I'm hoping someone here can help identify what crankset I have, and help recommend what I could replace it with (or if I should bother).

First: What I have. The bike is a 1984-ish 23" Norco Monterey that I've had since new. I've converted it to a two-speed, with an SRAM Automatix S2 rear hub running the supplied 18T rear sprocket. The sprocket is running 46mm from the centerline of the 130mm OLD (fwiw, the frame appeared to be about 126mm OLD, but the SRAM comes as 120mm with spacers to make it 130. It's centered with both spacers.


Second: The crankset that's on it. It came with the bike, and has two chainrings. Smaller is either 40T or 42T (forget which right now) and is held on with the hex-headed screws visible in the photos above and below. The larger is probably 50-ish and is riveted to the chainguard. Bottom bracket appears to be 68mm width, and judging from the knurled and grooved rings on the ends i'd guess it's threaded but I haven't taken it apart so I don't know for sure.


Third: Now what?

I'd like to have a single chainring up front, and a chainguard. The existing chainguard would be HUGE even if I ground off the rivets for the second chainring and removed it, so I probably want a smaller one anyway. Unfortunately it's integral to the spokes holding the smaller ring. I *could* just take a Dremel and cut off the outer portion of the guard, but that seems a little too ghetto for me. Also I don't know if it would leave me with anything I could use with other sprockets so it might be pointless.

Can anyone offer any useful suggestions? I'm not sure if a bike this old can even take a modern crankset and bottom bracket, or I might just buy one. I see lots of recommendations for the SRAM S300 crankset, which comes with a new bottom bracket. It looks like a two-ring set too, and I really only want one... I'd like to be able to try a couple of slightly larger rings before finalizing everything too (42 or 44T front), so having a "common" size for things would be best.

Suggestions?