Thule 981 Bike Frame Adapter For Hanging Bike Racks Thule 981 Bike Frame Adapter allows ladies bikes, BMX bikes, mountain bikes and some kids bikes without conventional top tubes to be transported easily on Thule and other brands of bike rack, where the bike hangs from arms. It clips between the seatpost and handlebar stem, or headtube, to create an artificial top tube. The 981 Frame Adapter adjusts with a telescoping action between 400mm and 800mm in length, but may not be suitable for use on small childrens bikes. Free Mainland UK Delivery.