Amongst the avid skeptics of disc brakes, I was once a one of the most stubborn. I had countless debates with other riders, tech journalists and cycling industry figures where I defended my long held position: discs were heavy, too powerful, too expensive, unrefined in design and altogether a marketing gimmick. [For the main argument against discs, click here].
Today, disc brakes still add weight, they still add cost and there’s still a need to refine the design. After a decade of reviewing bikes, though, I can’t help settling on an inescapable reality – disc brakes are simply better.
However, let me qualify myself. I’m in no position to say what is better or worse for pro riders. They know a lot more about WorldTour cycling, and their own mechanical requirements, than I do. When I say discs are better, I mean for the vast majority of consumers of high-end road bikes. These are usually not professional riders.
Firstly, though, let’s talk about the downsides.
Jamie Wilkins’ case against discs (the first of our two-part debate) was very well argued, and he was right. Discs make bikes heavier, rim brakes can offer sufficient braking, and the technology still has some ground to improve, while rim brakes are virtually at an apogee of technological progress.
Similarly, when Chris Froome reviewed his Factor Ostro VAM, he made some very good points about the overall technical limitations of disc brakes. True, disc rotors are inclined to rub against the pads with even the slightest misalignment – I’ve had countless conversations with other tech journalists about why piston travel can’t be far greater as standard to reduce this. With modern groupsets you can adjust this to an extent, but it’s far from the technical ease with which you can immediately adjust all elements of a rim brake setup.
Chris was skeptical about the use of disc brakes on the Factor Ostro VAM
Froome was also on the money when it came to disc rotor warping. This is a frustrating reality. As is piston retraction, which can be a real issue when travelling if you fail to place a spacer between the brake pads.
As someone who was once obsessed with every watt, the early disc brake bikes of eight or nine years ago drove me mad. There's nothing more demoralising when working to keep pace on a chain gang or long climb than that relentless, mocking rub of pad on rotor.
To Froome’s list, I’d also add the frustration of controlling the actual pinch point of the brake lever. Yes, new hydraulic groupsets do offer easy adjustment to the lever throw, but not to the actual point at which the lever engages the brake.
My counter to all of that, though, is that rim brakes often simply don’t work. At all.
Yes, with the right brake pad compound and a very good carbon rim, you can expect good braking even in wet weather. Diverge slightly from that, though, and you have the sort of white knuckle one-foot-unclipped adventure that many of us will be familiar with when descending on carbon rims in a downpour.
I’ve been unfortunate enough to experience a few of the other old wives’ rim brake tales firsthand too. I’ve had a carbon rim delaminate (effectively come apart) on the descent of the Honister Pass. I’ve had a tyre blow up due to heat build after dragging my brakes a little too much. I’ve also completely stripped the treated carbon braking surface off a carbon rim during a rainy road race.
Carbon rims have benefitted hugely from the introduction of disc brakes
On discs, by contrast, I’ll never forget descending the Mortirolo one scorching July day six years ago, when the rider directly in front of me misjudged a corner and ploughed into the armco. It was one of my first big descents on disc brakes and to my amazement, I found myself able to reach a complete stop centimetres away from him.
While many would argue that rim brakes can perform as well as disc brakes in the right conditions, few could argue that in pure mechanical braking terms that rim brakes are in any way superior. We could talk about torque and moments of force, brake pad compounds and hydraulic fluid, but really all that matters is that disc brakes are better at braking. So, the question is do we want better brakes?
For pro cyclists, those benefits are likely less appealing. Their descending skill puts them at the limit of tyre traction, not braking power. So there’s little to gain from the extra power of discs. Equally, a little disc rubbing is annoying for me, but it’s potentially career-ending for a WorldTour rider. Discs, for them, are a tough sell. Many, if not most, of them seem to be slowly converting, though.
Julian Alaphillipe and Peter Sagan are two riders who have converted to discs (Photo: SWPix)
Yet, how relevant is this to most riders? If you really want to emulate the pros, then spend a season riding tubular tyres. Remember, too, that each team has access to hundreds of wheelsets from their equipment sponsors when you come to assess the damage to your carbon rim’s brake track after a season of riding.
Which boils down to the heart of the problem, the ever-growing divergence between the bikes pro cyclists ride, and those that normal cyclists want. Much like trying to drive an F1 car on country lanes on a sunny Sunday, it doesn’t take long to realise that not every bike designed around WorldTour riders competing on closed roads will suit the purpose of even the most competitive amateur.
Then there's the question of the type of riding we want to do. I really enjoy riding quickly, but I also love to ride on gravel and mixed terrain rather than simply on the road. Rim brakes have always been a mechanically limiting factor in tyre clearance of road bikes. Switching to discs has enabled WorldTour race bikes to extend their tyre clearance to a comfortable 32mm – the sort of tyre compatibility we’d expect from the cross bikes of yesteryear. That’s not to mention wider rims offering more aerodynamic stability (I’ve been blown across the road by many an early V-shape aero rim).
In future, we’ll see the technical issues ironed out, the weight drop ever further, improved aerodynamic rim designs and just far, far more versatility. To complete the picture, all we need is a 1x groupset with a 10-50 cassette (OK – that’s a step too far).
Ultimately, large technological shifts often bring about compromise. Professional photographers took a decade to convert from film to digital cameras. And, of course, some of the world’s best photographers still take photos on film.
Every year, more and more road bikes come equipped with disc brakes, and in five years time you’ll be hard pressed to buy a bike without them. But that isn’t because of an industry conspiracy. It’s because consumers want them. To me, that’s a good thing.
Looking back over all the bikes I've ever tested, the best have all had disc brakes attached to them – the S-Works Tarmac SL6, the Parlee Z-Zero, the Colnago C64 were all better for the addition of discs. Their disc brake versions took all the character, speed and ride quality of their rim brake version, and simply made them stop faster and accept wider tyres.
That said, cycling is a sport of tradition, and most of that tradition has excluded disc brakes. The top of the sport may continue to do so for some time. I’m just as susceptible to that traditionalism as the next fan – I can’t help longing to settle down with a classic steel frame with a chrome groupset, custom hand built wheels and a set of rim brakes.
But could I pretend, in pure performance, that it wasn’t worse off for missing a set of disc brakes? Sadly not.