It's practically become the calling card of our Tri and TT fits - a simple adjustment that, for most, brings both improved comfort and a decrease in aerodynamic drag. Get it right, and you'll be more relaxed and faster. Get it wrong, and you'll likely be slower while your shoulders scream at you. I'm talking about angling your forearms up so your wrists are above your elbows while in the aero position, and it's a fit adjustment everyone should try to one extent or another.
Angling of the forearms is nothing new. Plenty have done it in the past, and plenty more do so today. Those who angle their forearms to the extreme are referred to as riding in the "Mantis" position because their hands are very high above their elbows (think Praying Mantis). In the world of professional cycling, both Floyd Landis and Levi Leipheimer made use of this position in time trials before it was declared illegal. In triathlon, the most visible of the extreme "Mantis" riders is TJ Tollakson, who rides the position quite well. Up until late 2013/early 2014, cycling's governing body, the UCI, mandated an athlete's forearms be parallel to the ground while on aero bars, but this rule has since been relaxed and now some angling is allowed. No such restriction exists in the world of triathlon (draft legal excluded), so triathletes are free to angle their forearms as much, or as little, as they please. For the majority of athletes, we've discovered the "full Mantis" position is likely too extreme; however, the results of our many aero fits and testing have shown the overwhelming percentage of athletes benefit from at least some angling and, as stated previously, you can almost always spot an "ERO fit" by the angle of the athlete's forearms.
I first began paying closer attention to forearm angle while working with Luke McKenzie as he prepared for the 2013 Ironman World Championships. During our fit and aero testing, we found an optimal arm angle that was both aerodynamically most efficient and quite comfortable for him. From then on, I began angling the forearms as part of our fit process. It doesn't work for everyone, but for most, it has the same effect it did for Luke = comfort and aero efficiency.
It's the comfort aspect of the forearm angle that's important first and foremost. In the end, if a position adjustment isn't comfortable, it won't work. We've found most athletes prefer to have their forearms angled up in the aero position because it provides a feeling of being "locked in' to their position more and relaxes the shoulders. Since you're now leaning into the pads instead of on top of them, you no longer feel as though you're supporting as much of your upper body weight. In other words, it seems to provide better skeletal support of the upper body. Angling the forearms does draw your torso both forward and down a bit, so typically we add reach when angling the arms.
The drawing down of the upper body by angling the forearms up effectively gives you a lower back angle, which is likely the main reason we see a drop in aerodynamic drag. It also effectively draws your shoulders in a bit, so your frontal area gets even smaller. The less you're presenting to the wind, the more aerodynamically efficient you'll be. This is all the icing on the cake of the arm angle change. Again, comfort first, aero second.
All the aero testing we've conducted with different arm angles, there's certainly no doubt the majority of athletes, the overwhelming majority, in fact, find an aerodynamic savings from an upward tilt to their forearms. Sometimes it's a modest gain; other times, the gains are quite significant...almost unbelievable. I decided to test different forearm angles for myself. Below you'll see the three different arm positions I tried both for comfort and aerodynamics.
Arm Position #1
Pretty typical position here, not quite parallel with the ground, but close. I've been conducting a lot of front hydration testing of late, and kept the aero bars in this position to do so. It's comfortable, and I can ride it without any difficulty.
Arm Position #2
We're looking at about a 15 degree up-turn in the forearms. Again, nothing crazy going on, though you can see how it's dropped my head and shoulders. Remember, angling the forearms brings your upper body forward and down, which can lead to less skeletal support. I tested two different amounts of reach for this position. The first was keeping the identical amount of reach as Position #1. It felt very good, clearly more relaxed and I felt smoother on the track. It also seemed easier to look forward from this position. Next I reached out approx 2cm further on the extensions, which brought me forward on the arm pads without drawing me forward on the saddle. Wow, this was Lazyboy comfortable! I now felt completely relaxed in aero and thought I could ride this position all day. Big smiles with the arms angled up and the additional reach we'd expect to go along with it. Nice.
Arm Position #3
Full Mantis position - both with identical reach as Position #1 and the extended reach from Position #2. I was really looking forward to testing this and, admittedly, wanted to like it (which is not a good thing when trying to remain neutral to the results). On the trainer in the Fit Studio, this position felt pretty good. Better when I reached out further, but both were actually pretty darn comfortable while the bike was held in place. That feeling was short-lived, though, because as soon as I began riding the position, I could tell it wasn't sustainable for me. The first several laps were with the standard amount of reach, and I could hardly wait until they were finished. My shoulders were not happy with me, and the position was clearly not as stable as either of the previous two. A lot more concentration was necessary to keep the bike straight on the track. I continued the test by reaching further out on the aero bars, and quite a bit of the discomfort was relieved. While still not feeling stable, I felt as though I could adapt to this position if I spent enough time riding it. Don't get me wrong, my shoulders were still not happy with me; however, I wondered to myself if perhaps the pain was residual from the first several laps of too little reach. I'll test this further in the future.
