Not sure if this is the right forum for this, if not can someone point...

What would it take to convert a 24sp MTB into a 1 x 8 -- drop the left shifter, front derailler, extra rings, etc. I have a rigid MTB with street slicks for urban riding. Sure I could just leave the left shifter alone, but where is the fun in that? Plus its winter, so why not build something.

Currently the bike has a 22/32/44 Ritchey Comp crank (square tapper). 32/12 might be a bit on the low side though so I may need a new ring (or a new crank?). It looks like I could run up to a 44t (maybe 46t) on the middle w/o getting too close to the stay (not sure there are 44t ring guards).

Would I need an inside guide just for street riding?
Can you run a road crank on a MTB with the right BB?
Are ramped rings ok to use?

Thanks for all your help.

Drop the front der/shifter and chainrings. Shorten your chain accordingly. Ramped rings are fine unless you start dropping the chain. Several solutions to chain dropping. Give it a whirl. This is one upgrade that is free. Of course you may need shorter chain ring bolts.

I dropped the shifter and cable and left the derailler as a guide to stop inside drops, outside I can put back on with my hand. Next take off the rear stuff and you're there. Viola SS.

Assuming you're running 26x1.5 tires, 32x12 comes out to just under 67 inches. This would have you coasting on most downhills, but would have you cruising comfortably on the flats. The only real problem is that the smaller cogs do not last as long. You might consider getting a larger chainring. On my 'crosser (1x9), I've run without a chain watcher or guard once before, and this was fine for asphalt use. If you're gonna hit the trails, you should consider a chain watcher and bashring/guard. And, as others have said, be sure to take the slack out of the chain. This will increase chain tension, which will help keep the chain on the ring.

Cranksets know nothing about what kind of bike they are installed on. A road crank would work just fine when installed onto a bottom bracket with the correct shell and spindle size. Sheldon Brown has said a few words on chainline (http://www.sheldonbrown.com/chainline.html) (in this case, you'd want something close to the position of your middle ring).