By Jim Langley

One of my goals at Interbike was looking at the current state of disc brakes because, as we’ve reported, they’re showing up far and wide on road bikes -- even now being allowed in the pro peloton should a team choose to spec them.

Here’s a little news about discs, some related products and a few thoughts on the current pros and cons.

Massive recall related to disc brakes

Let’s start with the biggest news, which is related to an issue we covered back in the spring, when Trek recalled about a million bikes in order to replace defective quick-releases. The issue was that the QR’s levers opened past 180 degrees, which allowed them to get stuck in a disc brake rotor. This can lock a wheel, stop the bike and possibly cause an accident and injury. [Editorial comment: yes, you would have to be pretty unaware to actually ride your bicycle with the wheels not tightened.]

This week, months after that recall, the industry organization the Bicycle Product Suppliers Association, in cooperation with the Consumer Product Safety Commission, Health Canada and Profeco, the Mexican consumer protection federal agency, along with 13 bike companies representing 17 well-known brands, issued another and even more extensive recall about the same QR/disc-brake issue.

According to the recall, these defective QRs were used on bicycles purchased as far back as 1998, and they estimate that up to 1.5 million more bikes may be at risk. To determine whether your bike(s) are affected, watch the BPSA’s excellent video. It walks you through the issue and gives you a simple test to determine if you need to put in for replacement QRs. You’ll find it here: http://quickreleaserecall.com/

Shimano’s Flat Mount Standard

In more-positive road bike disc brake news, Shimano announced a new Flat Mount disc caliper standard last year, but it took a while for it to be rolled out. It was on lots of 2016 bikes in Las Vegas and has now even been adopted by SRAM.

ShimanoFlatMountDisc.WEBWhile a few road-going bikes had discs decades ago, modern road discs trickled down from the ones on mountain bikes where strength, durability and easy maintenance and replacement often trump beauty, refinement and integration, the hallmarks of fine road bikes.

What the Flat Mount standard does is place the calipers right next to the frame with flush bolts for a very tidy low-profile look while also increasing stability and power from the caliper for optimum braking.

Adds Shimano, “The new Flat Mount front fork and rear stay fitting (BR-RS805 and BR-RS505) also brings aerodynamic advantages by introducing a closer fit between the caliper and the frame, reducing the need for visible mounting bolts. This new design allows consumers to move away from the mountain bike history and look, which has been used until now, using a method better suited to high performance road bike riding.”

It’s one of those things you have to see to appreciate. To me it’s another nice step toward integration and making discs fit better onto road bikes.

Internal housing routing makes for super clean setups

Shimano’s Flat Mount standard also lets the housing run down the inside of the calipers, which helps keep your road bike clean and aero. Even more impressive, a lot of companies now are running the hydraulic lines inside the fork and frame so they’re almost invisible.

These are nice developments. Disc brakes already cleaned up the fork crown and seatstay bridge area on the road bike by doing away with the sidepull brake calipers. Now that the hydraulic lines can be hidden out of view and the disc calipers can almost be part of the stay and fork, there’s less and less distracting from your road rocket’s clean lines.

Park Tool’s new disc mount mill ensures perfect caliper alignment

While it’s intended as a professional tool for bicycle shops to use, I was highly impressed by Park’s new Disc Brake Mount Facing Tool Set at their booth at Interbike.

This ingenious milling tool clamps into place between the dropouts on all types of forks and frames. Once in place, the tool’s cutter is perfectly aligned with the disc brake mounts, allowing the mechanic to machine the faces of the mounts to be exactly adjacent to the disc-brake rotors attached to the wheels.

This ensures that the disc-brake caliper will mount to the fork/frame in the perfect relationship to the rotor for maximum braking power and to prevent misalignment and/or rubbing. This is first tool I’ve seen that can guarantee that the rotors and calipers are perfectly placed.

Watch Park’s video to see it in action. Then, if you have a bicycle with disc brakes, find a shop with this new tool and ask them to give your bike the treatment and I bet you’ll experience better braking than ever. 

Pros and cons of road disc brakes

Let’s wrap up with some final thoughts on the current pros and cons of the latest disc brakes for road bikes. Mechanical and hydraulic discs are getting better and better. If you want superior all-weather or all-terrain braking on a road bike, properly adjusted discs are the new standard.

Assuming you get quality brakes properly adjusted, they require less maintenance than rim brakes, they can’t wear the rims like rim brakes can, and they provide excellent speed control and stopping power for all types of riding. Because with discs rims don’t require braking tracks, they can be made lighter, saving some of the weight that discs add to road bikes. Keep in mind that you feel rotating weight the most, so removing it at the rim is something you will notice.

For cons, because the frame and fork need to be strengthened to withstand the force from disc braking, there is still a weight penalty for going to discs. So we may at some point see a 10.5-pound Fuji with disc brakes at some future Interbike (like this year’s ultra-light model with rim stoppers). But, that same bike will be even lighter still with rim brakes.

And things like the trend for through axles instead of quick releases -- while it prevents recalls, such as the one I started this article out with -- only add more weight. So for now, you can still make the case for the classic sidepull rim brake if you want the ultimate road riding experience. However, if you’re a gravel-grinder, an adventurer, a globe trotter packed for life on two wheels, etc., you will certainly appreciate the advantages of modern discs.


Jim Langley is RBR's Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He's the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his "cycling aficionado" website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim's streak of consecutive cycling days has reached more than 8,000. Click to read Jim's full bio.

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