Geek Tech - Tribikes & Aerodynamics

Warning: This is gonna be techy and geeky as hell. You see, I'm really a geek at heart. Aside from doing math calculations during the run, I also enjoy playing Jeopardy, Trivial Pursuit and the like. I'm a Wiki whore, and often immerse myself not only in the history of things, but also in its science and art. Triathlon is no different.

I'm not at all an expert at these things. I am merely an enthusiast who loves the technical and scientific aspect of the sport - especially the bike. Let's start with Triathlon Bikes.

Aerobars does not a tri bike make. In the true sense, a triathlon bike is specifically designed to be ridden both comfortably and efficiently in the aero position (elbows on aerobar pads). Geometry is the main difference between a Road and Tri bike. The geometry of a Tri bike makes it easier to ride in the aero position. The main differences are the steeper seat tube angle (76-78 vs 73-74) and the shorter top tube, allowing the rider to be more 'forward'. Also, Tri bikes have shorter headtubes, allowing the rider to 'get lower' up front - for that more aerodynamic profile. Lastly, Tri-bikes tend to have a longer Front-Center (bottom bracket to front wheel axle), for better handling in the aero position.

Taken from Bikesport Michigan

Let's move to Aerodynamics. I'll avoid most of the technical mumbo-jumbo and try to site some real (triathlon) world dilemmas. On a flat road, drag makes up around 90% of the total rider's resistance. 80% of this drag is the rider, 20% being the bike. This means that practically speaking, aerodynamically superior bike equipment does not play as big a part as an aerodynamic position does. Simply put - an aerodynamic position will provide the most time savings. Of course, this assumes that the rider can comfortably stay in that position, generate a decent amount of power and safely steer the ship. The most aerodynamic position is useless if the rider is unable to either generate power in that position, or stay in that position. In these cases, some riders are better off riding a standard road bike, on the hoods.

Weight savings is another very popular topic when it comes to bikes. 'Lighter is better' seems to be the prevailing train of thought. Yes, in a world where I had a bottomless supply of cash, I would most probably build a barely UCI legal bike, with the most aerodynamic parts known to man, and the deepest wheels suitable to the bike course. But of course, that's not the case.

In a test Cervelo did, they pitted 2 bikes (22lb and 17lb) on the same 40km course with the same rider. They found out that the 17lb bike was ONLY 36 seconds faster over 40km. Pathetic, right?

That's the bike - what happened to the rider? Let's assume an 18lb bike, and a 160lb rider. Total weight = 178lb. This means that the bike is only 10% of the total equation. A 1lb saving on the bike, will only mean a .5% saving in overall weight. How much time will that 1lb saving get you over 40km? Around 4 seconds. Lose a pound yourself, and you've saved 4 seconds, and a couple of thousand bucks.

In a humorous, but very technically accurate article, Evan McFarlane explains how his relatively slimmer 'aerodynamic' ankles in fact, have twice the amount of time savings as a top of the line Cervelo P3 Tri Bike. Funny, but true.

So what really am I getting at? I guess what Lance Armstrong says is really right - 'It's not about the bike'. I say that every time I get passed by a 60 year old on a hybrid bike going up Antipolo, and every time I ogle at the uber bikes I cannot afford. Good thing I haven't gotten passed by that Selecta Tri Bike.