General Cycling Discussion - cranks on department store bikes?

My friend recently bought me a cheap 70's department store bike (10-speed) but it's not in my possession yet. I'm hoping to convert it to a fixed gear. I was wondering if anyone knows what type of crank these bikes typically have. But my real question is: will I be able to remove extra chainrings and just use the largest one? (I'm trying to avoid buying a new crank)

Thanks!

Probably a one piece crank with the chainrings rivited together. I only have one bike with that type of crank and the chainrings are replacable. They can be bought from anyplace that stocks BMX parts.

Yep - and they are called by the name of the place where they were first manufactured in quantity: Ashtabula (Ohio) cranks.

Cool! So it's probably best that I buy a new crankset? I don't know what kind of BB the bike has yet since it's not in my hands. I'm thinking of buying a new BB as well... but of course, this little project of mine is becoming not so cheap anymore! Any tips? What would you do?

Cool! So it's probably best that I buy a new crankset? I don't know what kind of BB the bike has yet since it's not in my hands. I'm thinking of buying a new BB as well... but of course, this little project of mine is becoming not so cheap anymore! Any tips? What would you do?

That's do-able but it will bump up the cost factor. Do you remember the song about a $10 dollar horse and a $40.00 saddle?

There's actually 2 different ways to do it:
1. Buy a BMX 3 piece crank.
2. Buy a press-in adapter and a cartridge road bike bottom bracket and crankset.

If you decide to keep the one piece crank you'll probably want a chainring in about the 40 tooth range.

Haha, yeah. Saving money is definitely important for me. Thanks for your tips!

I had an idea. I was at the bike co-op near me and they had 170mm cranksets for $21 (I'd like 165mm but I'll settle) and bottom brackets for cheap too (I'd probably by a 103mm?). It would still save me money.

Would that work?

I'd be interested to know, too. But I have little experience in trying to swap out a low-level Ashtabula for a 3-piece cotterless crankset. What kind of bottom-bracket does this crankset at the Co-op have?

Well, the co-op has a large variety of cranksets and BBs laying around. I'm very new at this stuff, so I didn't really have a close look at the BBs... I need to go back there. But I would think they have a bunch of different kinds. This is my first attempt at a fixed gear conversion so I'm really not too concerned about having great quality parts, I just want the bike to work :) My plan is to walk in, grab the crankset I want and find a BB that fits, hehehe.