Road discs – an alternate view

I like disc brakes.

I NEVER liked rim brakes.


So when I heard that road bikes were finally stepping into the modern age and slowly adopting discs, I did a little jig; only a little one but one none the less. If there’s one thing that being so heavily into mountain bikes for so long taught me, was that disc brakes, without question, are superior in every way to a rim brake.

Now don’t get me wrong here, I’m not some mountain bike infidel preaching his brand of dirt (get it? that was a pun!) to the road bike world. I spent many, many years on a road bike and these days I spend almost all my ride time on the black top. When I departed with my last road bike, I’d gone through several sets of road brakes on that one bike alone (in an aim to find something that was… good), so I am fairly well acquainted with the whole rim brake thing (not to mention the years of rim brakes on my mountain bikes).

Back in ’96 or so, I remember quite clearly many a mountain biker squealing the same thing that I now hear from the road bike fraternity; I even remember a shop wrench claiming disc brakes were a fad and would never catch on. Now, almost twenty years on (shit, has it been THAT long??!), the arguments we are hearing are so similar in fact, that it’s all quite humorous. Yet I don’t see rim brakes on ‘serious’ mountain bikes any more… or even cheap ones for that matter.

But why do I think it’s a good thing to have discs on a road bike? Simply, it’s control, not power; there is a massive misunderstanding in regards to what disc brakes are about.

A road bike needs eyeball popping stopping power about as much as my head needs a(nother) hole in it – let’s be honest, any disc will have more stopping power than the pathetic contact patch of a road tyre could ever hope to hold on to (which is why the traditional calliper brake has reigned supreme for so long). No, it’s not about the ability to stop on the dotted line but all about the ability to slow down to a stop quickly and in control before you pass it.

Rim brakes do this!!

I proffer that they don’t. Sure they will pull you up but not with the same effect, because in no way can they mechanically deliver the same amount of controllable power. Further to this, with rim brakes you are severely limited by the actual braking pad compound (you know, the important bit that does the grippy bit), after all, who wants a sintered pad chomping into their expensive rims, ultimately damaging their wheel sets? And let’s not even go near the discussion of braking compounds on carbon rims…

The idea of the rim being a giant disc is a nice theory but given that that disc is also your rim, which incidentally you want to be as light as possible, and you can see the issues. Rubber pads are nice and all, until it gets wet, or they heat up, or the rim goes a bit skewif, but really, it’s making do with second, or tenth best. Oh, and let’s not mention that loosing rim brakes will actually make rims lighter as you no longer need the braking surface – and remember, it’s all about rotational weight…

Good disc brakes allow a rider to deliver a lot of power, easily, yet not lock the wheel up (which equates to loosing control). This is referred to modulation and a well designed system will have oodles of modulation, which in turn allows a rider to slow down quickly AND in control. When you consider the compromised brake control/power input afforded by riding on the hoods (that’s a really balmy way to pull a lever when you think about it), you would think people would welcome the additional power. Further, and almost perversely, with a larger disc rotor you can gain more stopping power but more importantly, more modulation; a comment (re. road brakes) I once read where someone said that they could see no point in a rotor any larger than 140mm (!), clearly demonstrates some of the misunderstanding going on right now.

But, and regardless to what everyone thinks or not, the simple fact that discs are now showing up on road bikes and as Rich pointed out, on some production models are the only option, signifies the beginning of the end. If the UCI turns around and says all good on discs (that they have not is really the only reason rim brakes are still around), then that’s the final nail. As the mountain bike world saw, someone, somewhere, thought up a great new way to force everyone into updating perfectly good kit – a pointless new wheels size called 27.5”; and that was that, 26” is now dead. I feel the same will happen here. Discs will initially be seen as a premium choice but before long will probably the only choice for consumers the world over when it comes to the stopping options for road bikes.

Unlike the 27.5” MTB wheel, discs for road bikes I see as actually being a good thing.