The Pro Rear Wheel Holder has an upgraded ladder-strap and a wider rear wheel housing supporting mountain-bike tires. It is also a great additional product for the Crossbar to turn it to a bike rack. With the right fork mount attached to the front Crossbar, and Rear Wheel Holder, you are able to transport bicycles with different wheel bases, without using the rear crossbar.
All the Pro bicycle racks come with the Pro Rear Wheel Holder
The cup’s diameter is 15cm.