Newbie Bike Question

General rule of thumb for used bikes around here would be 50% of new price, less any obvious replacements needed. Don't know what kind of C'dale this is, but it looks pretty old to me. As a result, I'd be concerned about how much wear and tear is on the bike, including crash damage.

It's impossible to tell the condition from photos. If the bike needs a new chain and cassette, chainrings and tires, all normal wear items, you're looking at $250 or more. If you decide to look at the bike, suggest you should take someone with you who can do these basic checks, including brakes, cables, BB bearings, wheels/hubs, headset. Not hard to quickly check these things, but failure to do so could be expensive.

However, since the ad is short on details, I'd not even want to investigate. The seller should know and state the model and year, the size of the frame, etc....just basics. This lack of info would make me suspect the bike was stolen.

And of course size is all-important. Buying the wrong size bike is like buying the wrong size pair of shoes.