I know it's a scam, but what's the catch?

[smilingcat]

TsPoet's suggestion is excellent. Have the LBS check the stolen bike registries while they're at it.

+1 I was thinking "guy is pawning off an hot item on unsuspecting person". Make arrangements at LBS first then give the guy a call and meet him there. Safer in number and if he does no show then you know what it was about.

Did he leave his contact information with you? If he didn't then chances of the "105 bike" being hot goes way up.