Unfortunately, the crankset on my Motobecane 10-speed (probably a Nomade but am not 100% sure) has finally stopped being able to hold the chain when under a high load and so I need to find a replacement crankset as soon as possible, but I have no idea where I can find an affordable solution and how to recognize a crankset which would be compatible with my bike: I was quoted more than $140 from a bike shop for replacing the crankset and bottom bracket with brand-new ones, and I feel that this price is not worth it since I can nearly replace my entire bike for that much. So, what are my options, and who has a crankset which would fit my bike? (I'm of course more than willing to buy used parts as long as they're in good condition)

It's a double crankset with 52/39 teeth, a square bottom bracket and an 8-speed chain, but unfortunately I'm not sure what sort of threads the bottom bracket has (French, Swiss, "normal"?) because the crankset and bottom bracket have already been switched out once (when I bought the bike the old crankset was shot and had been replaced before selling it).


Thanks a lot for whatever help/advice you can render.