Perfect for flatter courses and time trials, the DURA-ACE C60 prioritizes aerodynamic efficiency and lateral rigidity. The new hub design, stiffer spokes, and deep section rim are designed specifically to allow you to push harder in corners and ensure that every bit of your effort is translated into forward motion.Like the entire DURA-ACE wheel family, the new C60 started with a blank slate. Different from the C36 and C50, the C60 has a specific front hub design using Shimano´s OPTBAL 2:1 spoke pattern to enhance lateral rigidity. The C60 also receives stiffer spokes, 1.8 mm instead of 1.5 mm. Tested by our professional athletes, this focus on the lateral rigidity of C60 allows you to push harder in corners and when maneuvering at higher speeds. Lastly the new wind-tunnel tested, deep section rims feature a faster, more stable cross-section that time trialists, triathletes, and sprinters alike will enjoy.Features:- HR: High-Rigidity ver. +20% increased lateral rigidity for powerful riders and sprinters- 60 mm height full carbon rim- Internal rim width: 21 mmSpecifications:- Average weight: 751- Spokes_Straight pull: Yes- Brake type: CENTER LOCK disc brake- Axle fixing method: 12 mm E-THRU- O.L.D. (mm): 100- Thru axle (length x inner diameter , mm)_100 x 12: Yes- D2 rim: Yes- Disc mount_140 mm Disc brake rotor compatible: Yes- Disc mount_CENTER LOCK: Yes- Front/Rear: Front- OPTBAL (2:1): Yes- Reflector_AS: CATEYE RR-550-WUW SW- Reflector_DIN: CATEYE RR-317-WUA SW- Reflector_JIS/CPSC: CATEYE RR-550-WUW SW- Rim_Height (mm): 60- Rim_Requires rim tape: Yes- Seal_Hub: Contact- Spokes_Bladed: Yes- Spokes_Butted: Yes- Spokes_Number: 24- Tire_Recommended size: 25-622 - 32-622- Tire_Type: Tubeless- Wheel Size: 622 x 21C- Model name: WH-R9270-C60-HR-TL- Rim_External width (mm): 28- Rim_Internal width (mm): 21- Spokes_Diameter (mm): 2.0-1.8-2.0Technologies:D2:- Aerodynamic performance is affected by wind direction. To create the D2 rim, SHIMANO engineers considered both frontal and cross winds, aiming to achieve optimal performance in real-world riding conditions. Extensive prototype testing, in the wind-tunnel and on the road, proved that a wide rim shape with a deep tire bed performs best across a wide range of conditions. At yaw angles ranging from 0 to 15 degrees, the SHIMANO D2 rim profile reduces air drag better than others aero shape rims. This rim design also boosts lateral wheel stiffness and offers improved vertical compliance for increased control, comfort and durability on the road.OPTBAL:- The OPTBAL rear wheel spoke system features 21 spokes—14 on the drive side and 7 on the non-drive side. Cassette spacing in today's wheels produces unbalanced tension in traditional 1:1 spoke systems. This unbalance is intensified with the 11-speed cassette, producing nearly double the tension on the drive side spokes. Generally high and low tension spokes have respectively tendency toward breaking down and coming loose spoke nipples. Unbalanced tension affects durability and strength. The OPTBAL design rebalances spoke tension, enhancing wheel rigidity and strength for a more durable wheel.