Converting road bike to 1x9?
 

Buddy of mine gave me his old Felt for parts because the frame was cracked. I have a 92 C'dale R900 frameset I was wanting to build into an upright cruiser/townie. Felt had 105rd on it with a Hyperglide 9 spd. Would it be possible to run a 1x9 setup with this?

Yes

Check out the 9spd Advent group from microshift. Stuff is cheap and works well. Key is a rear derailleur with a clutch and a narrow/wide chainring. The even have a 11/42 cassette. Retail on everything but the chainring is $125. A little cheaper if you already have a cassette

Ok, so narrow-wide is required?

You will probably want it... You might not need the clutch der in the event you have a narrow wide chainring. I have been using a 1x10 with a wolftooth with 0 dropped chains.

At least go narrow wide, clutch would be bonus territory. Required on dirt, an option for pavement only. Hence, the microshift system.

Well, I have a Shimano 600 crankset I was gonna use. Did some googling and the MTB forums just say run a SS chainring and it should be good. I can get a 39t FSA SS ring in 130bcd 3/32 for like $18

I rode my Poprad for several years with an XT 9 speed RD, 38T Ultegra front ring with a bash guard and Jump Stop and the chain never came off. It was cheap and it worked great for me. YMMV

I run a bike 1x9 with a front derrailleur not hooked to the shifter, and a chain catcher.
Never drop the chain. Normal chainrings; no clutch.

For a commuter just use the existing parts plus a chain keeper like a Paul. Should be gtg.

I run 105 5800 in a 1X setup on my Ultimate with no FD or chaincatcher or clutch. Key is the Wolftooth chainring which fixates the chain. No drops.

Sure, easy..get some short CR bolts, take the front shifter off..go ride. Since it's a 'townie' and not real bumpy, no need for a narrow-wide CR, altho one would be fine. If it is bumpy, leave the front der on as a chain watcher.

If you want to lose the front derailleur put on a chain keeper. if you want to spend no money on it use a front derailleur screwed into place with the cable fixed in from the BB cable guide. No need to spend cash on new chain rings, just take a few links out of you chain. Of course this assumes you aren't going too much off road.

If the Felt had a double or triple set up why not just transfer the whole drive train?

I'm doing the same thing to a 93 R600. Since it's just a townie I run a 44t front and a 11-28 in the rear with a 6500 ultegra and tiagra trigger shifter. An narrow wide ring is nice to have but I just run an outer bash guard and the ring on the inner position. Sounds like you have what you'll need but I like swept back bars for townies which need a 22.2 clamp trigger shifter.

You're going to want at least one of:
-narrow/wide ring,
-clutch rear derailleur, or
-chain keeper/front derailleur

If you're already buying a new chainring, just get a narrow/wide ring.