I've joined this site 'cause I like to restore bikes others are throwing away. Sometimes I find a bike I don't know anything about. This seemed a good place to research those bikes. I currently have a Schwinn SX aluminum bike that only has the serial marking "N" on the underside of the crank housing. There's also the number "6600" stamped on the Schwinn logo on the front of the bike. I can't find any info on the bike. I'll be looking through this site to hopefully find something about it. If anyone knows where I might find info, please let me know. Thanks.