Great event & volunteer participants
For bike valet, I would suggest that at least 1 staff member be onsite for assistance. One who knows exactly how the racks are supposed to be set up as there were times when the racks were very unstable. The second day should definitely have extra help given the number of participants who bring their bikes and communication should be conveyed that if they leave their bikes they will be charged a fee. Additional signage maybe necessary stating that bikes are not to be left at the bike valet.
I would digest having more people for bike valet also to have some kind of flow to help things run smoother much like you do for the expo

