Wind Tunnel Test: Disc brakes versus rim brakes

Can the new road bike braking standard cheat the wind?

Brakes Disc Parts
Wind Tunnel Test

Testing was done at Specialized’s in-house facility in Morgan Hill, California.

Granted, Specialized has more than a little skin in the game when it comes to making the “disc brakes for road bikes” argument. Four of California bike maker’s most popular models — the Tarmac, Roubaix, Diverge and Crux cyclocross bike — have at least one disc brake option. But even if the Big Red S is a little biased, this wind tunnel test is worth a look. In the video below, Specialized goes inside its in-house facility to find out how much slower a disc brake equipped Tarmac road bike is compared to a Tarmac with a traditional rim brake set-up. And while we can’t sign off on their findings with absolute certainty, we’ve spent enough time riding road and ’cross bikes with disc brakes to say without hesitation that actual braking performance is superior — especially in wet conditions. So is the trade-off worth it? You be the judge and let us know what you think in the comments section below.

About the author: RoadBikeReview is an online community of cyclists who share a passion for the sport. Visitors of the site regularly purchase gear to upgrade their bikes, share inspiring photos of rides, and keep up to date with the latest industry and technology news. Which products perform best? Where to buy them? Where to ride? How to ride better? Cyclists come to for the answers.

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  • DrSmile says:

    How about the extra weight on rotating mass? The more you use those disk brakes the more energy you’ll expend getting the wheel spinning again.

  • conscience of a conservative says:

    First the bike companies make small changes to the set-up calling it aero and sought to convince us this is a meaningful performance improvement. Now when they seek to sell us disc brake equipped bikes the loss of aerodynamics is minimized.

    Not to totally discount the benefit of disc brakes on road bikes but the marketing can make the head spin.

  • Open Mind says:

    I am surprised that there is a 8 second loss with discs. It doesn’t seem like there is much of a cross-section in the brakes to make that much difference. Plus, the braking performance is so much more superior, especially with carbon wheels in wet conditions. The manufacturers will be able to improve aerodynamics and weight as discs become more popular. Road cyclists are just way too conservative and traditional…!

  • Hype says:

    The whole aero thing is mostly hype, unless you are talking time trials or triathlon anyway. Better performance gained with disc brakes then with an aero frame.

  • marc baskin says:

    What was the weight difference between the two bikes? I am purchasing a new bike and the no one was really sure what the total extra weight might be including brakes and disc wheel.

  • Mark Stewart says:

    Disc brakes. Who are we fooling. Absolutely no need for them on a road bike. We neither generate enough speed or carry enough weight to make them necessary. Plus they are ugly

  • codyish says:

    Mark Stewart – I guess you don’t ride in the rain, or descend that aggressively.

  • OGS says:

    codyfish – how often do you lock up your wheels? I never do that on my descents, and I am pretty aggressive if I may say so myself.

    Are you riding in the rain on carbon wheels? Ride Al rims instead, they work just fine.

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