Disc brakes have been the default braking system for mountain bikes for a decade and are now frequently seen on road bikes, despite the fact that pro bike races ban them. Triathlon, however, doesn’t follow the same rules as professional cycling (with the exception of draft-legal ITU events), and bike manufacturers are taking advantage of that fact, launching discs on some of the most highly anticipated new-for-2017 tri bikes. Consider these four things before making the investment.
Better braking performance
Disc brakes boast superior braking performance in both wet and dry conditions—no one contests that fact—and that’s a really compelling reason to make the switch. If you have ever ridden a bike with carbon wheels and rim brakes in the rain, you have probably noticed that the braking performance is usually pretty poor. Disc brakes work almost as well in the wet as they do in the dry, with aluminum or carbon rims, leaving you in better control of your bicycle. While it is true that most triathlons don’t take place on courses with technical, high-speed descents, you do have to make it to race day in one piece, and disc brakes make your bike safer. Disc brakes also usually require a very light squeeze of the lever to actuate, something that triathletes might appreciate after a cold swim or in a cooler race.
Over the last few years many bicycle manufacturers have designed their own, frame-specific, rim braking systems that have better aerodynamic efficiency than traditional rim brakes. These proprietary braking systems are often troublesome to adjust and lack the stopping power of traditional rim brakes. Disc brakes certainly don’t look as aerodynamic as these sleek and integrated brakes, but looks can be deceiving.
When a bike is designed from the ground up to incorporate disc brakes, bike designers are free to engineer the bike in ways that minimize the aero penalties associated with the brakes. The typical location of a front rim brake is difficult to manage aerodynamically, so locating the brake elsewhere has big advantages and allows designers a little more design flexibility. “Where rim brakes used to constrain frame and fork shapes, we’re now free to engineer shapes that significantly improve aero performance,” says Damon Rinard, chief engineer at Cannondale.
Parlee Cycles was the first company to announce a disc brake-equipped tri bike for 2017, and Tom Rodi, sales and marketing manager at Parlee Cycles, says disc brakes can actually make a bike more aerodynamic. “Disc brakes allow for slightly better aerodynamics because more of the cabling can be hidden and the leading edge of the bike can be made cleaner,” he says. Wheel designers are echoing similar sentiments—Enve Composites, on its website, says that disc brakes allow them to reduce wheel weight and to improve aerodynamics since a flat braking surface on the rim isn’t necessary.
Many triathletes often groan at the thought of changing from their heavy duty alloy training wheels to their carbon race wheels because of the need to change brake pads and adjust the brakes for different rim widths. Disc brakes eliminate this problem altogether, making wheel swaps much easier.
The largest drawback is the cost of buying a new fleet of disc brake race wheels if you are already invested in rim brake race wheels because the two types of wheels are not interchangeable. (Note: The disc brakes themselves don’t have a notable price difference when compared to rim brakes.) Since disc brake road bikes have been around on the road market for a few years, there are plenty of high-quality disc brake wheels to choose from, as well as new aero disc brake wheels available from many manufacturers, such as Zipp, Enve and HED. (In fact, HED and Zipp even have disc brake-compatible disc wheels now.) And while it may take some time to familiarize yourself with disc brakes, you can lean on your local bike shop tech, who is likely versed in the braking system.
Will disc brakes completely replace rim brakes in the transition area? Probably not immediately (or ever), but there will definitely be more of them on the transition racks soon. At a minimum, triathlon bikes won’t be any slower for incorporating disc brakes, and in the near future they might be the faster, safer and less problematic choice.