Bikes with unknown owners have been mainstay fodder for the Dawn Joggers. There was one bike that stayed mysteriously tethered to a post at the corner of Sand Hill Rd and Oak Avenue for years. Other bikes on the Stanford campus would appear and then disappear. The criteria for all mystery bikes is that they aren’t in bike racks – and that they are parked where one would normally park a bike. They get extra points for having a jaunty design. When the female DJ spotted a particularly sporty bike – notice the lacework! – at Lake Lagunita this morning, she realized she hadn’t seen a random bike in quite some time. But finally one appears…