We are also doing horseback riding and swimming, along with dance classes, but no luck yet riding a bike. It seems to be the peddling motion that is difficult for her. I can't tell about balance on the bike since she has training wheels but still can't seem to make it work. Interestingly she can post on a horse while doing all sorts of things with her arms (i.e. flapping them like a bird) so I wonder if it is a left/right coordination issue.

She has asked for a pogo stick for Christmas and I found one with a large area to balance on. I'm wondering if that may help. We have an OT appointment next week - maybe I'll ask about the bike riding and see if she has any ideas. We got the same core strength explanation as LNEsMom.