Combining the performance attributes of our new UST Road Tubeless system and purpose-built disc-brake technology, this new addition to the Ksyrium family is a versatile all-rounder for your most challenging road rides. The lightweight rims, engineered with our unique ISM 4D technology, are built wider with a 19mm internal width and 23mm external width. They are integrated with the new Yksion Pro UST tubeless tire to create a user-friendly tubeless system that makes it easy to install and remove tires. And the benefits of the Road Tubeless system are clear: lower rolling resistance and the smoother ride quality that comes with the ability to run lower tire pressure with a reduced risk of punctures. So you can ride faster, more comfortably, while expending less energy. Our extensive experience designing mountain bike disc wheels informed the engineering process of these wheels. Unlike a wheel with rim brakes, braking torque is distributed through the hub, spokes and lower rim before it reaches the ground. The braking load is also higher on the front wheel since the center of gravity is transferred to the front of the bike when itís decelerating. Thus, the front wheel needs to be overbuilt with more spokes (24 instead of 18 or 20), and those spokes need to be crossed on each side of the wheel to make sure brake torque is evenly distributed. The rear wheel also needs 24 spokes, but since the braking torque is generally lower, we use Isopulse lacing (radial lacing on the drive side) to maintain a better balance of the spoke tension, thus greater stability and stiffness. The front hub is convertible from 12mm to 15mm thru-axle or quick release. The rear wheel features the fast-engaging Drive 360 freewheel system. It comes with a 12x142 thru-axle and is convertible to quick release.