aerodata

Alpha X Wind Tunnel Testing

The Alpha X has been TriRig's biggest and most ambitious product to date. With it, we've created an entire front-end solution designed to upgrade entry-level bikes into full aerodynamic superbikes. And now we have the data that proves that we've hit that goal. In short, putting the Alpha X onto a $1,500 Cervelo P2 made it just as fast as a Cervelo P5 costing about $5,000 more. That means the Alpha X actually saves you nearly $4,000 in the process.

How can this one component make such a big difference? Handlebars are the single greatest component adding drag to the bike. In some independent tests on road bikes, the road handlebars actually contribute nearly twice the drag of a frame. The right bar can make the difference between "standard" and "super" as far as labels go.

Amazingly, our Alpha-X-equipped P2 actually tested significantly faster than the P5, by a whopping 5-7 Watts. It's undeniable that the Alpha X is an amazing piece of equipment. It represents a marked improvement on our own Alpha Classic, previously the fastest bar we'd tested, and proves that it can truly create superbike performance in entry-level bikes. And remember that the Alpha X ain't a one-trick pony. This aero performance is in addition to its other great features.

In our wind tunnel testing for the Alpha Classic, we kept our goals narrow, simply comparing the Alpha Classic against several other aerobars. This time around, we wanted a slightly broader perspective on what the Alpha X is in comparison to the larger market. Specifically, we wanted to know how a entry level bike equipped with an Alpha X would compare to a top-of-the-line superbike costing many thousands of dollars more. In order to keep our comparison as fair as possible, we picked bikes from the same manufacturer - our superbike is the Cervelo P5, and our entry-level bike is the Cervelo P2. We also did some additional apples-to-apples comparisons much like our earlier Alpha Classic test, keeping the P2 in the tunnel and simply swapping out the bars.

Why did we choose Cervelo bikes for these tests? In part, because the industry as a whole has really validated that Cervelo is making bikes at the very fastest end of the spectrum. Virtually every test we've seen shows the P5 as either the fastest bike on the market, or among the fastest 2-3 bikes. In total that tells us it's the best there is. But more than that, we simply love these bikes. The P5's little brother, the P2, is an amazing entry-level bike that takes most of the great design of the P5 and ports it to a completely standard-interface, low-budget rig. When we reviewed the P2, we called it an absolute home run, and that statement still holds. The P2 basically shows us the current "best practices" for an entry-level bike, bar none. At $2500 complete (probably ~$1500 for the frameset if you can find one), it's a low-budget beast, and the perfect candidate for the Alpha X.

Testing Protocol

Alpha X in the wind tunnel

Using a wind tunnel to get a legitimate comparison between different parts requires a fair and robust protocol. Even more important in my opinion is that when you're using tunnel data to make a claim to the public, you've got to make your protocol public as well. That way, readers can make their own informed decisions about the validity and applicability of your data to their riding. Below is a detailed description of how we conducted our tests.

  • Bike: our main test rig was the Cervelo P2, size 54cm, stripped of its drivetrain (no shifters, no brake levers, no derailleurs, no crank, and no chain). The bike was equipped with Dash wheels and a Dash seatpost combo. Obviously the Dash components are not entry-level parts, and were selected because of their small profile that would not contribute much drag. In wind tunnel testing, we want to remove as much noise as possible, leaving only parts that will give a strong signal as to what is actually contributing drag. We equipped the P2 with TriRig Omega X brakes front and rear, and left housing in place for the rear brake, for an accurate simulation of the parts that would be present in real-life riding.
  • Superbike: For our tests with the P5, we used a 56cm bike (just slightly larger than the 54cm P2). Of course, the pad stack/reach were consistent for both setups. Using the larger frame size allowed us to keep the bars slammed for both bikes, and also put each bike's aerobar in the middle of its adjustment range. The P5's integrated Aduro bar does not allow for independent pad stack adjustment, only macro adjustments via the High-V equipment, or micro adjustments via stem spacers. As an alternative, we could have used a 56cm P2 and set up the Alpha X differently, which may or may not have had an effect on the results. However, I prioritized a mid-range bar adjustment, since that would represent a setup that would allow its rider the ability to adjust their position up OR down. In the end, since the positions were the same, and the bars were in the middle of their adjustment ranges, I'm satisfied that it's a very fair and valid test. Again, I present all the information that went into these decisions so that the reader can draw their own conclusions.
  • Position: Every test was made with the bars set to the same pad stack, pad reach, and where possible, pad stance width. Pad stack was measured at the trough of each pad (where your arm actually sits). Each setup measured within 5mm of the baseline (a stack of 625mm for the low-stack tests, 665 for the high-stack tests). The brake lever bores were plugged with identical hemispherical bar plugs (except on the 3T Ventus, which has a non-removable aero end tip already).
  • Extensions: In order to get the most meaningful results, we wanted to use the same extensions across all bars. We used straight extensions cut to 21.5cm for every bar. That length is slightly shorter than what the average athlete might use in practice, but eliminates any variablity caused by what ordinarily happens in front of this section of bar, namely the athlete's hands. We don't believe the shorter length introduced any bias in the results, especially because that length was maintained across all bars tested. The extensions themselves were of identical make and model (TriRig Gamma), for complete consistency (as Mon Mothma might say, "many Gamma extensions died to bring us this information..."). The ends of every extension were plugged with identical hemispherical bar plugs.
  • Tunnel Shreds: For each wind tunnel sweep (called a "shred"), the wind and wheels spun up to 30mph with the bike at 0 degrees of yaw (pointing directly forward, into the wind). After allowing the wind to settle for approximately 30 seconds, we would take a 15-second sample of drag, averaging the data collected during those 15 seconds. Then the bike was rotated 2.5 degrees in the positive direction, and the testing cycle repeated, all the way out to 17.5 degrees of yaw, in 2.5-degree increments. Unlike in our previous tests, we did not test the negative side, as the parts we're looking at (bars) are all symmetrical. The time saved by eliminating the negative side allowed us to add additional tests without compromising the integrity of the data collected.
  • Data: Like our previous tests with the Alpha Classic, we are going to provide data in a couple ways. In the galleries in this article, you'll see the full extent of our tunnel data, mapped out for you to analyze, pick apart, scrutinize, etc. However, for the sake of clarity and readability, we will also present the data as weighted averages, using two separate weight sets. One set simulates a faster rider and/or slower wind (therefore, lower yaw angles), and the second set simulates a slower rider and/or faster wind (therefore, higher yaw angles). Again, the full dataset is available below, for you to draw your own conclusions from. But for those who don't have a PhD in physics or aerodynamics, we present the weighted averages as an easier way to digest this stuff.

With all that in mind, let's get right to the tests themselves: