Features:

• Handy tube adapter designed for vehicles with rear hitch racks
• Ideal for bikes with funky top tubes that don't mount properly on rack
• 1 molded collar attaches to bike stem and other collar mounts to seat post
• Large diameter tubing and anti-rotation inserts for maximum stability
• Works well with women's frames and dual-suspension bikes

Editor Reviews:

Product Description:
The Yakima Top Tube Frame Adaptor connects easily between a bike's seat post and handlebars. This allows much easier loading and transporting of bicycles that don't have a top tube frame that runs straight between the handlebars and seat post. Many rear hitch mount bike racks require this feature while the trunk mounted bike racks are simply easier to use for top tubeless bikes that have the Yakima Top Tube Adaptor attached.

Amazon.com Product Description:
Does your bike's top tube prevent you from mounting your bike properly on your rear hitch rack? Turn to the Yakima TubeTop adapter, which keeps your bike mounted solidly on single or dual mast mounts. The adapter installs directly on your bike, with one molded collar attaching to your bike stem and the other to the seat post. Once installed, the adapter's large diameter tubing and anti-rotation inserts will sit sturdily on your vehicle's hitch rack, letting you tote everything from women's frames to dual-suspension bikes.

Rating : - can not fit my 24" mountain bike
I purchased it on Amazon for my wife's 24" mountain bike. Even in its shortest length, it is still too long to secure between head tube and seat pole. Need to return it. Amazon needs to have much more clear description (especially working length) for this item.