Here I am, looking at your pic, and all I can say to myself is "That's a small front sprocket"...
Very cool, by the way. I used to take my cat for bike rides, have her sit on my shoulders, every so often she' slip off and be dangling by her leash inches above the road. I have since wisened up, do not worry. She no longer goes on bike rides with me. Although, I guess she could in a bicycle basket like that if she so desired...