My CdA from Position #1 had been tested many times over the past two weeks, and the results were as expected. Good, sustainable position. As stated earlier, as soon as I began riding Position #2, I could immediately tell it was more comfortable and smoother. The results were not surprising at all and, in fact, we see an average 10-15 watt advantage for most athletes:
|Position #2||Watts Saved||Time Saved 40K||Time Saved Ironman|
|Angle up 12 degrees||8.7||42.5 seconds||3.2 minutes|
|Angle up 12 degrees w/more reach||13.0||64.4 seconds||4.8 minutes|
The Mantis position didn't work for me and, as you can see, I gave up all the gains from position #2 and then some. In other words, this was the worst of the three positions. The negative numbers displayed below indicate both watts and time lost from this position.
|Position #3||Watts Saved||Time Saved 40K||Time Saved Ironman|
|Mantis Position||-8.7||-31 seconds||-2.3 minutes|
|Mantis Position w/more reach||-1.9||-9.2 seconds||-.7 minutes|
To interpret the above numbers further. The watts and time lost from the "Mantis" position are compared to my Baseline. If you were to compare them to Position #2, with my arms angled up less, you'd be looking at 14.9 watts lost total with a time loss of 73.6 seconds over 40K and a whopping 5.5 minutes over an Ironman bike course! That's a lot of time.
Here's the deal, though. In a wind tunnel, the "Mantis" position is likely to test very fast. Since the bike is being held steady, the additional lean/steer created is not being measured. We've seen this before - a position will test fast in a tunnel, but turn out to be slower in the real world once you're actually riding the bike. Now, you'd think I'd say, "See there, we proved the tunnel wrong." I'm not so sure. You see, it would be easy to give up on this position based on the results, and at the moment, there's nothing wrong with doing just that. However, I wonder what would happen if I gave myself time to adapt to this position? Would I become more comfortable? Should I perhaps add more reach to see if that helps? If, over time, I do adapt, would the drag numbers come down closer to what a tunnel would predict? Right now, I don't have that answer. Once we go to the tunnel, I think it would be fun to measure this position to see if it does test fast, and then give myself time to acclimate and measure throughout that adaptation period to see if drag is decreasing in the real world. I'll update when I complete the testing process.
Not all aero bars allow for independent adjustment of the extensions and pads, so you're forced to angle the entire base bar to achieve the desired forearm angle. This effectively hurts the bar aerodynamically as you've taken it's airfoil shape and angled it in a sub-optimal configuration creating more drag. But here's the funny thing...the testing we've conducted has shown that the gain from angling your arms is so great that we still see an aerodynamic advantage even with the negative effect of the bar. It's not as good as if the bar did allow for the independent adjustment, but it's still a net gain.
Below I've included results from a few others who've tested this position. There are many more, but these are noteworthy. You'll notice two of them involved tilting the entire aero bar as noted above. Each had a net gain. Rider #2 is interesting because of the huge gain - 22 watts. So hard to believe, we tested multiple times to confirm the results. Also interesting is that we lost much of that gain if we angled his extensions just a little more. There's a client or two who hasn't tested faster with their arms angled up, but they're the clear minority. If you are one of those clients, let me know and I'll post the numbers here with your permission. Your name will not be associated with the numbers, but it would be great to include them in the article because, nothing works for everyone.
|Rider||Watts Saved||Time Saved 180K (min)||Notes|
|#1||7.5||5.72||Entire 3T Brezza bar tilted|
|#2||22.1||8||Re-tested to confirm results|
|#3||6.9||3.6||Entire USE aero bar tilted|
If you're riding your current aero position with arms parallel to the ground or even (gasp!) with your wrists below your elbows, it's certainly worth a try to angle those arms up as long as your bike allows for it. Chances are, there's a nice benefit to both comfort and aerodynamic efficiency. If your bike doesn't allow for this type of adjustment, then shame on the manufacturer for designing their bike and/or aero bar with such a restraint. If you work for such a manufacturer, just know you're likely forcing your customers into a less-than-optimal position, and in the future you should probably allow for this type of adjustment in your aero bar. In my opinion, any athlete looking to purchase a new aero bike would be foolhardy to overlook such a restriction. After all, when you gain both comfort and speed from such a simple position change, it's not too much to ask for your bike to allow it.