So this weekend I basically did nothing but speed testing. I did every kind of speed testing I could think of, in fact.
On Friday I took my Roubaix out to my favorite test trail and did several four mile runs, comparing the effects of arm sleeves and my Eolus track helmet to no sleeves and my regular Specialized road helmet. At the speed I can currently hold for long periods ~22 mph, the difference was negligible. In comparing the power/speed data from various runs, I couldn't see the slightest benefit from arm sleeves and the super aero Eolus helmet. In a couple of runs, the speeds were identical and the power output differed by only 1 watt. Drag increases in proportion to the square of the volocity however, so physics dictates that at much higher speeds than I and vast majority of weekend riders can maintain, the benefits of making myself more aero would have to produce clear, measurable results, but I saw no practical benefit in conducting these sorts of tests at speeds that I can't maintain for any significant time.
On Saturday I went on a group ride, and discovered the one scenario in which my new Garmin video camera becomes a valuable tool for scientific testing. In fact, I can't think of any other way to conduct these types of tests that would produce results nearly as good. What I wanted to see was the effects of drafting, and for this, watching a video while the power/speed data is displayed in real time right on the screen is ideal. So with me in the lead, my average speed of 21-22 mph required ~200 watts, just as I'd noticed on many solo rides. With one rider in front of me, the same speed could be maintained with about 30 watts less power. With two or more riders ahead of me, the same speed could be maintained with 60-70 watts less. There is one section of the video where I deliberately changed my position relative to the lead rider to see if one position proved markedly better at saving watts; I couldn't find one.
Interestingly enough, I've done this sort of test before while riding my M5 recumbent, and noticed that in those cases the benefits of drafting someone on an upright were far greater. There have been times when I rode behind another rider at 21 mph, and noticed that I only had to put out 80 watts to match his speed. Unfortunately upright riders see little if any benefit from drafting a recumbent, so as a courtesy to the rest of the group, I try to stay out of the paceline whenever possible.
Today I took my Specialized Venge out to my favorite test trail and repeated the tests I'd conducted there on Friday with the Roubaix. I fully expected to see very different results. The Venge is clearly much more aero than the Roubaix, starting by placing the rider in a much more aggressive seating position, making the most of it's aero frame technology, and being equipped with a set of deep dish aero wheels. But once again, the test results were so close that nothing definitive could be concluded from them. The Venge did perform slightly better than the Roubaix on my four mile segment, but the difference was so small that just a tiny tailwind could account for it. In the end, the results were both amazing and disappointing. What it suggests is that for the average club rider, spending loads of money to make the bike more aerodynamically efficient is just pointless. I suspect that's because on an upright, the rider accounts for about 80% of the drag, so trying to squeeze significantly more speed out of the thing that's only responsible for 20% of the drag just isn't realistic. At least not at the speeds most riders are capable of.
