The Crucible: Tarmac vs. Roubaix

The final switchbacks of Malibu’s Decker Canyon Road

After months of riding on both the Roubaix and the Tarmac SL I was dismayed. I had yet to determine a preference relative to my own riding and that was killing me. Mind you, I wasn’t trying to determine the better bike, because I didn’t actually think one was superior to the other, but I believed that because the two bikes were different I must, as some point, arrive at a conclusion about which better suited my taste. Simply put, I should get down a technical descent on one faster than the other. Which would it be?

Malibu contains more than a dozen roads that run from the ridgeline of the Santa Monica Mountains down to Pacific Coast Highway. The roads can drop nearly 2500 vertical feet at grades of up to 18 percent. The descents generally range between 4.6 and 9.2 miles. Most of them feature more than a dozen turns per mile. At 40 mph, that’s a turn about every six seconds … and many of the turns can last for three or four seconds.

Of these descents, three offer grades steep enough to sustain speeds above 45 mph over road surfaces that don’t make the experience seem like fodder for an episode of Jackass.

Kanan Dume Road recalls the sweeping turns and consistent grades of the Rocky Mountains. It features far fewer turns than the other descents and a good deal more traffic.

Tuna Canyon Road is where the ill-fated Red Bull Road Rage was held. It features more than 70 turns in 4.2 miles and drops some 1800 feet at an average gradient of 8.1 percent. On the descent’s one significant straight (which was used for the speed trap in the Red Bull event), it is possible to clock 60 mph just before a sharp left turn will cause you to rethink your actions or alter your future. I know plenty of riders afraid to descend this road and it’s one of a handful of roads I descend where I’m unwilling to let the bike run. The looming wall of dirt has whispered things to me about deceleration trauma that I’m unable to repeat.

Decker Canyon Road is a bit like Tuna Canyon light. It is almost a half mile longer, drops 150 fewer feet, culminating in a 6.8 percent average gradient, as compared to Tuna Canyon’s deceptive 8.1 percent average. It also features nearly roughly ten fewer turns, meaning the road bends don’t come quite so frequently.

Decker Canyon is my road of choice for challenging myself on a descent or when testing the limits of a bike’s cornering. The descent is fairly steep, but not super-steep, the turns come in rapid succession and nerves of steel are tested in the turns, not in the chutzpah of straight-line speed.

I came up with a crucible. I’d take both bikes up to Malibu. I would ascend Encinal Canyon Road six times—three times on the Tarmac and three times on the Roubaix—and following each five mile, 6.3 percent average gradient ascent of Encinal Canyon I would plummet down Decker Canyon.

My first two ascents of Encinal were aboard the Tarmac. The second two were aboard the Roubaix. Trip number five was back on the Tarmac and the final trip was made aboard the Roubaix. The six circuits only added up to 57 miles, but the climbing totaled more than 9000 feet ascended.

My position was very similar on both bikes; saddle height and setback was the same and reach to the bar was within a centimeter, though the bar on the Roubaix was almost a centimeter higher. Switching between the two was unremarkable from a position standpoint. However, as soon as I did switch from the Tarmac to the Roubaix the increased vibration damping was immediately apparent.

According to my GPS data my fourth and fifth ascents (Roubaix and Tarmac, respectively) were my two fastest; my average speeds were within a tenth of a mile per hour of each other. Interestingly, I burned fewer calories on the Roubaix, lending further credence to the idea that cutting vibration can decrease fatigue.

My three fastest descents were aboard the Tarmac. On those descents (first, second and fifth) my max speed was 46, 46 and 46.5 mph, respectively. My slowest descent, surprisingly, was my first trip down on the Roubaix.

The tightest turns on the descent, the ones on which there was no question of braking, just how hard would be necessary, were all right-handers except for the final switchback less than a mile from the bottom. I was able to carve very consistent lines through these turns and found myself consistently shaving the yellow lines on the Roubaix and six inches to the right on the Tarmac. That minute difference made a big difference at speed.

What I noticed was that the more I felt like I was really having to manage the bike—push it—to negotiate a turn, the more inclined I was to brake before the next turn. I did almost no braking during turns on the Tarmac but did scrub speed with some regularity during turns while aboard the Roubaix.

A brief word on my descending: Fast. I like it. Roller coasters were always my favorite at amusement parks when I was a kid but today, compared to mountain roads, they lack a critical interactivity component. That said, I don’t take what I believe to be are risks. While I find the foregone conclusion of a roller coaster lacking, I enter every turn with the belief that my safe exit from it is deal-done. As soon as I feel like I’m really pushing a bike, I back off. My empiricism ends at the point of wondering just how fast I can enter a turn and exit it without a yard sale. Aided by downhill pads and a Kevlar suit I might play my hand differently and bluff my way straight to call, but in Lycra I do little more than ante up.

What I learned was I preferred the Tarmac for descending. I’m unafraid to declare my surprise at this. I really thought that the Roubaix would see me brake less and roll up to higher speeds, but it just didn’t happen that way and I can say that I did my best to make each of those drops an E-ticket ride.

But how many people buy a bike for how it descends?

In my estimation, more bikes ought to be purchased that way. I think it indicates a great deal about a bike’s character. A downhill turn is the ultimate litmus paper for any bike. If the bike won’t turn, you should ask yourself what that bike is meant to do and what you plan to use it for.

But here’s the asterisk: My preference for the Tarmac was revealed under fairly extreme circumstances. Most riders won’t ever ride down a road as challenging as Decker. There just aren’t that many of them in the world and unless such a road is part of one’s regular vocabulary of roads, the reasonable response is to back off. So what about the downhills more regularly encountered? What if, say, you rode in the Rockies or the Alps?

If I factor Malibu out of the equation and consider the other roads I took the bikes over, the many other roads I’ve ridden around the world, the answer is easy.

The Roubaix is easily one of the best all-around bikes I’ve ever ridden. I’ll venture to say it is one of the best thought-out bikes on the market. For most riders under most circumstances the Roubaix is an easy correct answer. It’s lighter than elfin armor, handles with the relaxed control of a Bond villain and cuts vibration like a power outage.

The Roubaix should be the default answer for anyone considering a Specialized road bike (or perhaps many other road bikes).

So where does that leave the Tarmac? It is, without marginalizing it, a bike for the margins. The Tarmac is the Navy SEAL to the Roubaix’s sailor, the surgical scalpel to the butcher knife, the truing stand to the Y Allen wrench. It is the accept-no-substitute for criterium racing, intestinal descents and the most aggressive group rides.

They are both spectacular bikes and well-enough differentiated to have earned their place in the Specialized product line.