Kona Tech: Leanda Cave's Aero Testing

Published October 9, 2013 12:17AM

The start of 2013 went very differently than the previous year for Leanda Cave. To end 2012, she won both the Ironman and 70.3 Ironman world championships in the span of a month. Most impressively, Cave broke super-runner Mirinda Carfrae during the grueling Kona marathon to earn the crown as top female long distance triathlete following Chrissie Wellington’s retirement. Then came a string of uncharacteristically poor performances to start the next year: 10th at Escape From Alcatraz, 6^th at Ironman 70.3 San Juan, 10^th at the Columbia Triathlon and 10^th at Ironman 70.3 St. George. These were decent showings, but not exactly up to the standard of the five-time world champion.

Part of the problem was a partially torn hamstring that Cave suffered after taking an extended break from training in the fall and winter. She resolutely tried to work through the injury, but couldn’t muster the same fitness she had the year before. Her bike fit was another part of her early-season woes. After riding a Pinarello for years, she switched to the Canyon Speedmax CF this off-season but some important details were lost when switching to the new rig. Cave traveled from her springtime base in Arizona to the LA Velodrome with a team of advisors in tow to maximize her position on the Canyon Speedmax CF re-fit using both a Retül motion capture tool and the Alphamantis Track Aero System, a drag measurement system operated by ERO Sports.

It only took a few seconds for Retül’s triathlon fit specialist Ivan O’Gorman to know what has been troubling Cave since switching over to the Canyon—her fit is totally different than when she won Kona just nine months earlier. Cave’s fit never successfully transferred to the new bike. With her bike mounted to a Computrainer, O’Gorman started precisely measuring her fit using the Retül Zin tool. With the numbers entered into the Retul system, O’Gorman compared the fit dimensions with her old position stats. The differences were substantial. Her saddle was set 31mm further back than it was a year earlier; the ISM Podium Cave raced last year had been swapped for another ISM model; her saddle nose was tilted downward; her elbow pads were situated 7mm further forward. “This is all over the place,” said O’Gorman after realizing the scale of the inadvertent changes to her fit. “That’s how I feel,” she confirmed. “All over the place.”

Before starting to reset her fit, Cave went down to the track to measure the aerodynamic characteristics of this baseline position that she had ridden to up to that point. The Alphamantis system uses a complex series of algorithms to calculate an athlete’s aerodynamic traits—CdA, for the technophiles—using inputs of power, speed and the air conditions in the velodrome. Alphamantis is an engineering firm that invented a wind measurement device widely used in the bike industry–the Track Aero System is their next creation. The biggest advantage of this tool compared to a wind tunnel is that the rider moves freely without being secured to a set of struts. But while tunnels can measure drag at any wind angle a rider is likely to experience on the road, the Alphamantis system only measures with a straight-on headwind. Cave’s CdA when riding the position she has raced thus far in 2013 was measured at .2705, equivalent to about 173 watts when riding at 23mph at sea level.

She stepped off the tunnel and her bike was brought back up to the fit studio at the rim overlooking the velodrome. Jim Manton of ERO Sports and Nestor Rodriguez of Studio DNA in Carlsbad, CA were on hand to work with O’Gormon on the fit. An aerodynamically fast position that tests well in the wind won’t lead to a fast bike split alone, the fit must be biomechanically sound as well. Combining bike fit with testing on the track allows the fitters to get close to the ideal combination of comfort and aero performance. They can find the fastest position possible, then make small tweaks until finding one that is equally comfortable without sacrificing too much straight-line speed.

Pushing to the max in the aero direction wasn’t the objective of Cave’s fit and test. “We want it to be comfortable and natural,” said Manton. “We want you more comfortable in the aerobars than out.” That sentiment resonated with Lindley.

O’Gorman had her 2012 fit dimensions on file and he and Rodriguez went to work resetting her Canyon to those specs. The bike’s front end is fabulously clean and integrated, and the range of adjustment on any single frame is moderately limited. They found that the size M frame Cave was riding couldn’t quite reach her old fit and O’Gorman made a note to swap for the S size frame. The bike was set to the best position possible and they went back down to the track to test her position and equipment options.

The first run with the new position and no equipment changes saw a substantial aerodynamic improvement. Cave dropped to .2645 CdA from the original .2705 as a result of the simple fit changes that got her closer to her Kona-winning position from 2012.

The first piece of gear tested was the helmet. Without changing fit, she switched from the Giro Air Attack, a semi-aero option, to the Giro’s time trial helmet, the Selector. Her CdA did in fact decrease from .2645 to .2588, but it just wasn’t comfortable for her. With almost no ventilation and large ear covers, Cave felt as if she was “cooking” inside this helmet. Next up was the Giro Advantage 2. This helmet has been around a long time, but it is still very successful for some athletes. Cave experienced a dramatic drop in CdA in this helmet. She produced a CdA of .2257 in the Advantage 2, a massive drop compared to the Air Attack and the Selector.

With helmet data recorded, hydration setup was the next decision to tackle. Cave tested a litany of hydration and storage combinations using a horizontal front bottle, a vertical front bottle, frame bottles, a rear carrier and a rear storage bag.

Bringing extra bottles or supplies is often a tradeoff between aerodynamic efficiency and logistical needs, but Cave won’t have to decide between bringing more stuff and being faster. She tested best when her bike was equipped with an X-Lab Torpedo horizontal front bottle mount, an X-Lab Delta 200 rear single-bottle mount and an X-Lab storage box on the top tube.

Cave finished the fit and aero test with one clear answer for her race setup and one harder decision to make. The hydration supplies will be on her bike, that was for sure. But she and Lindley would have to decide if the additional cooling from the Air Attack work worth sacrificing the speed of the Advantage 2. Finishing her fit would have to wait until Cave was riding a size S frame.

A month later, Cave went back to work on her position with O’Gorman back in Boulder. She received the smaller frame from Canyon with a 20mm shorter reach dimension in the middle of June. This critical change allowed her to experiment with a more demanding fit that she could gradually adapt to over the summer. “She’s riding more aggressive now than she was in May,” said O’Gorman in September, a few weeks before the 2013 Ironman World Championship. He brought Cave’s elbow pads and extension 20mm narrower and dropped her bars by 15mm. She went to smaller Mavic Helium shoes—1/2-size down—and went back to a 172.5mm crank, her old standard from 2012, from the 175mm version that she rode through early 2013. With three fit appointments from May through August, her flexibility improved along with her position to the point that the bike now feels “absolutely wicked.”

Cave used the equipment data gathered using the Alphamantis Track Aero System to inform her race day setup, but her final choices for Kona equipment were still dictated by feel and comfort. In the end, she opted for the Giro Air Attack instead of the Advantage 2. “It’s just the heat,” she said.