I've never sold my bike. But I would probably do it on Craigslist so that you don't have to worry about shipping.

Some people sell their bikes on Craigslist and then meet at a bike shop (instead of your house) so that the buyer feels more confident that you are not selling them a crap bike.
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2012 Specialized Amira Elite, upgraded carbon handle bars, Jett saddle 143mm switched to 145mm 2012 Selle Italia Max SLR Gel Flow saddle

2011 Specialized Ariel Sport,suspension post,Serfas Rx Women's Microfiber saddle