I’m currently riding a carbon fiber road bike equipped with a mechanical drivetrain and hydraulic disc brakes. It wasn’t that many years ago that I wrote how I didn’t see how or even why disc brakes would make their way onto production road bikes, or even custom road bikes for that matter.
My concerns were voluminous. From a piece I wrote in 2013 I outlined the following problems:
- If you boil your brake fluid on a descent, your brakes can fail.
- Generally, you want the bike to offer some vertical flex at the dropouts; disc brakes would demand beefing up the fork and stays.
- Many mountain bike disc brake system offer poor modulation. Road bike brakes need to offer great modulation.
- Pad retraction is an issue on many mountain bike brake systems. Roadies won’t put up with rubbing brakes.
- Disc brakes won’t improve a bike’s aerodynamics.
- The hydraulic lines will require working hand-in-glove with manufacturers to offer suitable frames.
- There isn’t enough room in control levers to add a master cylinder.
- It’ll make the bike heavier. Roadies are allergic to heavier.
Each of those was an understandable concern. However, when I spoke to Brent Graves, who was then the product manager for Specialized’s road bike line at the time, he dismissed every concern I brought forward as just “an engineering problem.” His was the sort of confidence that allowed man to go to the moon. Every time I listed an issue, he’d repeat, “just an engineering issue.” In other words, ‘we will figure this out.’ NASA engineers decided how big the computer in the command module could be before they had the computer built for the rocket. It’s like saying, “I need a car, but it needs to seat six and get 100 mpg.”
I bumped into Graves this past week at Sea Otter. These days he is President and CEO of Cane Creek. Our conversation didn’t even bother with disc brakes. Why? Simple. That summer day back in 2012 he predicted that we’d be seeing the first production disc bikes by 2015 and by 2018 disc brakes would be available on bikes at a wide array of price points and groups. As it turns out, he’s better than the lady with the neon sign and the crystal ball.
All the proof we need is that you can find Tiagra hydraulic-disc-equipped road bikes at the $1000 price point. I’m not even sure Graves would have predicted that.
Now Graves had me at a disadvantage. In the summer of 2012, he already knew what was coming out in 2013. He had already planned what was to come out in 2014 and was working on the 2015 model year of bikes. It wasn’t impossible for him to extrapolate out from there, but still, a lot had to happen in three years, and on schedule.
I can’t say I didn’t believe him, but I knew I was going to need to see it to believe it. And now I’ve seen it.
But just what have I seen? First, I’ve never experienced hydraulic fluid boiling on a descent and brakes fading. The bikes I have ridden and reviewed don’t feel unusually stiff; they still feel like normal road bikes. I seriously doubted that ride quality would remain consistent. Modulation is off the charts, better than regular rim brakes. Some aerodynamic tests say that a bike’s aerodynamics decrease with the addition of disc brakes, but others say that disc brakes improve them; let’s call it a wash. As it turns out, manufacturers have been only too happy to route hydraulic lines internally. It makes assembling bikes hell, but it really cleans up the appearance of the bike. And my problem with no space for the master cylinder? Well, levers have gotten bigger, but not so much bigger that they are difficult to hold. SRAM even redesigned the shape of their first lever to make it more ergonomic.
The only points on which my concerns remain at issue are rotor rub and weight. Centering the rotor in the brake caliper isn’t hard to do with good lighting, but tolerances are so tight, the caliper needs to be moved each time a wheel is changed. Not dynamite, especially for pro racing. But what about weight?
So far every rider I’ve met who has ridden disc brakes has liked them. Also true is that every rider I’ve spoken to who has ridden disc brakes is willing to give up a pound or so to get such a staggering improvement in brake performance.
There’s another point I hadn’t considered when I was naysaying discs. I was concerned about the limits of adhesion of 700C x 23mm road tires pumped up to 100 psi. I mean, it is possible to skid a bike with those tires if you put a death grip on the levers. But what about when you’re running 28mm tires pumped up to 75 psi? I can say from personal experience that it’s a lot harder to break those tires free. Increase that contact patch to 40mm wide and you can brake hard—even on dirt.
Back to that bike I’ve been riding. When I enter a turn I brake significantly later than I used to and I don’t fear breaking the tires free and skidding (and losing control). The improvement in modulation gives me control I couldn’t imagine with rim brakes. The weight? I’ll take control over a lighter bike any day.
I own three bikes with rim brakes and I don’t plan to sell any of them any time soon (well, maybe one of them). They are great bikes all the way around. But disc brakes are absolutely better and certainly here to stay. Direct-mount brakes are arguably the dying gasp of rim calipers, though they are a pretty good gasp.
I’m not going to suggest that anyone who is pleased with their bike (or bikes) needs to buy a new bike. I am, however, impressed with Brent Graves’ vision. He was a proxy for a great many product managers and engineers in the bike industry. They believed that disc brakes would make for a notable improvement in road bike performance and they’d be able to offer it at price points attractive to almost any rider. They were right.
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