch screw, it may be fine.
If not new/recent, i'd slip a new one in as maintenance, personally.

CHAIN should be replaced to match the new cassette's/chain ring's freshness.

I want to simplify that bike as I mostly use it as a commuter/town bike and I don't need a wide range of gears as I don't ride lot of steep long hills. If I need more gears I just use one of my other bikes.

My crankset/chainrings have a slight wobble in them and the fd is tired and that's the also why I want to change the drivetrain.

The rear hub is a shimano deore and I know that it takes up to a 10 speed cassette.

I know it's going to cost money but I think it's going to be worth it in the long run as I would probably need to replace all those parts on the bike anyway in near future.

perfectly legit reasons. Not that you need our approval....
You could consider getting a new BB, like an external cup one with sealed bearings. When I did the similar conversion I bought a shimano hollowtech 1x crank and it came with a new BB for "free". You'll save some weight, more rigidity and if your bike is worn as you say, the old BB may need replacement anyway.

When I changed from 3x9 to 1x9 I felt liberated, even with less range.

I have a 3x9 bike and the front derailleur stopped working. I got the chain onto the middle front and kept it there. To my surprise, i didn't need the other two front gears. So if you want simplicity, just keep it in the middle front wing.

pffff it will even take an 11 speed mountain bike cassette and if you really wanted to get crazy Sunrace now makes a 12 speed mountain bike cassette that uses the standard freehub. It is the ROAD cassettes that become a problem.