Built for road, triathlon, gravel, and cyclocross bikes, the ZEALA(R) Pro Road Bike Cover protects your bike while it travels on common rear vehicle rack styles. Patented pass-through engineering allows standard rack securing mechanisms to connect through the bike/cover setup, while waterproof materials and rubberized backing help shield your bike from weather, road spray, and paint abrasion. Each cover is designed to work on all the standard rack types similar to those shown. Available in two sizes: Medium is tested to fit most 48-54 cm road bikes and most 48-52 cm gravel and triathlon bikes. Large is tested to fit most 55-63 cm road bikes and most 53-63 cm gravel and triathlon bikes. For triathlon bikes, the cover includes an expandable handlebar box to accommodate aero bars and an expanded seat tube area for bikes with water bottle cages mounted behind the seat. Each cover includes pockets for the ZEALA(R) Pro Light Kit, sold separately. Note: ZEAL A(R) Pro Bike Covers are not recommended for roof racks.