I posted this in Catch of the Day, but wanted to see if the larger audience could steer me in the right direction. Because the pick up location isn't too far from me, on a whim I bid on two Motobecane Mirages and won them. I've searched the archives for serial number decoding, or catalogs so I could see if I can id the years. I'm gathering the Mirage was entry level in the Motobecane lineup, but, they seem like interesting bikes...(I'm digging the fenders...

Nice Motos...I have a Motobecane Nomade which was the entry level bike. The Mirage I believe is the next up in line.

The Nomad is such a strong bike though.
I did some good damage to a Camaro in 1986 with one of them.

Motobecane serial numbers, contrary to some things you'll read on the internet, aren't too useful. Your best bet is to look at a hub, derailleur, crankarm, or chainwheel (or all of the above) and look for a 2-digit date code. Normandy hubs have a date of manufacture stamped in plain sight - the month and year are shown. Checking all the numbers should help you narrow down the model year of your bike.

Let us know what you find, and give me a shout if I can help on threading issues.