What about lost bikes? In the past, Burning Man's efforts to re-unite lost bikes with owners met with little success, measurably less than the effort expended. The same crew who maintains the hundreds of Community Yellow Bikes also collected hundreds of abandoned bikes post-event. They are based in Reno, NV. You can write them at lostbikes (at) burningman (dot) com with a description of your lost bike.
Unclaimed items, including bikes, will be donated to charity, or otherwise put to good use.
So--send them an email, as well as making an ePlaya post.
More tips are available here:
http://www.burningman.com/blackrockcity ... standfound
The best of luck to you.