The Roar
The Roar


Braking Bad: Do discs belong in the pro peloton?

Do disc brakes have a place in the professional peloton? (Source: AP Photo/Mark J. Terrill)
Roar Pro
17th December, 2015

There’s been a lot of talk recently about cycling’s governing body the UCI extending a trial of disc brakes, conducted back in August and September, into 2016.

Disc brakes, as opposed to the traditional rim brake, are de rigueur for mountain and cyclocross bikes, so what’s all the fuss about allowing them out on the road?

For starters, disc brakes simply offer better stopping power, especially in the wet. The disc, or rotor, sits close to the wheel hub keeping it relatively dry and clean. On rim brakes, the stopping surface is close to the road and picks up moisture and grime reducing the grip of the brake pad. This can be quite pronounced on carbon fibre wheels.

Another advantage of placing the brake at the hub is that removing the rim calliper mechanism frees up space to run wider tyres. Disc brakes also eliminate the problem of brake pads rubbing on the rim due to flex in the wheel when the bike is thrown side to side under hard acceleration on a tough climb.

Hydraulic disc brakes, in particular, offer better ‘braking modulation’, which gives the rider better feel and control when squeezing on the brake lever and is a real plus in the wet without having to allow for a slick rim.

Some big ticks there for disc brakes, but they do have some drawbacks.

Disc brake units tend to be a little heavier and with the UCI signalling lifting the current 6.8 -kilogram minimum weight limit, professional teams will be conscious of factoring this in in their quest for ever lighter machines.

The mix of disc and rim brakes during the trial period and possibly beyond will require neutral service vehicles carry both kinds of wheel, which could lead to fumbled wheel changes costing valuable time. Also extra care must be taken to fit a disc wheel properly to avoid the rotor rubbing on the pads.

That leads us to the problem of rotor heat dissipation, which can be an issue with hydraulic systems. Heat caused by friction can transfer to the fluid causing ‘brake fade’, reducing its efficiency, and in extreme cases complete brake failure. However, this is only likely to happen with constant heavy braking on a long descent.


Now your average professional cyclist is not going to be spending a lot of time on the levers, so it’s unlikely we’ll be seeing rotors glowing white hot at the bottom of a big descent like a heat shield on a space craft re-entering earth’s atmosphere.

Then there’s the question of stopping safely with teams running different brake systems.

Differences in stopping distance may lead to more crashes in a tightly bunched peloton. BMC Racing’s Philippe Gilbert also fears the sharp edge of the rotor could “open up” a rider in a big shunt.

But let’s step back here before we dismiss the idea of disc brakes on the grounds of safety because of the potential of an innocuous looking disc transforming into a ninja throwing star of death.

A crash in the peloton is rarely a pretty thing when you consider riders only have a millimetre of breathable fabric and a foam esky with a polycarbonate shell on their head for protection. In a crash, there are many different elements that can cause bodily damage, so if we want to get serious about safety perhaps we should eliminate forks, spokes, derailleurs, handle bars, chain rings, other riders, and the road.

After all that the safety risk posed by brake discs is small beer in comparison.

Lastly, there’s the question of aesthetics. We all want to our bikes to look good, right? Disc brakes look right at home on a rugged mountain bike, but on drop bar bikes?

I’m reminded of a TV ad going back some years for a depilatory product where the actress proclaimed something along the lines of “moustaches look great on guys, but on girls?”. That’s been my reaction to disc brakes on sleek road bikes.


But after seeing discs on cyclocross bikes, which don’t look that much different to their roadie cousins, I’m beginning to warm to them.

No doubt as technology improves so will the looks, and wouldn’t bike component manufacturers love to see their flash looking disc brakes in the pro peloton; if the pros are using it chances are the regular punter will want to too.

It will be interesting to see how the trial pans out. My feeling is that concerns will be put to rest and riders will embrace this innovation as they have with clipless pedals and electronic gear shifting.

Then we can get back to the real issues in cycling, such as socks up or down, and should sunglasses be worn with the arms inside or outside the helmet strap?