The Honda Grom is a great little bike, but it's not really meant for highway riding. It's got a 125cc engine, which just isn't enough power to keep up with traffic on the highway. Additionally, the Grom is only designed for use on paved roads - so if you take it onto the highway, you'll be putting yourself and your bike at risk. So while you technically can ride a Grom on the highway, it's not really advisable.