From the conversations I have engaged in with manufacturers, shops, mechanics and riders, it looks like the lines have been clearly drawn - Rim brake vs. disc brake. The rim brake has been around a long time, is simple and reliable, however, it is not the most efficient method of stopping a bicycle wheel. The disc brake has all of these qualities of reliability and simplicity as well, but it is an incredibly efficient way to stop a bicycle wheel.
For the record, I hate to call the rim brake a caliper brake (as many people do), as disc brakes have a caliper, too. I always knew discs were the way to go, and I have been a vocal proponent for a long time. What really got me to put fingers to keyboard on the subject was an article on the Colnago C59 in the November 2012 edition of Bicycling Magazine. The article makes a good case for road discs, and it also made a good read of the C59, as well.
However, where the article went off the proverbial rails a little bit were in the areas of the UCI “Evaluating the benefits of road discs,” and the perceived issue of “Boiling brake fluid.” While the former is preposterous, the latter is complete nonsense.
Case in point: If MotoGP World Champion Casey Stoner can haul his Honda RC212V, 1000cc motorcycle down from 200 MPH, with Carbon rotors utilizing carbon brake pads, all without burning up his brakes or boiling the fluid, then how on God’s Green-Earth can even a 200 pound bicyclist produce enough energy to induce the opposite? Whether a hydraulic or cable-actuated bicycle disc system, there simply is not enough energy to completely fry your brakes – In my opinion.
As for the UCI, if safety is so paramount (as the article stated), then why in the heck have discs not yet been thoroughly evaluated and standardized? In this regard, I completely concur with Ernesto Colnago that this is, above and beyond all, a safety issue. And, who would know better than Mr. Colnago?
The article also alludes to some kind of mythical “Learning Curve” with this new, never-before seen technology (heavy sarcasm intended). Please, are riders really that dumb? In fairness to the articles author, well if someone is, then they best not be riding a bicycle outdoors without a helmet and an airbag.
Almost everyday now, one can read about a new road-going disc brake technology leap. It is clear they work, the know-how is there, and they are a need waiting to met by road riders world-wide. When viable disc systems can meet, or slightly exceed, weights of equivalent rim brake systems, well, the proverbial writing is on the wall.
And now for the really good part. Not only will safety be improved by stepping into the modern era, but so will the issues of “Exploding” carbon clinchers and unreliable braking be solved forever. However, safety rarely trumps economics. Don’t think so? I have spent a fare share of my career in aviation, and the only way an improvement became adopted was through some sort of tragedy. This is not to foolishly claim wheel manufacturers are evil, diabolical murderers. It is just they have so much money and time invested in rim brake research, which disc brake technology will completely wipe out. So, do not expect wheel manufacturers to go oh-so boldly into thy disc-laden good night.
To add a bit of relevance, I have been riding motorcycles for over thirty-two years. A few of those years were spent racing, thus I have a pretty go handle on the dynamics of braking (more on this in a bit). Meanwhile, on my road bike on long descents, I have noticed I often end up alone out front rather quickly. Upon polling fellow ride participants, and evaluating my own riding, I have discovered a few interesting things. One, most people are terrified of descents, compounded with a definite fear of the front brake. This, in turn, leads to a near constant application of both brakes, which is very hard on wheels, especially carbon clinchers. And finally, some old habits are hard to break (no pun intended). I tend to use the brakes on my bike the same as I do on a motorcycle – The less braking the better, and when I do need to brake, it is a last second, hard, modulated application to set my corner entrance speed. And contrary to popular belief - You can indeed brake all the way to the corners’ apex.
I believe the rim brake had long ago reached its potential, and the disc will offer a lot more than the obvious superior braking power. And, the debate over weight and complexity will eventually sort itself out. Clever folks are already adapting new technologies and will apply it to yield light, powerful braking systems, allowing at long last, wheels with lighter rims, negating the heat and poor braking issues with carbon.
In regards to application engineering, radially mounting the calipers will yield exceptional strength and balanced braking forces, plus more even pad wear. Of course, forks and chain/seat stays will all have to be beefed up as the additional forces in these areas will have to be dealt with. The weight and balance of the bike and braking forces will all become homogenous with the benefits of centralized mass, and improvement in the moment of inertia. In plain English, these are all good things.
I used to think the people most resistant to change were pilots and novice computer users. Well, if cyclists are indeed resistant to change to disc brakes as the article suggests (and my informal rider polling indicates), they will indeed be left behind.
Especially going down hills.