And how much of a risk will there be at this event for the theft of a bike helmet? If the risk is low, I think it would be far preferable to lock the helmet to your bike than to walk around with it in your hands. That just sounds kind of awkward at a social/work event. Otherwise, I don't see any real issue with your riding to the event so long as you can dress appropriately. But if it's just going to make you feel a bit uneasy or self-conscious once you're there, then just take public transit. That sounds like a pretty viable option, too.