A Brief Visit to Discworld
Among the bikes I test rode a while back was the Volagi Liscio, which despite having a cool name wound up being very disappointing. But the main thing that differentiated it from the other bikes I’ve looked at is that it had disc brakes.
Disc brakes have been standard on mountain bikes for a while, but the technology never made the leap to speed-oriented road bikes. One obvious reason for that was a big weight penalty. However, several manufacturers have come out with new versions that could conceivably work on a road bike without weighing it down to a crawl.
In fact, some industry pundits have proclaimed that it’s only a question of time before disc brakes completely replace rim caliper brakes as standard equipment on all road bikes. For advantages, they claim that disc brakes offer better performance in wet conditions, and modulate better-that is, they aren’t as suddenly “grabby”-as rim brakes.
For those reasons, I was anxious to test ride a road bike equipped with disc brakes. What I experienced caused me to swear off disc brakes forever.
Now, I can’t attest to wet-weather performance, since I didn’t ride in the rain. Whatever! It’s not an issue for me, because I try to avoid riding in the rain… especially on my primary road bike!
As far as weight goes, it’s difficult to judge. The Liscio was heavier and more sluggish than other bikes I’ve tested, but I couldn’t pinpoint whether that was due to the extra weight of the brakes or in combination with other factors. Certainly, though, there’s some penalty for that excess weight.
As far as modulation goes, I’d put it like this. If I were to rate stopping power in terms of percentage points, rim brakes have about four settings: 40% stop, 65% stop, 90% stop, and emergency over-the-bars 100% stop. Not a lot of modulation between settings, but great stopping power.
I didn’t really notice much more modulation in the disc brakes. After all, how many different levels of braking power can you perceive? But the kicker was that after all that talk of “better performance”, when I grabbed the brake in an emergency stop, the disc brake simply couldn’t stop the bike. In terms of percentages, it felt to me like the disc brakes offered the following levels: 20% stop, 30%, 40%, 50%, 60%. And that’s where it topped out: at their best, disc brakes only offered 60% of the stopping power of regular rim brakes.
So the choice here seems to be this: you can have lightweight brakes that work great everywhere except in the rain, or you can lug around heavy brakes that are very predictably only 60% effective in all conditions. That doesn’t sound like a formula for universal acceptance to me!
So disc brakes get two thumbs down from this rider. Cycling is dangerous enough as it is, and I can’t imagine why anyone would buy a road bike with brakes that don’t work.