I want to get my dd a secondhand islabike or a frog. I can't get my head around what size isla I should get her. She will be 5 in late November and she is currently 107cm tall with an inside leg of 47cm. I don't want to get her a bike that she'll outgrow in a few months but at the same time I don't want to get her one that is too big for her. Ive checked the sizechart on islabike website, but i am still unsure. Any advice will be greatly appreciated. Thanks