My current bike: Specialized Diverge Comp DSW
For a duathlon, any bike is better than no bike. However, not everyone needs, wants or can afford a fancy triathlon (tri) bike. My first three duathlons were completed using a $350 Diamondback Trace Street Hybrid bike. With the right training, you can be competitive on whatever type of bike you own. If you are looking to test the waters before investing a lot of money AND you only want to own one bike, a gravel bike is a good choice for its value, versatility, adjustability, and upgradability.
First off, you might be wondering why not just go with an entry-level triathlon bike. While you may see many pro and amateur athletes on expensive triathlon bikes, you do not need one for a duathlon. Triathlon bikes, with steeper angles and aerodynamic positioning, can be a bit tricky to handle because they are made for going fast in a straight line. In addition, you are positioned more forward on the saddle, which can be uncomfortable and make it tough for new or inexperienced riders to comfortably AND confidently maintain a deep, aerodynamic position. Not to mention, triathlon bikes are not ideal for recreational or group riding because they are more difficult to maneuver since the brakes and gear shifters are located out on the aerobars.
So, what is a gravel bike? A gravel bike (also referred to as an all-rounder or adventure bike) is essentially a road bike designed for use on unpaved roads. Gravel bikes can be ridden almost anywhere from pavement to dirt to gravel (hence the name). Gravel bikes feature disc brakes, additional clearance for wider tires, and a lightweight frame with an endurance geometry which is not only more stable than traditional road bikes, but also allows them to adapt to everything from paved roads to rugged terrain for a smoother ride.
The frame for a gravel bike is compact, with a more relaxed geometry than the standard road bike. This makes them incredible accessible and easy to ride. Furthermore, the sizing on a gravel bikes is not that different from a common road bike. So whatever size you are riding on a road bike would be the same frame size on a gravel bike. In regard to frame material, can get perfectly capable gravel bikes in aluminum, steel, carbon, or titanium depending on how much you want to spend.
After the frame, the groupset is the next thing that you should look at. A groupset is a collection of mechanical parts that include the derailleurs, shifters, brakes, chainset, bottom bracket, cassette and chain. The three primary groupset manufacturers are Shimano, SRAM, and Campagnolo. All three manufacturers offer a wide range of groupsets at competing price points. The choice of groupset has a large effect on how the bike will perform. Most bikes generally come with a Shimano groupset (Claris, Sora, Tiagra, 105, Ultegra, or Dura Ace). For most, the 105 groupset is as good as it gets in terms of bang for your buck and there is no compromise in general functionality. Anything beyond that is helpful, but you’ll find the performance improvement in components gets gradually smaller the further their prices increase.
Another reason to consider gravel bike is that most are able to accommodate tire clearances for both 700c and 650b wheel sizes. The 700c standard is the classic road bike wheel size which you’ll find on most common gravel bikes with tire widths from generally 28 mm up to 40 mm. The 650b standard, usually in tire widths from 42 mm to 50 mm, offer a significant advantage in grip and comfort while absorbing the vibrations of off-road riding. Basically, when you put skinny road tires on a gravel bike, it will handle more like a road bike and when you put fat, knobby tires on, it will handle more like a trail or mountain bike. This gives you the option to invest in a multiple set of wheels: a 700c wheelset that is skinny and fast for road riding and a 650b wheelset with large, knobby tires for riding on rougher terrain. It’s like having two bikes in one.
Disc brakes have become popular for a variety of reasons. Disc brakes are standard equipment on gravel bikes and offer a marked improvement over rim brakes. Whereas rim brakes stop the bike by squeezing two opposing brake pads against the rim of the bike wheel, disc brakes use a round metal disc called a rotor at the center of each wheel and stop the bike by squeezing a brake pad against the rotor creating friction to slow the bike down. Disc brakes feature superior braking performance and stopping power, especially in wet conditions.
In short, a gravel bike can allow you to ride fast on all types of terrain whether you are training, racing, or recreational road riding. In addition, by making some adjustments such as adding clip-on aerobars and switching to aerodynamic carbon fiber wheels can help make a gravel bike more aero for duathlons. However, cycling performance is dependent on the person not the equipment. In short, it’s not the bike, it’s the person on it. Whatever bike you choose, you’ll adapt to it and tweak it to your needs as you become more comfortable and confident on it.