It's no secret, triathletes are renowned for spending huge amounts of time and effort dialing in their bikes in search of the perfect ride. All manner of frames, components and wheels are tirelessly investigated for what will hopefully yield the ideal bike setup.
When considering the myriad options out there, the greatest emphasis is placed on bike fit and optimal positioning. Diamondback's Custom Studio is perhaps the latest example in fit targeting, and central to this is ensuring the ability to pedal both comfortably and sustainably for the duration of any event. No bike is worth the investment if it doesn’t allow the rider to maximize his or her power output, so fit is crucial.
But part of proper bike fit also plays into aerodynamics. Besides gravity, wind resistance is the biggest force that triathletes need to overcome on the bike. Millions of dollars have been spent researching, developing and marketing the aerodynamic properties of cycling gear. It came of age a number of years ago with the advent of the so called ‘Superbikes’, those highly stylized, integrated machines that all claimed to offer the user the best overall aerodynamic performance for any given wind condition.
Rachel McBride dials in her bike before heading to Cozumel
This year we’ve seen the evolution of the Superbike, one that considers not only aerodynamics and storage options, but also something that has taken a backseat to economizing forward momentum, and that is braking. The introduction of disc braking to the world of triathlon is now the talk of the industry, and as with other cycling segments, there’s an amount of doubt and reluctance in the marketplace.
All things being equal, no one seems to question the effectiveness of disc brakes on the whole. The skepticism comes to the fore when the topic of aerodynamics is raised, and many assume that good old-fashioned rim brake bikes must be faster because manufacturers have to date spent considerable efforts to hide brake calipers from the wind.
Hiding rim brake calipers helps, but it is not the aerodynamic end-all
While it may be true that rim brake calipers have been tucked into leeward positions on many bikes in an attempt to minimize drag, rim braking still brings with it undeniable aerodynamic limitations when considering one of the most important aspects of the bike—the wheels.
Old Reynolds rim brake profile with flat brake track vs new, aerodynamically superior disc brake rim
Rim brakes rely on the sidewall of the rim to provide a surface for the pads to engage when a rider pulls on the levers. This constrains both the shape and dimensions to which the rim can be constructed in order to facilitate proper brake function, something already hampered in many cases by sub-optimal, proprietary brake designs.
Disc brakes remove the limits on rim construction because there is no need to incorporate a brake track. Removing the constraints mandated by rim brake tracks opens the door to creating entirely new rim shapes. Throwing out the old playbook grants designers and engineers a blank slate on which they can draw however they chose in seeking to improve airflow management and explore new relationships between drag and lift.
But given the bulky nature of current disc brake calipers and the surface of the rotors themselves, some question whether aerodynamic gains at the rim are erased by the addition of new components. Early testing reveals that there is aerodynamic parity between rim and disc brake bike systems. The improved rim shapes are effectively able to offset the increased drag of the disc brakes themselves, and in some instances out perform rim brakes in testing at certain apparent wind angles. And this is before frame and brake manufacturers have been able to develop true, aerodynamically optimized systems.
Reynolds new AERO wheels improve lift/drag ratios and crosswind handling over previous rim brake models
So while it’s still early days for disc brakes in triathlon, it’s clear that this is a topic that will see exhaustive testing and analysis in the coming months and years. But in spite of the hair-splitting aerodynamic question, the reality is that disc brakes simply work better than rim brakes, and stand to improve overall triathlon bike safety and performance. They are reliable in all conditions and offer modulation far beyond any rim brake. Mountain biking made the switch years ago, cyclocross is in transition now, and the pro road peloton will complete its migration by 2018 after clearing its political hurdles. Triathlon tends to span technology gaps far quicker than other cycling disciplines, and disc braking is set to be the next bridge crossed.
When considering the myriad options out there, the greatest emphasis is placed on bike fit and optimal positioning. Diamondback's Custom Studio is perhaps the latest example in fit targeting, and central to this is ensuring the ability to pedal both comfortably and sustainably for the duration of any event. No bike is worth the investment if it doesn’t allow the rider to maximize his or her power output, so fit is crucial.
But part of proper bike fit also plays into aerodynamics. Besides gravity, wind resistance is the biggest force that triathletes need to overcome on the bike. Millions of dollars have been spent researching, developing and marketing the aerodynamic properties of cycling gear. It came of age a number of years ago with the advent of the so called ‘Superbikes’, those highly stylized, integrated machines that all claimed to offer the user the best overall aerodynamic performance for any given wind condition.
Rachel McBride dials in her bike before heading to Cozumel
This year we’ve seen the evolution of the Superbike, one that considers not only aerodynamics and storage options, but also something that has taken a backseat to economizing forward momentum, and that is braking. The introduction of disc braking to the world of triathlon is now the talk of the industry, and as with other cycling segments, there’s an amount of doubt and reluctance in the marketplace.
All things being equal, no one seems to question the effectiveness of disc brakes on the whole. The skepticism comes to the fore when the topic of aerodynamics is raised, and many assume that good old-fashioned rim brake bikes must be faster because manufacturers have to date spent considerable efforts to hide brake calipers from the wind.
Hiding rim brake calipers helps, but it is not the aerodynamic end-all
While it may be true that rim brake calipers have been tucked into leeward positions on many bikes in an attempt to minimize drag, rim braking still brings with it undeniable aerodynamic limitations when considering one of the most important aspects of the bike—the wheels.
Old Reynolds rim brake profile with flat brake track vs new, aerodynamically superior disc brake rim
Rim brakes rely on the sidewall of the rim to provide a surface for the pads to engage when a rider pulls on the levers. This constrains both the shape and dimensions to which the rim can be constructed in order to facilitate proper brake function, something already hampered in many cases by sub-optimal, proprietary brake designs.
Disc brakes remove the limits on rim construction because there is no need to incorporate a brake track. Removing the constraints mandated by rim brake tracks opens the door to creating entirely new rim shapes. Throwing out the old playbook grants designers and engineers a blank slate on which they can draw however they chose in seeking to improve airflow management and explore new relationships between drag and lift.
But given the bulky nature of current disc brake calipers and the surface of the rotors themselves, some question whether aerodynamic gains at the rim are erased by the addition of new components. Early testing reveals that there is aerodynamic parity between rim and disc brake bike systems. The improved rim shapes are effectively able to offset the increased drag of the disc brakes themselves, and in some instances out perform rim brakes in testing at certain apparent wind angles. And this is before frame and brake manufacturers have been able to develop true, aerodynamically optimized systems.
Reynolds new AERO wheels improve lift/drag ratios and crosswind handling over previous rim brake models
So while it’s still early days for disc brakes in triathlon, it’s clear that this is a topic that will see exhaustive testing and analysis in the coming months and years. But in spite of the hair-splitting aerodynamic question, the reality is that disc brakes simply work better than rim brakes, and stand to improve overall triathlon bike safety and performance. They are reliable in all conditions and offer modulation far beyond any rim brake. Mountain biking made the switch years ago, cyclocross is in transition now, and the pro road peloton will complete its migration by 2018 after clearing its political hurdles. Triathlon tends to span technology gaps far quicker than other cycling disciplines, and disc braking is set to be the next bridge crossed.
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