Bend in the Road: Discs are almost there

Why I’m 90-percent sold on road disc brakes

After putting in a few hundred miles on a handful of different road disc bikes, I’ve gone from ‘eh’, to ‘meh’, to ‘okay, yeah’. But Shimano or SRAM need to tick two more boxes to make me a full convert.

One, I want be able to adjust how my brakes feel. More specifically, I want to be able to dial in the free-stroke adjust, so the brakes engage just where I want them to as I squeeze the levers.

And two, I don’t want disc brakes to squeal like wounded hyenas under heavy braking.

Both Shimano and SRAM have decent explanations about both of these things, and we’ll get into that a bit below. But as a rider, frankly, I don’t care; I just want it to work the way I want it to work.

Dialed-in feel

If you got on my bike, it would feel a little funny to you, just as your bike would feel strange to me. Neither is wrong, they are just set up to our sizing and preferences. With rim brakes, we can easily adjust how the brakes feel with a simple twist of a barrel adjuster or a tweak of the quick release. With disc brakes, the situation is the same as the brakes on your car; it is what it is.

Now, with my car, I have never thought once about adjusting the where the pedal engages as I press it down. But my car isn’t my bike. I want that sucker to feel perfect, with the brakes engaging just where I want them to, whether I’m bombing into a tight corner or just toodling around town.

SRAM does not have free-stroke adjust on its Hydro R levers. Shimano technically has 1cm of free-stroke adjust, but honestly I can’t feel a substantial difference, and this adjustment is there primarily to balance out the feel left to right, and compensate for the longer hydraulic hose of the back brake.

Road disc rotors are powerful and dependable. They can also be noisy

SRAM does, however, have free-stroke adjust on its new Guide mountain bike brakes.

“People who want it to feel really heavy, can dial up pad-contact adjust to get that quick engagement, and those who like a little more play can get that,” said Nate Newton, SRAM’s road technical rep. “The thing is, most people would never ever adjust that. There definitely is a subset who want that adjustability. But what I have found doing demos is that most people will jump on a bike and just ride it. If I ask people how they like their brakes to be set up, they usually have opinions. But it doesn’t seem to come up unless I push the issue.”

Silence!

In my experience, road discs are quiet most of the time if set up properly. But I want them to be quiet all of the time. Simple as that.

Riding here in Boulder, Colorado, there is one section of road where I can usually get rotors to howl with heat build-up, and that’s coming down Sunshine Canyon, a nine-mile stretch of road that averages about eight percent but tilts to 23 percent, with some sharp switchbacks that require hard braking over about 3,220ft (980m) of elevation change. I weigh about 185lb (84kg), and going from 50mph to 20mph a few times in quick secession does the trick to get the rotors chirping. Outside of that, though, I haven’t had any problems.

This weekend the Rapha Gentlemen’s Race in Colorado provided an excellent test course for disc brakes, with 13,000ft of descending over 107 miles, some of it on loose dirt, and some of it on steep pavement. The only spot I was able to get Shimano R785 140mm rotors to howl was that same spot on Sunshine.

For Shimano, pairing the appropriate braking technology with the bike and rider is everything, said company spokesman and former ProTour mechanic Nick Legan.

“Braking is always a function of traction. Good descenders do late, hard braking, biasing the front brake, then backing off into the corner. But you have to pair braking power with the traction you have,” Legan said, adding that a heavy downhill bike with substantial rubber and full suspension can keep traction more easily than a light road bike with skinny tires.

Going to a bigger rotor (160mm) up front, and perhaps in the back as well, would likely eliminate the heat-induced squeal, Legan said.

This could indeed be a fix, but I want to brake companies and bike companies to sort this out, not me. Perhaps bikes 56cm and larger get the 160mm front rotor, and 54cm and smaller go 140mm?

Another smaller noise issue — the levers rattling over rough roads when not grasped — was fixed with a solution courtesy of our US tech editor, James Huang. Since hydraulic brakes don’t have cable tension pulling the levers taut, both Shimano and SRAM levers can rattle. On smooth pavement there is no problem. On rough roads, if you keep your fingers touching the levers, there is no problem. On rough roads when you ride with your hands loosely on the tops, however, there is a definite rattle. James showed me how to put a piece of padded tape inside the lever; problem solved. But again, this should be solved at the manufacturer level, not the rider/tinkerer level.

A little rubber bumper on the silver, cylindrical bumper addressed the lever rattle

When it comes to disc road brakes, Shimano and SRAM certainly aren’t, um, stopping. Expect to see more and more of the things — and hopefully, more and more improved versions of the things — as we roll into the near future.

“There is a reason that every wheeled sport has gone to disc brakes,” Legan said. “They’re better than rim brakes, period.”

Perhaps. But I want a quiet, customizable experience before I go all in.

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