KTM is on a run. For years, the 450SX-F has been the lightest, most powerful bike in the class. Not that long ago, it was the only one with electric start and a hydraulic clutch, too. Now, centerstage is getting crowded with new bikes that have similar technology. In response, KTM did what it always does. The 2019 450SX-F is lighter and faster yet. The motor has a new, more compact head, the frame has been redesigned with more rigidity, the bodywork is new, and there are dozens of other changes. If that sounds familiar, it’s because it has similar changes to the 2019 Husqvarna FC450.