TreeFrog L2 Front Wheel Holder For Elite 2/Pro 2 Bike RacksOverview: As the demand of the double bike racks has been keep growing, and many customers have been requested, we created the 2 Front Wheel Holder, which works with the Elite 2 and Pro 2 racks. It comes with a deck, 1 TreeFrog vacuum cup, placed at the center, 2 front wheel holders, which could carry 9mm quick release wheels, 12x100mm, 15x100mm and 15x110mm thru axle front wheels as well, with simply putting a standard quick release thru those thru