The popularity of dual-sport bikes has held steady since the late 1960's (when they used to be called enduro bikes), and with good reason; dual sport bikes are relatively inexpensive, very versatile, and offer excellent fuel economy. Deciding which is the best dual sport bike to buy can be confusing given the large number of bike models on the market, but buying an on/off road bike isn't much different than buying any other bike. It all boils down to identifying a few key components.
Off-road trails: The first step when choosing a dual sport bike would be to assess the main off-road trails you'll be riding. The on-road part of the equation isn't as critical because it's easier to ride a motorcycle on smooth pavement than on rough off-road trails so the off-road aspect is the prime consideration. Wide open fire roads and logging trails won't be much of a problem for any size dual sport bike, but if the off-road trails you'll be riding are tight technical single track trails, you'll have a much tougher time maneuvering a big 650cc bike on the tight trails than you would on a smaller 250cc. You'll also need to consider how long your journey will be. A smaller bike would be perfect for a short trip during the summer, but you'll need a more substantial bike if you're planning a longer trip.
Bike weight: The next consideration would be your height and overall size and strength. Dual sport motorcycles are a compromise of functionalities and give up a certain amount of off-road performance in order to be ridden on the street, as well as sacrificing some street performance to allow them to be ridden off-road. One of the compromises affecting the off-road side is additional weight. Although you might drop the bike on the pavement now and again, you will almost certainly drop the bike out on the trails and when you do, what goes down must come up, and you'll be the one doing the lifting. Dirt bike trails aren't flat like pavement, so you might be lifting the bike up on a steep hillside, muddy gully, or slippery gravel bed. The larger the bike, the more difficult it will be to lift the bike.
Experience: Your riding experience should also be considered, and if you're a total beginner stick with one of the smaller bikes. If you're too tall for the 250cc bikes, try the Husqvarna TE 310, or the Suzuki DRZ 400. You can always trade up to a bigger bike down the road but if you choose a bike that's too big and heavy, chances are you won't enjoy riding and may not stick with it (and may even get hurt).
Cost: Your wallet will also have a say in the final outcome but fortunately, dual sport bikes are relatively inexpensive considering the convenience, durability, and versatility they offer. The 2018 Honda 250L is listed with an MSRP of $5,149 while the 2018 Kawasaki KLR 650 has an MSRP of $6,699. Buying used is also an option, and since the dual sport bikes aren't subjected to the same punishment that a motocross or off-road trail bike endures, it's usually easier to find an on/off road bike that's in decent condition.
Making a dirt bike street legal: If you're thinking about taking a trail bike and trying to make it street legal, make sure you look into your State's DMV requirements beforehand. It may not be possible to make the trail bike street legal, and also might ending up costing you more in aftermarket parts than if you bought a dual sport bike right from the start. Each State has different rules, but you'll probably need some combination of mirrors, horn, turn signals, speedometer, head and tail lights, quiet muffler, spark arrestor, chain guard, DOT approved tires, and license plate holder.
Dual sport bike rentals: Your best bet is to rent a dual sport bike for a day or better yet, sign up for one of the many tours offered by off-road tour companies if you can afford it. Motoquest has been around for a while and they offer off-road tours in several locations, including an off-road tour of Alaska, which is a very popular dual sport riding destination. Eagle Rider caters more to the Harley-Davidson street rider, but they also rent dual sport bikes such as the Honda 230L, Kawasaki KLR650, as well as the larger BMWs and KTMs. If you're lucky enough to be going on a dream vacation to Hawaii, Maui Dual-Sport offers tours through the rainforest that sound awesome. Use 'dual sport adventure tour' (or something along those lines) coupled with your State to get more localized dual sport adventure tours and dual sport rental results.
Dual sport bike comparison video: The following video highlights the 2019 crop of dual-sport bikes just hitting the market. The second video shows the 2016 Zero Dual-Sport Electric Bike.