Bicycles and a few other fast moving things like joggers, seem to drive Sierra to distraction. We're not sure what it is about, but we first saw it during the winter in the off leash parks when we ran into the very occasional biker or jogger. One thought is that she has some herding instinct like a Border Collie. Once they stop then there is no problem, so it seems to make some sense. We have been working with her by riding a bike along the road as she walks on a loose leash. We also take her to a local bike and skateboard park using the Halti and as much distraction with treats as possible. It seems to be slowly working. She is ok with the bike riding along, and only gets somewhat somewhat agitated when it goes out of sight -- perhaps like losing track of the sheep!?
Today we took one further step and tried riding the bike with her on a loose leash. While at first she was preoccupied with the front wheel and wanting to get in front and bite it, she seemed to quickly adapt to the faster pace loose leash walk. Video below on the ride in the crescent. Hoping that frequent rides like this will be another step in getting her to forget her Border Collie genes!