Disc Brakes for Road?

Since UCI’s recent announcement that it will permit riders to utilize disc brakes on road bikes in UCI-licensed events next year, there has been much ink spilled worrying about this issue.  Hyperbole has ranged from “pros sure to cut off limbs via razor sharp disc rotors” to “all of your non-disc bikes are now worthless in the resale market.”  On that first point, I haven’t seen too many serious disc brake related injuries in cyclocross races (where there is a significant amount of rider to rider contact and crashing).  On that second point, if you’re buying bikes based on resale value, then perhaps your values are off.

The real pros and cons of disc brakes are pretty self-evident.

Pro:  Greater stopping power and greater modulation than rim brakes.

Pro:  Greater braking power in wet/inclement conditions.

Pro:  Easier to dissipate heat in a safe fashion on mountain descents, as compared to rim brakes.

Pro:  More consistent braking force in all conditions.

Cons:  Wheel removal/installation becomes more challenging or time consuming because of rotor alignment (and in particular, when thru axles are involved).

Cons:  Greater weight.

Cons:  Greater aerodynamic drag.

Cons:  When not properly aligned, greater propensity for brake drag / mechanical drag.

Cons:  More technically challenging setup.

Honestly, a lot of the pros and cons are situation specific.  I’m never really in a circumstance where cutting a second off of a wheel swap will impact my life, so the wheel installation/removal is a non-issue; that’s the case for many riders.

I’m typically pretty pro-technology.  The last time I posted on this topic, almost four years ago, I was rabidly pro-disc brake.  For gravel, touring, and many other purposes, I am still very pro-disc.  The reason that I am pro-disc in those venues is because I believe disc brakes are well suited for those types of riding.  So are disc brakes well suited for road riding?  Sure.  For some.

I ride here in flatlandia.  I’ve never had a descent on a road bike where I’ve had a concern about stopping power or brake overheating.  Even when it rains, a minor adjustment in technique (squeeze the brakes a bit early to dry the brake track; modulate pressure more carefully) works well.  For me, the penalty in weight and drag outweighs the benefits of disc brakes on road settings.  When we’re doing a fast group ride, the 10-15 watt drag penalty of disc brakes at road speeds is palpable and not appreciated.  I’ll take every advantage I can (legitimately) get in those rides.  As a relatively light rider who runs quality wheels and well-maintained rim brakes, I run out of tire traction long before I run out of stopping power.

So for me, riding here, disc brakes for road don’t change my life.  And when the weather gets really bad, I shift over to the Moots and ride it instead…with disc brakes and 35c tires.

If I was riding in Colorado on a regular basis, I’d be agog about going to disc brakes.  They make perfect sense in mountainous conditions.  Right gear for the terrain.

I have a good friend who has switched to road disc, and he loves it–even in Illinois.  More power to him.

In the pro-cycling realm, I think it’s unlikely that every bike will suddenly become disc brake.  We’re not going to see TT bikes with disc brakes any time soon; the drag penalty doesn’t make sense.  In flat stages, running disc brakes likely won’t make sense.  In the mountains, disc brakes give riders a performance edge–and more importantly, they give riders a safety edge.  Better, more predictable stopping in all conditions–that’s what they bring.  To me, it makes perfect sense for UCI to allow pros to use disc brakes…because it makes the riding safer in mountain stages.

I suspect that the real effect in pro races will just be even greater specialization of bikes.  Just as some riders have switched mid-ride between a TT bike and a ‘climbing’ bike in mountain TT stages, we will see riders bringing a TT bike, a disc-brake bike for mountains, and a rim-brake bike for flatter road stages.  Does that mean rim brake bikes are suddenly worthless, or that every rider is going to go out and have to buy a new bike?  Nope.

It means that pros will have a better-suited tool for one aspect of their racing…and that technology will trickle down to other riders for whom it makes sense.  Will my next road bike be disc or rim brake?  I don’t know…I don’t have plans to replace the Madone any time soon.  When I do go to replace it, I’ll look at the available options and pick what makes the most sense for my riding, as I’ve done in the past.  By then, I suspect there will be lower drag disc options…and maybe those will make the benefits of disc brakes win me over.

What I perpetually don’t understand is why so many in cycling are so anti-progress.  I can understand that shops don’t want to have to stock forty different bottom bracket variations–completely get it.  But when there is some “new technology” (to the extent that road disc is new) that enhances safety for a significant group of riders, why be so pessimistic?  The sky is not falling.  Road disc for those whom it benefits.  Rim brakes will be around for others, for a very long time.


5 thoughts on “Disc Brakes for Road?

  1. I’m all for disc brakes. I don’t race so I don’t really care about the extra few seconds it takes to thread a thru-axle. Also the extra drag that is produced is irrelevant to me. I live in rainy Portland, OR so in the wet discs are great. There isn’t a delay between slowing down and squeezing the levers.
    Why are cyclists so adverse to change? I’m relatively new to cycling (only been doing it for the last 3 years). Was there this much debate when quill stems went away, or when full suspension became a thing? Those are just the first big changes that came to mind that I can see people getting irate over. I remember when 29’ers becoming a real thing a few years ago and the anger and debate and just our-right refusal to change to something new was amazing to see. I used to be really into cars and for the most part (excluding the hot rod guys who wish cars never left the ’60s) people welcome change, even look forward to what new technology the car companies will come out with in the next model year. But in the cycling world it seems for a lot of people its the opposite. People think every change is because some marketing department says things need to change (guess what people, that happens in every industry) and seem to forget that some changes are because engineers figured out how to get something to work better.
    Anyways sorry for the long paragraph but I largely agree with you about discs. They’re great and I look forward to engineers making them better over the years.

  2. From the shop perspective, there needs to be a standard… too often companies, take Campagnolo for example, like to do their own thing while I can use a SRAM chain on a 105 drivetrain. Also, I can see thru axles on a cross bike but I think that’s unnecessary for the road.

    Just my two cents.

  3. We spoke about this a few days ago at work (nothing bike related, just many people riding). What came out of it, for us, the UCI needs to make them mandatory on certain stages. Not to be the big evil corp, but if half the riders start braking on their rim brakes and the other half zip by because their braking point is another 100m down the road there will be carnage.

  4. One thing to consider is that many pro bikes are adding weight to get the UCI limit – so the heavier argument won’t affect them as they will still be on the limit. In the mountains expect the road pro’s to really start racing the downhills as well as the uphills. And when it rains there won’t be neutralised descents – good for fans

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