DISC-BRAKED RACE BIKES
We test six £2750-£3500 disc brake-equipped race bikes that can stop as fast as they go
While the disc brake experiment continues among the pros, in this test us mere mortals get to enjoy their stopping prowess without spending a fortune.
The official racing rule makers can’t decide whether disc brakes should be allowed or not, but, for the rest of us, top manufacturers have created disc brake versions of their competition bikes just in case. Even more relevant for most of us, they’ve made more cost-effective versions so you don’t need a pro team budget or a title sponsor to saddle one up.
Matching lightweight or aero frames for smashing the climbs and dominating drag strip sections with powerful, precisely controlled, disc brakes makes a lot of sense too.
However, the thin, tall, teardrop tube shapes that work best for straight line drag reduction are hard to reconcile with the other structural demands on a bike frame. They’re not the most efficient or predictable handling in crosswinds, which is why the Scott and Merida here use tube forms where the ‘tail’ of the teardrop has been chopped off flat. The idea being that the resulting vortex of swirling air behind the blunt face creates a ‘virtual’ tail, smoothing overall airflow. This ‘tail’ moves under the influence of crosswinds too, making it more drag efficient and less likely to get blown around. Frame designers can also use wider, more weight/stiffness efficient, squarer tube shapes rather than large, heavy and potentially gusty full fin designs.
Disc brakes offer an increase in stopping control, especially in bad weather, but successfully fitting them to a frame and fork isn’t easy. They move braking loads to the furthest ends of the chassis, which are typically the skinniest and most flexy. They need to retain as much of that flex as possible for a comfortable ride, while still being stiff and strong enough to cope with extra load at the end of long levers. Bigger, stiffer thru-axle dropouts potentially make this balance even harder to achieve.
That’s why we see so many different - often asymmetric - disc frame designs. On the bright side, hydraulic disc hoses can be contorted through much tighter twists and turns than conventional cables. There’s no restriction on tyre size and no need for rim brake mounting/ reinforcing stay bridges with discs.
But does adding weight and stiffness to cope with braking stress to the fork and frame create too much of a compromise in ride quality? Can a bike be competitively aero with rotors and callipers disturbing airflow? How much extra weight does a disc brake system add and does that noticeably affect the ride? These were the main questions we wanted to answer by taking six cutting-edge competitionstyle, disc brake-equipped bikes and blasting them around the hills and valleys of the Yorkshire Dales in challenging late December/early January weather. So, which of our disc jockeys are best suited to the conditions, and are we now total disc converts or happy to return to rim brakes now testing is done?